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Dr. Carleen Eaton

Dr. Carleen Eaton

The Immune System

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Table of Contents

Section 1: Chemistry of Life
Elements, Compounds, and Chemical Bonds

56m 18s

Intro
0:00
Elements
0:09
Elements
0:48
Matter
0:55
Naturally Occurring Elements
1:12
Atomic Number and Atomic Mass
2:39
Compounds
3:06
Molecule
3:07
Compounds
3:14
Examples
3:20
Atoms
4:53
Atoms
4:56
Protons, Neutrons, and Electrons
5:29
Isotopes
10:42
Energy Levels of Electrons
13:01
Electron Shells
13:13
Valence Shell
13:22
Example: Electron Shells and Potential Energy
13:28
Covalent Bonds
19:52
Covalent Bonds
19:54
Examples
20:03
Polar and Nonpolar Covalent Bonds
23:54
Polar Bond
24:07
Nonpolar Bonds
24:17
Examples
24:25
Ionic Bonds
29:04
Ionic Bond, Cations, Anions
29:19
Example: NaCl
29:30
Hydrogen Bond
33:18
Hydrogen Bond
33:20
Chemical Reactions
35:36
Example: Reactants, Products and Chemical Reactions
35:45
Molecular Mass and Molar Concentration
38:45
Avogadro's Number and Mol
39:12
Examples: Molecular Mass and Molarity
42:10
Example 1: Proton, Neutrons and Electrons
47:05
Example 2: Reactants and Products
49:35
Example 3: Bonding
52:39
Example 4: Mass
53:59
Properties of Water

50m 23s

Intro
0:00
Molecular Structure of Water
0:21
Molecular Structure of Water
0:27
Properties of Water
4:30
Cohesive
4:55
Transpiration
5:29
Adhesion
6:20
Surface Tension
7:17
Properties of Water, cont.
9:14
Specific Heat
9:25
High Heat Capacity
13:24
High Heat of Evaporation
16:42
Water as a Solvent
21:13
Solution
21:28
Solvent
21:48
Example: Water as a Solvent
22:22
Acids and Bases
25:40
Example
25:41
pH
36:30
pH Scale: Acidic, Neutral, and Basic
36:35
Example 1: Molecular Structure and Properties of Water
41:18
Example 2: Special Properties of Water
42:53
Example 3: pH Scale
44:46
Example 4: Acids and Bases
46:19
Organic Compounds

53m 54s

Intro
0:00
Organic Compounds
0:09
Organic Compounds
0:11
Inorganic Compounds
0:15
Examples: Organic Compounds
1:15
Isomers
5:52
Isomers
5:55
Structural Isomers
6:23
Geometric Isomers
8:14
Enantiomers
9:55
Functional Groups
12:46
Examples: Functional Groups
12:59
Amino Group
13:51
Carboxyl Group
14:38
Hydroxyl Group
15:22
Methyl Group
16:14
Carbonyl Group
16:30
Phosphate Group
17:51
Carbohydrates
18:26
Carbohydrates
19:07
Example: Monosaccharides
21:12
Carbohydrates, cont.
24:11
Disaccharides, Polysaccharides and Examples
24:21
Lipids
35:52
Examples of Lipids
36:04
Saturated and Unsaturated
38:57
Phospholipids
43:26
Phospholipids
43:29
Example
43:34
Steroids
46:24
Cholesterol
46:28
Example 1: Isomers
48:11
Example 2: Functional Groups
50:45
Example 3: Galactose, Ketose, and Aldehyde Sugar
52:24
Example 4: Class of Molecules
53:06
Nucleic Acids and Proteins

37m 23s

Intro
0:00
Nucleic Acids
0:09
Deoxyribonucleic Acid (DNA) and Ribonucleic Acid (RNA)
0:29
Nucleic Acids, cont.
2:56
Purines
3:10
Pyrimidines
3:32
Double Helix
4:59
Double Helix and Example
5:01
Proteins
12:33
Amino Acids and Polypeptides
12:39
Examples: Amino Acid
13:25
Polypeptide Formation
18:09
Peptide Bonds
18:14
Primary Structure
18:35
Protein Structure
23:19
Secondary Structure
23:22
Alpha Helices and Beta Pleated Sheets
23:34
Protein Structure
25:43
Tertiary Structure
25:44
5 Types of Interaction
26:56
Example 1: Complementary DNA Strand
31:45
Example 2: Differences Between DNA and RNA
33:19
Example 3: Amino Acids
34:32
Example 4: Tertiary Structure of Protein
35:46
Section 2: Cell Structure and Function
Cell Types (Prokaryotic and Eukaryotic)

45m 50s

Intro
0:00
Cell Theory and Cell Types
0:12
Cell Theory
0:13
Prokaryotic and Eukaryotic Cells
0:36
Endosymbiotic Theory
1:13
Study of Cells
4:07
Tools and Techniques
4:08
Light Microscopes
5:08
Light vs. Electron Microscopes: Magnification
5:18
Light vs. Electron Microscopes: Resolution
6:26
Light vs. Electron Microscopes: Specimens
7:53
Electron Microscopes: Transmission and Scanning
8:28
Cell Fractionation
10:01
Cell Fractionation Step 1: Homogenization
10:33
Cell Fractionation Step 2: Spin
11:24
Cell Fractionation Step 3: Differential Centrifugation
11:53
Comparison of Prokaryotic and Eukaryotic Cells
14:12
Prokaryotic vs. Eukaryotic Cells: Domains
14:43
Prokaryotic vs. Eukaryotic Cells: Plasma Membrane
15:40
Prokaryotic vs. Eukaryotic Cells: Cell Walls
16:15
Prokaryotic vs. Eukaryotic Cells: Genetic Materials
16:38
Prokaryotic vs. Eukaryotic Cells: Structures
17:28
Prokaryotic vs. Eukaryotic Cells: Unicellular and Multicellular
18:19
Prokaryotic vs. Eukaryotic Cells: Size
18:31
Plasmids
18:52
Prokaryotic vs. Eukaryotic Cells
19:22
Nucleus
19:24
Organelles
19:48
Cytoskeleton
20:02
Cell Wall
20:35
Ribosomes
20:57
Size
21:37
Comparison of Plant and Animal Cells
22:15
Plasma Membrane
22:55
Plant Cells Only: Cell Walls
23:12
Plant Cells Only: Central Vacuole
25:08
Animal Cells Only: Centrioles
26:40
Animal Cells Only: Lysosomes
27:43
Plant vs. Animal Cells
29:16
Overview of Plant and Animal Cells
29:17
Evidence for the Endosymbiotic Theory
30:52
Characteristics of Mitochondria and Chloroplasts
30:54
Example 1: Prokaryotic vs. Eukaryotic Cells
35:44
Example 2: Endosymbiotic Theory and Evidence
38:38
Example 3: Plant and Animal Cells
41:49
Example 4: Cell Fractionation
43:44
Subcellular Structure

59m 38s

Intro
0:00
Prokaryotic Cells
0:09
Shapes of Prokaryotic Cells
0:22
Cell Wall
1:19
Capsule
3:23
Pili/Fimbria
3:54
Flagella
4:35
Nucleoid
6:16
Plasmid
6:37
Ribosomes
7:09
Eukaryotic Cells (Animal Cell Structure)
8:01
Plasma Membrane
8:13
Microvilli
8:48
Nucleus
9:47
Nucleolus
11:06
Ribosomes: Free and Bound
12:26
Rough Endoplasmic Reticulum (RER)
13:43
Eukaryotic Cells (Animal Cell Structure), cont.
14:51
Endoplasmic Reticulum: Smooth and Rough
15:08
Golgi Apparatus
17:55
Vacuole
20:43
Lysosome
22:01
Mitochondria
25:40
Peroxisomes
28:18
Cytoskeleton
30:41
Cytoplasm and Cytosol
30:53
Microtubules: Centrioles, Spindel Fibers, Clagell, Cillia
32:06
Microfilaments
36:39
Intermediate Filaments and Kerotin
38:52
Eukaryotic Cells (Plant Cell Structure)
40:08
Plasma Membrane, Primary Cell Wall, and Secondary Cell Wall
40:30
Middle Lamella
43:21
Central Cauole
44:12
Plastids: Leucoplasts, Chromoplasts, Chrloroplasts
45:35
Chloroplasts
47:06
Example 1: Structures and Functions
48:46
Example 2: Cell Walls
51:19
Example 3: Cytoskeleton
52:53
Example 4: Antibiotics and the Endosymbiosis Theory
56:55
Cell Membranes and Transport

53m 10s

Intro
0:00
Cell Membrane Structure
0:09
Phospholipids Bilayer
0:11
Chemical Structure: Amphipathic and Fatty Acids
0:25
Cell Membrane Proteins
2:44
Fluid Mosaic Model
2:45
Peripheral Proteins and Integral Proteins
3:19
Transmembrane Proteins
4:34
Cholesterol
4:48
Functions of Membrane Proteins
6:39
Transport Across Cell Membranes
9:52
Transport Across Cell Membranes
9:53
Methods of Passive Transport
12:07
Passive and Active Transport
12:08
Simple Diffusion
12:45
Facilitated Diffusion
15:20
Osmosis
17:17
Definition and Example of Osmosis
17:18
Hypertonic, Hypotonic, and Isotonic
21:47
Active Transport
27:57
Active Transport
28:17
Sodium and Potassium Pump
29:45
Cotransport
34:38
2 Types of Active Transport
37:09
Endocytosis and Exocytosis
37:38
Endocytosis and Exocytosis
37:51
Types of Endocytosis: Pinocytosis
40:39
Types of Endocytosis: Phagocytosis
41:02
Receptor Mediated Endocytosis
41:27
Receptor Mediated Endocytosis
41:28
Example 1: Cell Membrane and Permeable Substances
43:59
Example 2: Osmosis
45:20
Example 3: Active Transport, Cotransport, Simple and Facilitated Diffusion
47:36
Example 4: Match Terms with Definition
50:55
Cellular Communication

57m 9s

Intro
0:00
Extracellular Matrix
0:28
The Extracellular Matrix (ECM)
0:29
ECM in Animal Cells
0:55
Fibronectin and Integrins
1:34
Intercellular Communication in Plants
2:48
Intercellular Communication in Plants: Plasmodesmata
2:50
Cell to Cell Communication in Animal Cells
3:39
Cell Junctions
3:42
Desmosomes
3:54
Tight Junctions
5:07
Gap Junctions
7:00
Cell Signaling
8:17
Cell Signaling: Ligand and Signal Transduction Pathway
8:18
Direct Contact
8:48
Over Distances Contact and Hormones
10:09
Stages of Cell Signaling
11:53
Reception Phase
11:54
Transduction Phase
13:49
Response Phase
14:45
Cell Membrane Receptors
15:37
G-Protein Coupled Receptor
15:38
Cell Membrane Receptor, Cont.
21:37
Receptor Tyrosine Kinases (RTKs)
21:38
Autophosphorylation, Monomer, and Dimer
22:57
Cell Membrane Receptor, Cont.
27:01
Ligand-Gated Ion Channels
27:02
Intracellular Receptors
29:43
Intracellular Receptor and Receptor -Ligand Complex
29:44
Signal Transduction
32:57
Signal Transduction Pathways
32:58
Adenylyl Cyclase and cAMP
35:53
Second Messengers
39:18
cGMP, Inositol Trisphosphate, and Diacylglycerol
39:20
Cell Response
45:15
Cell Response
45:16
Apoptosis
46:57
Example 1: Tight Junction and Gap Junction
48:29
Example 2: Three Phases of Cell Signaling
51:48
Example 3: Ligands and Binding of Hormone
54:03
Example 4: Signal Transduction
56:06
Section 3: Cell Division
The Cell Cycle

37m 49s

Intro
0:00
Functions of Cell Division
0:09
Overview of Cell Division: Reproduction, Growth, and Repair
0:11
Important Term: Daughter Cells
2:25
Chromosome Structure
3:36
Chromosome Structure: Sister Chromatids and Centromere
3:37
Chromosome Structure: Chromatin
4:31
Chromosome with One Chromatid or Two Chromatids
5:25
Chromosome Structure: Long and Short Arm
6:49
Mitosis and Meiosis
7:00
Mitosis
7:41
Meiosis
8:40
The Cell Cycle
10:43
Mitotic Phase and Interphase
10:44
Cytokinesis
15:51
Cytokinesis in Animal Cell: Cleavage Furrow
15:52
Cytokinesis in Plant Cell: Cell Plate
17:28
Control of the Cell Cycle
18:28
Cell Cycle Control System and Checkpoints
18:29
Cyclins and Cyclin Dependent Kinases
21:18
Cyclins and Cyclin Dependent Kinases (CDKSs)
21:20
MPF
23:17
Internal Factor Regulating Cell Cycle
24:00
External Factor Regulating Cell Cycle
24:53
Contact Inhibition and Anchorage Dependent
25:53
Cancer and the Cell Cycle
27:42
Cancer Cells
27:46
Example1: Parts of the Chromosome
30:15
Example 2: Cell Cycle
31:50
Example 3: Control of the Cell Cycle
33:32
Example 4: Cancer and the Cell
35:01
Mitosis

35m 1s

Intro
0:00
Review of the Cell Cycle
0:09
Interphase: G1 Phase
0:34
Interphase: S Phase
0:56
Interphase: G2 Phase
1:31
M Phase: Mitosis and Cytokinesis
1:47
Overview of Mitosis
3:08
What is Mitosis?
3:10
Overview of Mitosis
3:17
Diploid and Haploid
5:37
Homologous Chromosomes
6:04
The Spindle Apparatus
11:57
The Spindle Apparatus
12:00
Centrosomes and Centrioles
12:40
Microtubule Organizing Center
13:03
Spindle Fiber of Spindle Microtubules
13:23
Kinetochores
14:06
Asters
15:45
Prophase
16:47
First Phase of Mitosis: Prophase
16:54
Metaphase
20:05
Second Phase of Mitosis: Metaphase
20:10
Anaphase
22:52
Third Phase of Mitosis: Anaphase
22:53
Telophase and Cytokinesis
24:34
Last Phase of Mitosis: Telophase and Cytokinesis
24:35
Summary of Mitosis
27:46
Summary of Mitosis
27:47
Example 1: Spindle Apparatus
28:50
Example 2: Last Phase of Mitosis
30:39
Example 3: Prophase
32:41
Example 4: Identify the Phase
33:52
Meiosis

1h 58s

Intro
0:00
Haploid and Diploid Cells
0:09
Diploid and Somatic Cells
0:29
Haploid and Gametes
1:20
Example: Human Cells and Chromosomes
1:41
Sex Chromosomes
6:00
Comparison of Mitosis and Meiosis
10:42
Mitosis Vs. Meiosis: Cell Division
10:59
Mitosis Vs. Meiosis: Daughter Cells
12:31
Meiosis: Pairing of Homologous Chromosomes
13:40
Mitosis and Meiosis
14:21
Process of Mitosis
14:27
Process of Meiosis
16:12
Synapsis and Crossing Over
19:14
Prophase I: Synapsis and Crossing Over
19:15
Chiasmata
22:33
Meiosis I
25:49
Prophase I: Crossing Over
25:50
Metaphase I: Homologs Line Up
26:00
Anaphase I: Homologs Separate
28:16
Telophase I and Cytokinesis
29:15
Independent Assortment
30:58
Meiosis II
32:17
Propphase II
33:50
Metaphase II
34:06
Anaphase II
34:50
Telophase II
36:09
Cytokinesis
37:00
Summary of Meiosis
38:15
Summary of Meiosis
38:16
Cell Division Mechanism in Plants
41:57
Example 1: Cell Division and Meiosis
46:15
Example 2: Phases of Meiosis
50:22
Example 3: Label the Figure
54:29
Example 4: Four Differences Between Mitosis and Meiosis
56:37
Section 4: Cellular Energetics
Enzymes

51m 3s

Intro
0:00
Law of Thermodynamics
0:08
Thermodynamics
0:09
The First Law of Thermodynamics
0:37
The Second Law of Thermodynamics
1:24
Entropy
1:35
The Gibbs Free Energy Equation
3:07
The Gibbs Free Energy Equation
3:08
ATP
8:23
Adenosine Triphosphate (ATP)
8:24
Cellular Respiration
11:32
Catabolic Pathways
12:28
Anabolic Pathways
12:54
Enzymes
14:31
Enzymes
14:32
Enzymes and Exergonic Reaction
14:40
Enzymes and Endergonic Reaction
16:36
Enzyme Specificity
21:29
Substrate
21:41
Induced Fit
23:04
Factors Affecting Enzyme Activity
25:55
Substrate Concentration
26:07
pH
27:10
Temperature
29:14
Presence of Cofactors
29:57
Regulation of Enzyme Activity
31:12
Competitive Inhibitors
32:13
Noncompetitive Inhibitors
33:52
Feedback Inhibition
35:22
Allosteric Interactions
36:56
Allosteric Regulators
37:00
Example 1: Is the Inhibitor Competitive or Noncompetitive?
40:49
Example 2: Thermophiles
44:18
Example 3: Exergonic or Endergonic
46:09
Example 4: Energy Vs. Reaction Progress Graph
48:47
Glycolysis and Anaerobic Respiration

38m 1s

Intro
0:00
Cellular Respiration Overview
0:13
Cellular Respiration
0:14
Anaerobic Respiration vs. Aerobic Respiration
3:50
Glycolysis Overview
4:48
Overview of Glycolysis
4:50
Glycolysis Involves a Redox Reaction
7:02
Redox Reaction
7:04
Glycolysis
15:04
Important Facts About Glycolysis
15:07
Energy Invested Phase
16:12
Splitting of Fructose 1,6-Phosphate and Energy Payoff Phase
17:50
Substrate Level Phophorylation
22:12
Aerobic Versus Anaerobic Respiration
23:57
Aerobic Versus Anaerobic Respiration
23:58
Cellular Respiration Overview
27:15
When Cellular Respiration is Anaerobic
27:17
Glycolysis
28:26
Alcohol Fermentation
28:45
Lactic Acid Fermentation
29:58
Example 1: Glycolysis
31:04
Example 2: Glycolysis, Fermentation and Anaerobic Respiration
33:44
Example 3: Aerobic Respiration Vs. Anaerobic Respiration
35:25
Example 4: Exergonic Reaction and Endergonic Reaction
36:42
Aerobic Respiration

51m 6s

Intro
0:00
Aerobic Vs. Anaerobic Respiration
0:06
Aerobic and Anaerobic Comparison
0:07
Review of Glycolysis
1:48
Overview of Glycolysis
2:06
Glycolysis: Energy Investment Phase
2:25
Glycolysis: Energy Payoff Phase
2:58
Conversion of Pyruvate to Acetyl CoA
4:55
Conversion of Pyruvate to Acetyl CoA
4:56
Energy Formation
8:06
Mitochondrial Structure
8:58
Endosymbiosis Theory
9:23
Matrix
10:00
Outer Membrane, Inner Membrane, and Intermembrane Space
10:43
Cristae
11:47
The Citric Acid Cycle
12:11
The Citric Acid Cycle (Also Called Krebs Cycle)
12:12
Substrate Level Phosphorylation
18:47
Summary of ATP, NADH, and FADH2 Production
23:13
Process: Glycolysis
23:28
Process: Acetyl CoA Production
23:36
Process: Citric Acid Cycle
23:52
The Electron Transport Chain
24:24
Oxidative Phosphorylation
24:28
The Electron Transport Chain and ATP Synthase
25:20
Carrier Molecules: Cytochromes
27:18
Carrier Molecules: Flavin Mononucleotide (FMN)
28:05
Chemiosmosis
32:46
The Process of Chemiosmosis
32:47
Summary of ATP Produced by Aerobic Respiration
38:24
ATP Produced by Aerobic Respiration
38:27
Example 1: Aerobic Respiration
43:38
Example 2: Label the Location for Each Process and Structure
45:08
Example 3: The Electron Transport Chain
47:06
Example 4: Mitochondrial Inner Membrane
48:38
Photosynthesis

1h 2m 52s

Intro
0:00
Photosynthesis
0:09
Introduction to Photosynthesis
0:10
Autotrophs and Heterotrophs
0:25
Overview of Photosynthesis Reaction
1:05
Leaf Anatomy and Chloroplast Structure
2:54
Chloroplast
2:55
Cuticle
3:16
Upper Epidermis
3:27
Mesophyll
3:40
Stomates
4:00
Guard Cells
4:45
Transpiration
5:01
Vascular Bundle
5:20
Stroma and Double Membrane
6:20
Grana
7:17
Thylakoids
7:30
Dark Reaction and Light Reaction
7:46
Light Reactions
8:43
Light Reactions
8:47
Pigments: Chlorophyll a, Chlorophyll b, and Carotenoids
9:19
Wave and Particle
12:10
Photon
12:34
Photosystems
13:24
Photosystems
13:28
Reaction-Center Complex and Light Harvesting Complexes
14:01
Noncyclic Photophosphorylation
17:46
Noncyclic Photophosphorylation Overview
17:47
What is Photophosphorylation?
18:25
Noncyclic Photophosphorylation Process
19:07
Photolysis and The Rest of Noncyclic Photophosphorylation
21:33
Cyclic Photophosphorylation
31:45
Cyclic Photophosphorylation
31:46
Light Independent Reactions
34:34
The Calvin Cycle
34:35
C3 Plants and Photorespiration
40:31
C3 Plants and Photorespiration
40:32
C4 Plants
45:32
C4 Plants: Structures and Functions
45:33
CAM Plants
50:25
CAM Plants: Structures and Functions
50:35
Example 1: Calvin Cycle
54:34
Example 2: C4 Plant
55:48
Example 3: Photosynthesis and Photorespiration
58:35
Example 4: CAM Plants
1:00:41
Section 5: Molecular Genetics
DNA Synthesis

38m 45s

Intro
0:00
Review of DNA Structure
0:09
DNA Molecules
0:10
Nitrogenous Base: Pyrimidines and Purines
1:25
DNA Double Helix
3:03
Complementary Strands of DNA
3:12
5' to 3' & Antiparallel
4:55
Overview of DNA Replication
7:10
DNA Replication & Semiconservative
7:11
DNA Replication
10:26
Origin of Replication
10:28
Helicase
11:10
Single-Strand Binding Protein
12:05
Topoisomerases
13:14
DNA Polymerase
14:26
Primase
15:55
Leading and Lagging Strands
16:51
Leading Strand and Lagging Strand
16:52
Okazaki Fragments
18:10
DNA Polymerase I
20:11
Ligase
21:12
Proofreading and Mismatch Repair
22:18
Proofreading
22:19
Mismatch
23:33
Telomeres
24:58
Telomeres
24:59
Example 1: Function of Enzymes During DNA Synthesis
28:09
Example 2: Accuracy of the DNA Sequence
31:42
Example 3: Leading Strand and Lagging Strand
32:38
Example 4: Telomeres
35:40
Transcription and Translation

1h 17m 1s

Intro
0:00
Transcription and Translation Overview
0:07
From DNA to RNA to Protein
0:09
Structure and Types of RNA
3:14
Structure and Types of RNA
3:33
mRNA
6:19
rRNA
7:02
tRNA
7:28
Transcription
7:54
Initiation Phase
8:11
Elongation Phase
12:12
Termination Phase
14:51
RNA Processing
16:11
Types of RNA Processing
16:12
Exons and Introns
16:35
Splicing & Spliceosomes
18:27
Addition of a 5' Cap and a Poly A tail
20:41
Alternative Splicing
21:43
Translation
23:41
Nucleotide Triplets or Codons
23:42
Start Codon
25:24
Stop Codons
25:38
Coding of Amino Acids and Wobble Position
25:57
Translation Cont.
28:29
Transfer RNA (tRNA): Structures and Functions
28:30
Ribosomes
35:15
Peptidyl, Aminoacyl, and Exit Site
35:23
Steps of Translation
36:58
Initiation Phase
37:12
Elongation Phase
43:12
Termination Phase
45:28
Mutations
49:43
Types of Mutations
49:44
Substitutions: Silent
51:11
Substitutions: Missense
55:27
Substitutions: Nonsense
59:37
Insertions and Deletions
1:01:10
Example 1: Three Types of Processing that are Performed on pre-mRNA
1:06:53
Example 2: The Process of Translation
1:09:10
Example 3: Transcription
1:12:04
Example 4: Three Types of Substitution Mutations
1:14:09
Viral Structure and Genetics

43m 12s

Intro
0:00
Structure of Viruses
0:09
Structure of Viruses: Capsid and Envelope
0:10
Bacteriophage
1:48
Other Viruses
2:28
Overview of Viral Reproduction
3:15
Host Range
3:48
Step 1: Bind to Host Cell
4:39
Step 2: Viral Nuclei Acids Enter the Cell
5:15
Step 3: Viral Nucleic Acids & Proteins are Synthesized
5:54
Step 4: Virus Assembles
6:34
Step 5: Virus Exits the Cell
6:55
The Lytic Cycle
7:37
Steps in the Lytic Cycle
7:38
The Lysogenic Cycle
11:27
Temperate Phage
11:34
Steps in the Lysogenic Cycle
12:09
RNA Viruses
16:57
Types of RNA Viruses
17:15
Positive Sense
18:16
Negative Sense
18:48
Reproductive Cycle of RNA Viruses
19:32
Retroviruses
25:48
Complementary DNA (cDNA) & Reverse Transcriptase
25:49
Life Cycle of a Retrovirus
28:22
Prions
32:42
Prions: Definition and Examples
32:45
Viroids
34:46
Example 1: The Lytic Cycle
35:37
Example 2: Retrovirus
38:03
Example 3: Positive Sense RNA vs. Negative Sense RNA
39:10
Example 4: The Lysogenic Cycle
40:42
Bacterial Genetics and Gene Regulation

49m 45s

Intro
0:00
Bacterial Genomes
0:09
Structure of Bacterial Genomes
0:16
Transformation
1:22
Transformation
1:23
Vector
2:49
Transduction
3:32
Process of Transduction
3:38
Conjugation
8:06
Conjugation & F factor
8:07
Operons
14:02
Definition and Example of Operon
14:52
Structural Genes
16:23
Promoter Region
17:04
Regulatory Protein & Operators
17:53
The lac Operon
20:09
The lac Operon: Inducible System
20:10
The trp Operon
28:02
The trp Operon: Repressible System
28:03
Corepressor
31:37
Anabolic & Catabolic
33:12
Positive Regulation of the lac Operon
34:39
Positive Regulation of the lac Operon
34:40
Example 1: The Process of Transformation
39:07
Example 2: Operon & Terms
43:29
Example 3: Inducible lac Operon and Repressible trp Operon
45:15
Example 4: lac Operon
47:10
Eukaryotic Gene Regulation and Mobile Genetic Elements

54m 26s

Intro
0:00
Mechanism of Gene Regulation
0:11
Differential Gene Expression
0:13
Levels of Regulation
2:24
Chromatin Structure and Modification
4:35
Chromatin Structure
4:36
Levels of Packing
5:50
Euchromatin and Heterochromatin
8:58
Modification of Chromatin Structure
9:58
Epigenetic
12:49
Regulation of Transcription
14:20
Promoter Region, Exon, and Intron
14:26
Enhancers: Control Element
15:31
Enhancer & DNA-Bending Protein
17:25
Coordinate Control
21:23
Silencers
23:01
Post-Transcriptional Regulation
24:05
Post-Transcriptional Regulation
24:07
Alternative Splicing
27:19
Differences in mRNA Stability
28:02
Non-Coding RNA Molecules: micro RNA & siRNA
30:01
Regulation of Translation and Post-Translational Modifications
32:31
Regulation of Translation and Post-Translational Modifications
32:55
Ubiquitin
35:21
Proteosomes
36:04
Transposons
37:50
Mobile Genetic Elements
37:56
Barbara McClintock
38:37
Transposons & Retrotransposons
40:38
Insertion Sequences
43:14
Complex Transposons
43:58
Example 1: Four Mechanisms that Decrease Production of Protein
45:13
Example 2: Enhancers and Gene Expression
49:09
Example 3: Primary Transcript
50:41
Example 4: Retroviruses and Retrotransposons
52:11
Biotechnology

49m 26s

Intro
0:00
Definition of Biotechnology
0:08
Biotechnology
0:09
Genetic Engineering
1:05
Example: Golden Corn
1:57
Recombinant DNA
2:41
Recombinant DNA
2:42
Transformation
3:24
Transduction
4:24
Restriction Enzymes, Restriction Sites, & DNA Ligase
5:32
Gene Cloning
13:48
Plasmids
14:20
Gene Cloning: Step 1
17:35
Gene Cloning: Step 2
17:57
Gene Cloning: Step 3
18:53
Gene Cloning: Step 4
19:46
Gel Electrophoresis
27:25
What is Gel Electrophoresis?
27:26
Gel Electrophoresis: Step 1
28:13
Gel Electrophoresis: Step 2
28:24
Gel Electrophoresis: Step 3 & 4
28:39
Gel Electrophoresis: Step 5
29:55
Southern Blotting
31:25
Polymerase Chain Reaction (PCR)
32:11
Polymerase Chain Reaction (PCR)
32:12
Denaturing Phase
35:40
Annealing Phase
36:07
Elongation/ Extension Phase
37:06
DNA Sequencing and the Human Genome Project
39:19
DNA Sequencing and the Human Genome Project
39:20
Example 1: Gene Cloning
40:40
Example 2: Recombinant DNA
43:04
Example 3: Match Terms With Descriptions
45:43
Example 4: Polymerase Chain Reaction
47:36
Section 6: Heredity
Mendelian Genetics

1h 32m 8s

Intro
0:00
Background
0:40
Gregory Mendel & Mendel's Law
0:41
Blending Hypothesis
1:04
Particulate Inheritance
2:08
Terminology
2:55
Gene
3:05
Locus
3:57
Allele
4:37
Dominant Allele
5:48
Recessive Allele
7:38
Genotype
9:22
Phenotype
10:01
Homozygous
10:44
Heterozygous
11:39
Penetrance
11:57
Expressivity
14:15
Mendel's Experiments
15:31
Mendel's Experiments: Pea Plants
15:32
The Law of Segregation
21:16
Mendel's Conclusions
21:17
The Law of Segregation
22:57
Punnett Squares
28:27
Using Punnet Squares
28:30
The Law of Independent Assortment
32:35
Monohybrid
32:38
Dihybrid
33:29
The Law of Independent Assortment
34:00
The Law of Independent Assortment, cont.
38:13
The Law of Independent Assortment: Punnet Squares
38:29
Meiosis and Mendel's Laws
43:38
Meiosis and Mendel's Laws
43:39
Test Crosses
49:07
Test Crosses Example
49:08
Probability: Multiplication Rule and the Addition Rule
53:39
Probability Overview
53:40
Independent Events & Multiplication Rule
55:40
Mutually Exclusive Events & Addition Rule
1:00:25
Incomplete Dominance, Codominance and Multiple Alleles
1:02:55
Incomplete Dominance
1:02:56
Incomplete Dominance, Codominance and Multiple Alleles
1:07:06
Codominance and Multiple Alleles
1:07:08
Polygenic Inheritance and Pleoitropy
1:10:19
Polygenic Inheritance and Pleoitropy
1:10:26
Epistasis
1:12:51
Example of Epistasis
1:12:52
Example 1: Genetic of Eye Color and Height
1:17:39
Example 2: Blood Type
1:21:57
Example 3: Pea Plants
1:25:09
Example 4: Coat Color
1:28:34
Linked Genes and Non-Mendelian Modes of Inheritance

39m 38s

Intro
0:00
Review of the Law of Independent Assortment
0:14
Review of the Law of Independent Assortment
0:24
Linked Genes
6:06
Linked Genes
6:07
Bateson & Pannett: Pea Plants
8:00
Crossing Over and Recombination
15:17
Crossing Over and Recombination
15:18
Extranuclear Genes
20:50
Extranuclear Genes
20:51
Cytoplasmic Genes
21:31
Genomic Imprinting
23:45
Genomic Imprinting
23:58
Methylation
24:43
Example 1: Recombination Frequencies & Linkage Map
27:07
Example 2: Linked Genes
28:39
Example 3: Match Terms to Correct Descriptions
36:46
Example 4: Leber's Optic Neuropathy
38:40
Sex-Linked Traits and Pedigree Analysis

43m 39s

Intro
0:00
Sex-Linked Traits
0:09
Human Chromosomes, XY, and XX
0:10
Thomas Morgan's Drosophila
1:44
X-Inactivation and Barr Bodies
14:48
X-Inactivation Overview
14:49
Calico Cats Example
17:04
Pedigrees
19:24
Definition and Example of Pedigree
19:25
Autosomal Dominant Inheritance
20:51
Example: Huntington's Disease
20:52
Autosomal Recessive Inheritance
23:04
Example: Cystic Fibrosis, Tay-Sachs Disease, and Phenylketonuria
23:05
X-Linked Recessive Inheritance
27:06
Example: Hemophilia, Duchene Muscular Dystrohpy, and Color Blindess
27:07
Example 1: Colorblind
29:48
Example 2: Pedigree
37:07
Example 3: Inheritance Pattern
39:54
Example 4: X-inactivation
41:17
Section 7: Evolution
Natural Selection

1h 3m 28s

Intro
0:00
Background
0:09
Work of Other Scientists
0:15
Aristotle
0:43
Carl Linnaeus
1:32
George Cuvier
2:47
James Hutton
4:10
Thomas Malthus
5:05
Jean-Baptiste Lamark
5:45
Darwin's Theory of Natural Selection
7:50
Evolution
8:00
Natural Selection
8:43
Charles Darwin & The Galapagos Islands
10:20
Genetic Variation
20:37
Mutations
20:38
Independent Assortment
21:04
Crossing Over
24:40
Random Fertilization
25:26
Natural Selection and the Peppered Moth
26:37
Natural Selection and the Peppered Moth
26:38
Types of Natural Selection
29:52
Directional Selection
29:55
Stabilizing Selection
32:43
Disruptive Selection
34:21
Sexual Selection
36:18
Sexual Dimorphism
37:30
Intersexual Selection
37:57
Intrasexual Selection
39:20
Evidence for Evolution
40:55
Paleontology: Fossil Record
41:30
Biogeography
45:35
Continental Drift
46:06
Pangaea
46:28
Marsupials
47:11
Homologous and Analogous Structure
50:10
Homologous Structure
50:12
Analogous Structure
53:21
Example 1: Genetic Variation & Natural Selection
56:15
Example 2: Types of Natural Selection
58:07
Example 3: Mechanisms By Which Genetic Variation is Maintained Within a Population
1:00:12
Example 4: Difference Between Homologous and Analogous Structures
1:01:28
Population Genetic and Evolution

53m 22s

Intro
0:00
Review of Natural Selection
0:12
Review of Natural Selection
0:13
Genetic Drift and Gene Flow
4:40
Definition of Genetic Drift
4:41
Example of Genetic Drift: Cholera Epidemic
5:15
Genetic Drift: Founder Effect
7:28
Genetic Drift: Bottleneck Effect
10:27
Gene Flow
13:00
Quantifying Genetic Variation
14:32
Average Heterozygosity
15:08
Nucleotide Variation
17:05
Maintaining Genetic Variation
18:12
Heterozygote Advantage
19:45
Example of Heterozygote Advantage: Sickle Cell Anemia
20:21
Diploidy
23:44
Geographic Variation
26:54
Frequency Dependent Selection and Outbreeding
28:15
Neutral Traits
30:55
The Hardy-Weinberg Equilibrium
31:11
The Hardy-Weinberg Equilibrium
31:49
The Hardy-Weinberg Conditions
32:42
The Hardy-Weinberg Equation
34:05
The Hardy-Weinberg Example
36:33
Example 1: Match Terms to Descriptions
42:28
Example 2: The Hardy-Weinberg Equilibrium
44:31
Example 3: The Hardy-Weinberg Equilibrium
49:10
Example 4: Maintaining Genetic Variation
51:30
Speciation and Patterns of Evolution

51m 2s

Intro
0:00
Early Life on Earth
0:08
Early Earth
0:09
1920's Oparin & Haldane
0:58
Abiogenesis
2:15
1950's Miller & Urey
2:45
Ribozymes
5:34
3.5 Billion Years Ago
6:39
2.5 Billion Years Ago
7:14
1.5 Billion Years Ago
7:41
Endosymbiosis
8:00
540 Million Years Ago: Cambrian Explosion
9:57
Gradualism and Punctuated Equilibrium
11:46
Gradualism
11:47
Punctuated Equilibrium
12:45
Adaptive Radiation
15:08
Adaptive Radiation
15:09
Example of Adaptive Radiation: Galapogos Islands
17:11
Convergent Evolution, Divergent Evolution, and Coevolution
18:30
Convergent Evolution
18:39
Divergent Evolution
21:30
Coevolution
23:49
Speciation
26:27
Definition and Example of Species
26:29
Reproductive Isolation: Prezygotive
27:49
Reproductive Isolation: Post zygotic
29:28
Allopatric Speciation
30:21
Allopatric Speciation & Geographic Isolation
30:28
Genetic Drift
31:31
Sympatric Speciation
34:10
Sympatric Speciation
34:11
Polyploidy & Autopolyploidy
35:12
Habitat Isolation
39:17
Temporal Isolation
41:27
Selection Selection
41:40
Example 1: Pattern of Evolution
42:53
Example 2: Sympatric Speciation
45:16
Example 3: Patterns of Evolution
48:08
Example 4: Patterns of Evolution
49:27
Section 8: Diversity of Life
Classification

1h 51s

Intro
0:00
Systems of Classification
0:07
Taxonomy
0:08
Phylogeny
1:04
Phylogenetics Tree
1:44
Cladistics
3:37
Classification of Organisms
5:31
Example of Carl Linnaeus System
5:32
Domains
9:26
Kingdoms: Monera, Protista, Plantae, Fungi, Animalia
9:27
Monera
10:06
Phylogentics Tree: Eurkarya, Bacteria, Archaea
11:58
Domain Eukarya
12:50
Domain Bacteria
15:43
Domain Bacteria
15:46
Pathogens
16:41
Decomposers
18:00
Domain Archaea
19:43
Extremophiles Archaea: Thermophiles and Halophiles
19:44
Methanogens
20:58
Phototrophs, Autotrophs, Chemotrophs and Heterotrophs
24:40
Phototrophs and Chemotrophs
25:02
Autotrophs and Heterotrophs
26:54
Photoautotrophs
28:50
Photoheterotrophs
29:28
Chemoautotrophs
30:06
Chemoheterotrophs
31:37
Domain Eukarya
32:40
Domain Eukarya
32:43
Plant Kingdom
34:28
Protists
35:48
Fungi Kingdom
37:06
Animal Kingdom
38:35
Body Symmetry
39:25
Lack Symetry
39:40
Radial Symmetry: Sea Aneome
40:15
Bilateral Symmetry
41:55
Cephalization
43:29
Germ Layers
44:54
Diploblastic Animals
45:18
Triploblastic Animals
45:25
Ectoderm
45:36
Endoderm
46:07
Mesoderm
46:41
Coelomates
47:14
Coelom
47:15
Acoelomate
48:22
Pseudocoelomate
48:59
Coelomate
49:31
Protosomes
50:46
Deuterosomes
51:20
Example 1: Domains
53:01
Example 2: Match Terms with Descriptions
56:00
Example 3: Kingdom Monera and Domain Archaea
57:50
Example 4: System of Classification
59:37
Bacteria

36m 46s

Intro
0:00
Comparison of Domain Archaea and Domain Bacteria
0:08
Overview of Archaea and Bacteria
0:09
Archaea vs. Bacteria: Nucleus, Organelles, and Organization of Genetic Material
1:45
Archaea vs. Bacteria: Cell Walls
2:20
Archaea vs. Bacteria: Number of Types of RNA Pol
2:29
Archaea vs. Bacteria: Membrane Lipids
2:53
Archaea vs. Bacteria: Introns
3:33
Bacteria: Pathogen
4:03
Bacteria: Decomposers and Fix Nitrogen
5:18
Bacteria: Aerobic, Anaerobic, Strict Anaerobes & Facultative Anaerobes
6:02
Phototrophs, Autotrophs, Heterotrophs and Chemotrophs
7:14
Phototrophs and Chemotrophs
7:50
Autotrophs and Heterotrophs
8:53
Photoautotrophs and Photoheterotrophs
10:15
Chemoautotroph and Chemoheterotrophs
11:07
Structure of Bacteria
12:21
Shapes: Cocci, Bacilli, Vibrio, and Spirochetes
12:26
Structures: Plasma Membrane and Cell Wall
14:23
Structures: Nucleoid Region, Plasmid, and Capsule Basal Apparatus, and Filament
15:30
Structures: Flagella, Basal Apparatus, Hook, and Filament
16:36
Structures: Pili, Fimbrae and Ribosome
18:00
Peptidoglycan: Gram + and Gram -
18:50
Bacterial Genomes and Reproduction
21:14
Bacterial Genomes
21:21
Reproduction of Bacteria
22:13
Transformation
23:26
Vector
24:34
Competent
25:15
Conjugation
25:53
Conjugation: F+ and R Plasmids
25:55
Example 1: Species
29:41
Example 2: Bacteria and Exchange of Genetic Material
32:31
Example 3: Ways in Which Bacteria are Beneficial to Other Organisms
33:48
Example 4: Domain Bacteria vs. Domain Archaea
34:53
Protists

1h 18m 48s

Intro
0:00
Classification of Protists
0:08
Classification of Protists
0:09
'Plant-like' Protists
2:06
'Animal-like' Protists
3:19
'Fungus-like' Protists
3:57
Serial Endosymbiosis Theory
5:15
Endosymbiosis Theory
5:33
Photosynthetic Protists
7:33
Life Cycles with a Diploid Adult
13:35
Life Cycles with a Diploid Adult
13:56
Life Cycles with a Haploid Adult
15:31
Life Cycles with a Haploid Adult
15:32
Alternation of Generations
17:22
Alternation of Generations: Multicellular Haploid & Diploid Phase
17:23
Plant-Like Protists
19:58
Euglenids
20:43
Dino Flagellates
22:57
Diatoms
26:07
Plant-Like Protists
28:44
Golden Algae
28:45
Brown Algeas
30:05
Plant-Like Protists
33:38
Red Algae
33:39
Green Algae
35:36
Green Algae: Chlamydomonus
37:44
Animal-Like Protists
40:04
Animal-Like Protists Overview
40:05
Sporozoans (Apicomplexans)
40:32
Alveolates
41:41
Sporozoans (Apicomplexans): Plasmodium & Malaria
42:59
Animal-Like Protists
48:44
Kinetoplastids
48:50
Example of Kinetoplastids: Trypanosomes & African Sleeping Sickness
49:30
Ciliate
50:42
Conjugation
53:16
Conjugation
53:26
Animal-Like Protists
57:08
Parabasilids
57:31
Diplomonads
59:06
Rhizopods
1:00:13
Forams
1:02:25
Radiolarians
1:03:28
Fungus-Like Protists
1:04:25
Fungus-Like Protists Overview
1:04:26
Slime Molds
1:05:15
Cellular Slime Molds: Feeding Stage
1:09:21
Oomycetes
1:11:15
Example 1: Alternation of Generations and Sexual Life Cycles
1:13:05
Example 2: Match Protists to Their Descriptions
1:14:12
Example 3: Three Structures that Protists Use for Motility
1:16:22
Example 4: Paramecium
1:17:04
Fungi

35m 24s

Intro
0:00
Introduction to Fungi
0:09
Introduction to Fungi
0:10
Mycologist
0:34
Examples of Fungi
0:45
Hyphae, Mycelia, Chitin, and Coencytic Fungi
2:26
Ancestral Protists
5:00
Role of Fungi in the Environment
5:35
Fungi as Decomposers
5:36
Mycorrrhiza
6:19
Lichen
8:52
Life Cycle of Fungi
11:32
Asexual Reproduction
11:33
Sexual Reproduction & Dikaryotic Cell
13:16
Chytridiomycota
18:12
Phylum Chytridiomycota
18:17
Zoospores
18:50
Zygomycota
19:07
Coenocytic & Zygomycota Life Cycle
19:08
Basidiomycota
24:27
Basidiomycota Overview
24:28
Basidiomycota Life Cycle
26:11
Ascomycota
28:00
Ascomycota Overview
28:01
Ascomycota Reproduction
28:50
Example 1: Fungi Fill in the Blank
31:02
Example 2: Name Two Roles Played by Fungi in the Environment
32:09
Example 3: Difference Between Diploid Cell and Dikaryon Cell
33:42
Example 4: Phylum of Fungi, Flagellated Spore, Coencytic
34:36
Invertebrates

1h 3m 3s

Intro
0:00
Porifera (Sponges)
0:33
Chordata
0:56
Porifera (Sponges): Sessile, Layers, Aceolomates, and Filter Feeders
1:24
Amoebocytes Cell
4:47
Choanocytes Cell
5:56
Sexual Reproduction
6:28
Cnidaria
8:05
Cnidaria Overview
8:06
Polyp & Medusa: Gastrovasular Cavity
8:29
Cnidocytes
9:42
Anthozoa
10:40
Cubozoa
11:23
Hydrozoa
11:53
Scyphoza
13:25
Platyhelminthes (Flatworms)
13:58
Flatworms: Tribloblastic, Bilateral Symmetry, and Cephalization
13:59
GI System
15:33
Excretory System
16:07
Nervous System
17:00
Turbellarians
17:36
Trematodes
18:42
Monageneans
21:32
Cestoda
21:55
Rotifera (Rotifers)
23:45
Rotifers: Digestive Tract, Pseudocoelem, and Stuctures
23:46
Reproduction: Parthenogenesis
25:33
Nematoda (Roundworms)
26:44
Nematoda (Roundworms)
26:45
Parasites: Pinworms & Hookworms
27:26
Annelida
28:36
Annelida Overview
28:37
Open Circulatory
29:21
Closed Circulatory
30:18
Nervous System
31:19
Excretory System
31:43
Oligochaete
32:07
Leeches
33:22
Polychaetes
34:42
Mollusca
35:26
Mollusca Features
35:27
Major Part 1: Visceral Mass
36:21
Major Part 2: Head-foot Region
36:49
Major Part 3: Mantle
37:13
Radula
37:49
Circulatory, Reproductive, Excretory, and Nervous System
38:14
Major Classes of Molluscs
39:12
Gastropoda
39:17
Polyplacophora
40:15
Bivales
40:41
Cephalopods
41:42
Arthropoda
43:35
Arthropoda Overview
43:36
Segmented Bodies
44:14
Exoskeleton
44:52
Jointed Appendages
45:28
Hemolyph, Excretory & Respiratory System
45:41
Myriapoda & Centipedes
47:15
Cheliceriforms
48:20
Crustcea
49:31
Herapoda
50:03
Echinodermata
52:59
Echinodermata
53:00
Watrer Vascular System
54:20
Selected Characteristics of Invertebrates
57:11
Selected Characteristics of Invertebrates
57:12
Example 1: Phylum Description
58:43
Example 2: Complex Animals
59:50
Example 3: Match Organisms to the Correct Phylum
1:01:03
Example 4: Phylum Arthropoda
1:02:01
Vertebrates

1h 7s

Intro
0:00
Phylum Chordata
0:06
Chordates Overview
0:07
Notochord and Dorsal Hollow Nerve Chord
1:24
Pharyngeal Clefts, Arches, and Post-anal Tail
3:41
Invertebrate Chordates
6:48
Lancelets
7:13
Tunicates
8:02
Hagfishes: Craniates
8:55
Vertebrate Chordates
10:41
Veterbrates Overview
10:42
Lampreys
11:00
Gnathostomes
12:20
Six Major Classes of Vertebrates
12:53
chondrichthyes
14:23
Chondrichthyes Overview
14:24
Ectothermic and Endothermic
14:42
Sharks: Lateral Line System, Neuromastsn, and Gills
15:27
Oviparous and Viviparous
17:23
Osteichthyes (Bony Fishes)
18:12
Osteichythes (Bony Fishes) Overview
18:13
Operculum
19:05
Swim Bladder
19:53
Ray-Finned Fishes
20:34
Lobe-Finned Fishes
20:58
Tetrapods
22:36
Tetrapods: Definition and Examples
22:37
Amphibians
23:53
Amphibians Overview
23:54
Order Urodela
25:51
Order Apoda
27:03
Order Anura
27:55
Reptiles
30:19
Reptiles Overview
30:20
Amniotes
30:37
Examples of Reptiles
32:46
Reptiles: Ectotherms, Gas Exchange, and Heart
33:40
Orders of Reptiles
34:17
Sphenodontia, Squamata, Testudines, and Crocodilia
34:21
Birds
36:09
Birds and Dinosaurs
36:18
Theropods
38:00
Birds: High Metabolism, Respiratory System, Lungs, and Heart
39:04
Birds: Endothermic, Bones, and Feathers
40:15
Mammals
42:33
Mammals Overview
42:35
Diaphragm and Heart
42:57
Diphydont
43:44
Synapsids
44:41
Monotremes
46:36
Monotremes
46:37
Marsupials
47:12
Marsupials: Definition and Examples
47:16
Convergent Evolution
48:09
Eutherians (Placental Mammals)
49:42
Placenta
49:43
Order Carnivora
50:48
Order Raodentia
51:00
Order Cetaceans
51:14
Primates
51:41
Primates Overview
51:42
Nails and Hands
51:58
Vision
52:51
Social Care for Young
53:28
Brain
53:43
Example 1: Distinguishing Characteristics of Chordates
54:33
Example 2: Match Description to Correct Term
55:56
Example 3: Bird's Anatomy
57:38
Example 4: Vertebrate Animal, Marine Environment, and Ectothermic
59:14
Section 9: Plants
Seedless Plants

34m 31s

Intro
0:00
Origin and Classification of Plants
0:06
Origin and Classification of Plants
0:07
Non-Vascular vs. Vascular Plants
1:29
Seedless Vascular & Seed Plants
2:28
Angiosperms & Gymnosperms
2:50
Alternation of Generations
3:54
Alternation of Generations
3:55
Bryophytes
7:58
Overview of Bryrophytes
7:59
Example: Moss Gametophyte
9:29
Example: Moss Sporophyte
9:50
Moss Life Cycle
10:12
Moss Life Cycle
10:13
Seedless Vascular Plants
13:23
Vascular Structures: Cell Walls, and Lignin
13:24
Homosporous
17:11
Heterosporous
17:48
Adaptations to Life on land
21:10
Adaptation 1: Cell Walls
21:38
Adaptation 2: Vascular Plants
21:59
Adaptation 3 : Xylem & Phloem
22:31
Adaptation 4: Seeds
23:07
Adaptation 5: Pollen
23:35
Adaptation 6: Stomata
24:45
Adaptation 7: Reduced Gametophyte Generation
25:32
Example 1: Bryophytes
26:39
Example 2: Sporangium, Lignin, Gametophyte, and Antheridium
28:34
Example 3: Adaptations to Life on Land
29:47
Example 4: Life Cycle of Plant
32:06
Plant Structure

1h 1m 21s

Intro
0:00
Plant Tissue
0:05
Dermal Tissue
0:15
Vascular Tissue
0:39
Ground Tissue
1:31
Cell Types in Plants
2:14
Parenchyma Cells
2:24
Collenchyma Cells
3:21
Sclerenchyma Cells
3:59
Xylem
5:04
Xylem: Tracheids and Vessel Elements
6:12
Gymnosperms vs. Angiosperms
7:53
Phloem
8:37
Phloem: Structures and Function
8:38
Sieve-Tube Elements
8:45
Companion Cells & Sieve Plates
9:11
Roots
10:08
Taproots & Fibrous
10:09
Aerial Roots & Prop Roots
11:41
Structures and Functions of Root: Dicot & Monocot
13:00
Pericyle
16:57
The Nitrogen Cylce
18:05
The Nitrogen Cycle
18:06
Mycorrhizae
24:20
Mycorrhizae
24:23
Ectomycorrhiza
26:03
Endomycorrhiza
26:25
Stems
26:53
Stems
26:54
Vascular Bundles of Monocots and Dicots
28:18
Leaves
29:48
Blade & Petiole
30:13
Upper Epidermis, Lower Epidermis & Cuticle
30:39
Ground Tissue, Palisade Mesophyll, Spongy Mesophyll
31:35
Stomata Pores
33:23
Guard Cells
34:15
Vascular Tissues: Vascular Bundles and Bundle Sheath
34:46
Stomata
36:12
Stomata & Gas Exchange
36:16
Guard Cells, Flaccid, and Turgid
36:43
Water Potential
38:03
Factors for Opening Stoma
40:35
Factors Causing Stoma to Close
42:44
Overview of Plant Growth
44:23
Overview of Plant Growth
44:24
Primary Plant Growth
46:19
Apical Meristems
46:25
Root Growth: Zone of Cell Division
46:44
Root Growth: Zone of Cell Elongation
47:35
Root Growth: Zone of Cell Differentiation
47:55
Stem Growth: Leaf Primodia
48:16
Secondary Plant Growth
48:48
Secondary Plant Growth Overview
48:59
Vascular Cambium: Secondary Xylem and Phloem
49:38
Cork Cambium: Periderm and Lenticels
51:10
Example 1: Leaf Structures
53:30
Example 2: List Three Types of Plant Tissue and their Major Functions
55:13
Example 3: What are Two Factors that Stimulate the Opening or Closing of Stomata?
56:58
Example 4: Plant Growth
59:18
Gymnosperms and Angiosperms

1h 1m 51s

Intro
0:00
Seed Plants
0:22
Sporopollenin
0:58
Heterosporous: Megasporangia
2:49
Heterosporous: Microsporangia
3:19
Gymnosperms
5:20
Gymnosperms
5:21
Gymnosperm Life Cycle
7:30
Gymnosperm Life Cycle
7:31
Flower Structure
15:15
Petal & Pollination
15:48
Sepal
16:52
Stamen: Anther, Filament
17:05
Pistill: Stigma, Style, Ovule, Ovary
17:55
Complete Flowers
20:14
Angiosperm Gametophyte Formation
20:47
Male Gametophyte: Microsporocytes, Microsporangia & Meiosis
20:57
Female Gametophyte: Megasporocytes & Meiosis
24:22
Double Fertilization
25:43
Double Fertilization: Pollen Tube and Endosperm
25:44
Angiosperm Life Cycle
29:43
Angiosperm Life Cycle
29:48
Seed Structure and Development
33:37
Seed Structure and Development
33:38
Pollen Dispersal
37:53
Abiotic
38:28
Biotic
39:30
Prevention of Self-Pollination
40:48
Mechanism 1
41:08
Mechanism 2: Dioecious
41:37
Mechanism 3
42:32
Self-Incompatibility
43:08
Gametophytic Self-Incompatibility
44:38
Sporophytic Self-Incompatibility
46:50
Asexual Reproduction
48:33
Asexual Reproduction & Vegetative Propagation
48:34
Graftiry
50:19
Monocots and Dicots
51:34
Monocots vs.Dicots
51:35
Example 1: Double Fertilization
54:43
Example 2: Mechanisms of Self-Fertilization
56:02
Example 3: Monocots vs. Dicots
58:11
Example 4: Flower Structures
1:00:11
Transport of Nutrients and Water in Plants

40m 30s

Intro
0:00
Review of Plant Cell Structure
0:14
Cell Wall, Plasma Membrane, Middle lamella, and Cytoplasm
0:15
Plasmodesmata, Chloroplasts, and Central Vacuole
3:24
Water Absorption by Plants
4:28
Root Hairs and Mycorrhizae
4:30
Osmosis and Water Potential
5:41
Apoplast and Symplast Pathways
10:01
Apoplast and Symplast Pathways
10:02
Xylem Structure
21:02
Tracheids and Vessel Elements
21:03
Bulk Flow
23:00
Transpiration
23:26
Cohesion
25:10
Adhesion
26:10
Phloem Structure
27:25
Pholem
27:26
Sieve-Tube Elements
27:48
Companion Cells
28:17
Translocation
28:42
Sugar Source and Sugar Sink Overview
28:43
Example of Sugar Sink
30:01
Example of Sugar Source
30:48
Example 1: Match the Following Terms to their Description
33:17
Example 2: Water Potential
34:58
Example 3: Bulk Flow
36:56
Example 4: Sugar Sink and Sugar Source
38:33
Plant Hormones and Tropisms

48m 10s

Intro
0:00
Plant Cell Signaling
0:17
Plant Cell Signaling Overview
0:18
Step 1: Reception
1:03
Step 2: Transduction
2:32
Step 3: Response
2:58
Second Messengers
3:52
Protein Kinases
4:42
Auxins
6:14
Auxins
6:18
Indoleacetic Acid (IAA)
7:23
Cytokinins and Gibberellins
11:10
Cytokinins: Apical Dominance & Delay of Aging
11:16
Gibberellins: 'Bolting'
13:51
Ethylene
15:33
Ethylene
15:34
Positive Feedback
15:46
Leaf Abscission
18:05
Mechanical Stress: Triple Response
19:36
Abscisic Acid
21:10
Abscisic Acid
21:15
Tropisms
23:11
Positive Tropism
23:50
Negative Tropism
24:07
Statoliths
26:21
Phytochromes and Photoperiodism
27:48
Phytochromes: PR and PFR
27:56
Circadian Rhythms
32:06
Photoperiod
33:13
Photoperiodism
33:38
Gerner & Allard
34:35
Short-Day Plant
35:22
Long-Day Plant
37:00
Example 1: Plant Hormones
41:28
Example 2: Cytokinins & Gibberellins
43:00
Example 3: Match the Following Terms to their Description
44:46
Example 4: Hormones & Cell Response
46:14
Section 10: Animal Structure and Physiology
The Respiratory System

48m 14s

Intro
0:00
Gas Exchange in Animals
0:17
Respiration
0:19
Ventilation
1:09
Characteristics of Respiratory Surfaces
1:53
Gas Exchange in Aquatic Animals
3:05
Simple Aquatic Animals
3:06
Gills & Gas Exchange in Complex Aquatic Animals
3:49
Countercurrent Exchange
6:12
Gas Exchange in Terrestrial Animals
13:46
Earthworms
14:07
Internal Respiratory
15:35
Insects
16:55
Circulatory Fluid
19:06
The Human Respiratory System
21:21
Nasal Cavity, Pharynx, Larynx, and Epiglottis
21:50
Bronchus, Bronchiole, Trachea, and Alveoli
23:38
Pulmonary Surfactants
28:05
Circulatory System: Hemoglobin
29:13
Ventilation
30:28
Inspiration/Expiration: Diaphragm, Thorax, and Abdomen
30:33
Breathing Control Center: Regulation of pH
34:34
Example 1: Tracheal System in Insects
39:08
Example 2: Countercurrent Exchange
42:09
Example 3: Respiratory System
44:10
Example 4: Diaphragm, Ventilation, pH, and Regulation of Breathing
45:31
The Circulatory System

1h 20m 21s

Intro
0:00
Types of Circulatory Systems
0:07
Circulatory System Overview
0:08
Open Circulatory System
3:19
Closed Circulatory System
5:58
Blood Vessels
7:51
Arteries
8:16
Veins
10:01
Capillaries
12:35
Vasoconstriction and Vasodilation
13:10
Vasoconstriction
13:11
Vasodilation
13:47
Thermoregulation
14:32
Blood
15:53
Plasma
15:54
Cellular Component: Red Blood Cells
17:41
Cellular Component: White Blood Cells
20:18
Platelets
21:14
Blood Types
21:35
Clotting
27:04
Blood, Fibrin, and Clotting
27:05
Hemophilia
30:26
The Heart
31:09
Structures and Functions of the Heart
31:19
Pulmonary and Systemic Circulation
40:20
Double Circuit: Pulmonary Circuit and Systemic Circuit
40:21
The Cardiac Cycle
42:35
The Cardiac Cycle
42:36
Autonomic Nervous System
50:00
Hemoglobin
51:25
Hemoglobin & Hemocyanin
51:26
Oxygen-Hemoglobin Dissociation Curve
55:30
Oxygen-Hemoglobin Dissociation Curve
55:44
Transport of Carbon Dioxide
1:06:31
Transport of Carbon Dioxide
1:06:37
Example 1: Pathway of Blood
1:12:48
Example 2: Oxygenated Blood, Pacemaker, and Clotting
1:15:24
Example 3: Vasodilation and Vasoconstriction
1:16:19
Example 4: Oxygen-Hemoglobin Dissociation Curve
1:18:13
The Digestive System

56m 11s

Intro
0:00
Introduction to Digestion
0:07
Digestive Process
0:08
Intracellular Digestion
0:45
Extracellular Digestion
1:44
Types of Digestive Tracts
2:08
Gastrovascular Cavity
2:09
Complete Gastrointestinal Tract (Alimentary Canal)
3:54
'Crop'
4:43
The Human Digestive System
5:41
Structures of the Human Digestive System
5:47
The Oral Cavity and Esophagus
7:47
Mechanical & Chemical Digestion
7:48
Salivary Glands
8:55
Pharynx and Epigloltis
9:43
Peristalsis
11:35
The Stomach
12:57
Lower Esophageal Sphincter
13:00
Gastric Gland, Parietal Cells, and Pepsin
14:32
Mucus Cell
15:48
Chyme & Pyloric Sphincter
17:32
The Pancreas
18:31
Endocrine and Exocrine
19:03
Amylase
20:05
Proteases
20:51
Lipases
22:20
The Liver
23:08
The Liver & Production of Bile
23:09
The Small Intestine
24:37
The Small Intestine
24:38
Duodenum
27:44
Intestinal Enzymes
28:41
Digestive Enzyme
33:30
Site of Production: Mouth
33:43
Site of Production: Stomach
34:03
Site of Production: Pancreas
34:16
Site of Production: Small Intestine
36:18
Absorption of Nutrients
37:51
Absorption of Nutrients: Jejunum and Ileum
37:52
The Large Intestine
44:52
The Large Intestine: Colon, Cecum, and Rectum
44:53
Regulation of Digestion by Hormones
46:55
Gastrin
47:21
Secretin
47:50
Cholecystokinin (CCK)
48:00
Example 1: Intestinal Cell, Bile, and Digestion of Fats
48:29
Example 2: Matching
51:06
Example 3: Digestion and Absorption of Starch
52:18
Example 4: Large Intestine and Gastric Fluids
54:52
The Excretory System

1h 12m 14s

Intro
0:00
Nitrogenous Wastes
0:08
Nitrogenous Wastes Overview
0:09
NH3
0:39
Urea
2:43
Uric Acid
3:31
Osmoregulation
4:56
Osmoregulation
5:05
Saltwater Fish vs. Freshwater Fish
8:58
Types of Excretory Systems
13:42
Protonephridia
13:50
Metanephridia
16:15
Malpighian Tubule
19:05
The Human Excretory System
20:45
Kidney, Ureter, bladder, Urethra, Medula, and Cortex
20:53
Filtration, Reabsorption and Secretion
22:53
Filtration
22:54
Reabsorption
24:16
Secretion
25:20
The Nephron
26:23
The Nephron
26:24
The Nephron, cont.
41:45
Descending Loop of Henle
41:46
Ascending Loop of Henle
45:45
Antidiuretic Hormone
54:30
Antidiuretic Hormone (ADH)
54:31
Aldosterone
58:58
Aldosterone
58:59
Example 1: Nephron of an Aquatic Mammal
1:04:21
Example 2: Uric Acid & Saltwater Fish
1:06:36
Example 3: Nephron
1:09:14
Example 4: Gastrointestinal Infection
1:10:41
The Endocrine System

51m 12s

Intro
0:00
The Endocrine System Overview
0:07
Thyroid
0:08
Exocrine
1:56
Pancreas
2:44
Paracrine Signaling
4:06
Pheromones
5:15
Mechanisms of Hormone Action
6:06
Reception, Transduction, and Response
7:06
Classes of Hormone
10:05
Negative Feedback: Testosterone Example
12:16
The Pancreas
15:11
The Pancreas & islets of Langerhan
15:12
Insulin
16:02
Glucagon
17:28
The Anterior Pituitary
19:25
Thyroid Stimulating Hormone
20:24
Adrenocorticotropic Hormone
21:16
Follide Stimulating Hormone
22:04
Luteinizing Hormone
22:45
Growth Hormone
23:45
Prolactin
24:24
Melanocyte Stimulating Hormone
24:55
The Hypothalamus and Posterior Pituitary
25:45
Hypothalamus, Oxytocin, Antidiuretic Hormone (ADH), and Posterior Pituitary
25:46
The Adrenal Glands
31:20
Adrenal Cortex
31:56
Adrenal Medulla
34:29
The Thyroid
35:54
Thyroxine
36:09
Calcitonin
40:27
The Parathyroids
41:44
Parathyroids Hormone (PTH)
41:45
The Ovaries and Testes
43:32
Estrogen, Progesterone, and Testosterone
43:33
Example 1: Match the Following Hormones with their Descriptions
45:38
Example 2: Pancreas, Endocrine Organ & Exocrine Organ
47:06
Example 3: Insulin and Glucagon
48:28
Example 4: Increased Level of Cortisol in Blood
50:25
The Nervous System

1h 10m 38s

Intro
0:00
Types of Nervous Systems
0:28
Nerve Net
0:37
Flatworm
1:07
Cephalization
1:52
Arthropods
2:44
Echinoderms
3:11
Nervous System Organization
3:40
Nervous System Organization Overview
3:41
Automatic Nervous System: Sympathetic & Parasympathetic
4:42
Neuron Structure
6:57
Cell Body & Dendrites
7:16
Axon & Axon Hillock
8:20
Synaptic Terminals, Mylenin, and Nodes of Ranvier
9:01
Pre-synaptic and Post-synaptic Cells
10:16
Pre-synaptic Cells
10:17
Post-synaptic Cells
11:05
Types of Neurons
11:50
Sensory Neurons
11:54
Motor Neurons
13:12
Interneurons
14:24
Resting Potential
15:14
Membrane Potential
15:25
Resting Potential: Chemical Gradient
16:06
Resting Potential: Electrical Gradient
19:18
Gated Ion Channels
24:40
Voltage-Gated & Ligand-Gated Ion Channels
24:48
Action Potential
30:09
Action Potential Overview
30:10
Step 1
32:07
Step 2
32:17
Step 3
33:12
Step 4
35:14
Step 5
36:39
Action Potential Transmission
39:04
Action Potential Transmission
39:05
Speed of Conduction
41:19
Saltatory Conduction
42:58
The Synapse
44:17
The Synapse: Presynaptic & Postsynaptic Cell
44:31
Examples of Neurotransmitters
50:05
Brain Structure
51:57
Meniges
52:19
Cerebrum
52:56
Corpus Callosum
53:13
Gray & White Matter
53:38
Cerebral Lobes
55:35
Cerebellum
56:00
Brainstem
56:30
Medulla
56:51
Pons
57:22
Midbrain
57:55
Thalamus
58:25
Hypothalamus
58:58
Ventricles
59:51
The Spinal Cord
1:00:29
Sensory Stimuli
1:00:30
Reflex Arc
1:01:41
Example 1: Automatic Nervous System
1:04:38
Example 2: Synaptic Terminal and the Release of Neurotransmitters
1:06:22
Example 3: Volted-Gated Ion Channels
1:08:00
Example 4: Neuron Structure
1:09:26
Musculoskeletal System

39m 29s

Intro
0:00
Skeletal System Types and Function
0:30
Skeletal System
0:31
Exoskeleton
1:34
Endoskeleton
2:32
Skeletal System Components
2:55
Bone
3:06
Cartilage
5:04
Tendons
6:18
Ligaments
6:34
Skeletal Muscle
6:52
Skeletal Muscle
7:24
Sarcomere
9:50
The Sliding Filament Theory
13:12
The Sliding Filament Theory: Muscle Contraction
13:13
The Neuromuscular Junction
17:24
The Neuromuscular Junction: Motor Neuron & Muscle Fiber
17:26
Sarcolemma, Sarcoplasmic
21:54
Tropomyosin & Troponin
23:35
Summation and Tetanus
25:26
Single Twitch, Summation of Two Twitches, and Tetanus
25:27
Smooth Muscle
28:50
Smooth Muscle
28:58
Cardiac Muscle
30:40
Cardiac Muscle
30:42
Summary of Muscle Types
32:07
Summary of Muscle Types
32:08
Example 1: Contraction and Skeletal Muscle
33:15
Example 2: Skeletal Muscle and Smooth Muscle
36:23
Example 3: Muscle Contraction, Bone, and Nonvascularized Connective Tissue
37:31
Example 4: Sarcomere
38:17
The Immune System

1h 24m 28s

Intro
0:00
The Lymphatic System
0:16
The Lymphatic System Overview
0:17
Function 1
1:23
Function 2
2:27
Barrier Defenses
3:41
Nonspecific vs. Specific Immune Defenses
3:42
Barrier Defenses
5:12
Nonspecific Cellular Defenses
7:50
Nonspecific Cellular Defenses Overview
7:53
Phagocytes
9:29
Neutrophils
11:43
Macrophages
12:15
Natural Killer Cells
12:55
Inflammatory Response
14:19
Complement
18:16
Interferons
18:40
Specific Defenses - Acquired Immunity
20:12
T lymphocytes and B lymphocytes
20:13
B Cells
23:35
B Cells & Humoral Immunity
23:41
Clonal Selection
29:50
Clonal Selection
29:51
Primary Immune Response
34:28
Secondary Immune Response
35:31
Cytotoxic T Cells
38:41
Helper T Cells
39:20
Major Histocompatibility Complex Molecules
40:44
Major Histocompatibility Complex Molecules
40:55
Helper T Cells
52:36
Helper T Cells
52:37
Mechanisms of Antibody Action
59:00
Mechanisms of Antibody Action
59:01
Opsonization
1:00:01
Complement System
1:01:57
Classes of Antibodies
1:02:45
IgM
1:03:01
IgA
1:03:17
IgG
1:03:53
IgE
1:04:10
Passive and Active Immunity
1:05:00
Passive Immunity
1:05:01
Active Immunity
1:07:49
Recognition of Self and Non-Self
1:09:32
Recognition of Self and Non-Self
1:09:33
Self-Tolerance & Autoimmune Diseases
1:10:50
Immunodeficiency
1:13:27
Immunodeficiency
1:13:28
Chemotherapy
1:13:56
AID
1:14:27
Example 1: Match the Following Terms with their Descriptions
1:15:26
Example 2: Three Components of Non-specific Immunity
1:17:59
Example 3: Immunodeficient
1:21:19
Example 4: Self-tolerance and Autoimmune Diseases
1:23:07
Section 11: Animal Reproduction and Development
Reproduction

1h 1m 41s

Intro
0:00
Asexual Reproduction
0:17
Fragmentation
0:53
Fission
1:54
Parthenogenesis
2:38
Sexual Reproduction
4:00
Sexual Reproduction
4:01
Hermaphrodite
8:08
The Male Reproduction System
8:54
Seminiferous Tubules & Leydig Cells
8:55
Epididymis
9:48
Seminal Vesicle
11:19
Bulbourethral
12:37
The Female Reproductive System
13:25
Ovaries
13:28
Fallopian
14:50
Endometrium, Uterus, Cilia, and Cervix
15:03
Mammary Glands
16:44
Spermatogenesis
17:08
Spermatogenesis
17:09
Oogenesis
21:01
Oogenesis
21:02
The Menstrual Cycle
27:56
The Menstrual Cycle: Ovarian and Uterine Cycle
27:57
Summary of the Ovarian and Uterine Cycles
42:54
Ovarian
42:55
Uterine
44:51
Oxytocin and Prolactin
46:33
Oxytocin
46:34
Prolactin
47:00
Regulation of the Male Reproductive System
47:28
Hormones: GnRH, LH, FSH, and Testosterone
47:29
Fertilization
50:11
Fertilization
50:12
Structures of Egg
50:28
Acrosomal Reaction
51:36
Cortical Reaction
53:09
Example 1: List Three Differences between Spermatogenesis and oogenesis
55:36
Example 2: Match the Following Terms to their Descriptions
57:34
Example 3: Pregnancy and the Ovarian Cycle
58:44
Example 4: Hormone
1:00:43
Development

50m 5s

Intro
0:00
Cleavage
0:31
Cleavage
0:32
Meroblastic
2:06
Holoblastic Cleavage
3:23
Protostomes
4:34
Deuterostomes
5:13
Totipotent
5:52
Blastula Formation
6:42
Blastula
6:46
Gastrula Formation
8:12
Deuterostomes
11:02
Protostome
11:44
Ectoderm
12:17
Mesoderm
12:55
Endoderm
13:40
Cytoplasmic Determinants
15:19
Cytoplasmic Determinants
15:23
The Bird Embryo
22:52
Cleavage
23:35
Blastoderm
23:55
Primitive Streak
25:38
Migration and Differentiation
27:09
Extraembryonic Membranes
28:33
Extraembryonic Membranes
28:34
Chorion
30:02
Yolk Sac
30:36
Allantois
31:04
The Mammalian Embryo
32:18
Cleavage
32:28
Blastocyst
32:44
Trophoblast
34:37
Following Implantation
35:48
Organogenesis
37:04
Organogenesis, Notochord and Neural Tube
37:05
Induction
40:15
Induction
40:39
Fate Mapping
41:40
Example 1: Processes and Stages of Embryological Development
42:49
Example 2: Transplanted Cells
44:33
Example 3: Germ Layer
46:41
Example 4: Extraembryonic Membranes
47:28
Section 12: Animal Behavior
Animal Behavior

47m 48s

Intro
0:00
Introduction to Animal Behavior
0:05
Introduction to Animal Behavior
0:06
Ethology
1:04
Proximate Cause & Ultimate Cause
1:46
Fixed Action Pattern
3:07
Sign Stimulus
3:40
Releases and Example
3:55
Exploitation and Example
7:23
Learning
8:56
Habituation, Associative Learning, and Imprinting
8:57
Habituation
10:03
Habituation: Definition and Example
10:04
Associative Learning
11:47
Classical
12:19
Operant Conditioning
13:40
Positive & Negative Reinforcement
14:59
Positive & Negative Punishment
16:13
Extinction
17:28
Imprinting
17:47
Imprinting: Definition and Example
17:48
Social Behavior
20:12
Cooperation
20:38
Agonistic
21:37
Dorminance Heirarchies
23:23
Territoriality
24:08
Altruism
24:55
Communication
26:56
Communication
26:57
Mating
32:38
Mating Overview
32:40
Promiscuous
33:13
Monogamous
33:32
Polygamous
33:48
Intrasexual
34:22
Intersexual Selection
35:08
Foraging
36:08
Optimal Foraging Model
36:39
Foraging
37:47
Movement
39:12
Kinesis
39:20
Taxis
40:17
Migration
40:54
Lunar Cycles
42:02
Lunar Cycles
42:08
Example 1: Types of Conditioning
43:19
Example 2: Match the Following Terms to their Descriptions
44:12
Example 3: How is the Optimal Foraging Model Used to Explain Foraging Behavior
45:47
Example 4: Learning
46:54
Section 13: Ecology
Biomes

58m 49s

Intro
0:00
Ecology
0:08
Ecology
0:14
Environment
0:22
Integrates
1:41
Environment Impacts
2:20
Population and Distribution
3:20
Population
3:21
Range
4:50
Potential Range
5:10
Abiotic
5:46
Biotic
6:22
Climate
7:55
Temperature
8:40
Precipitation
10:00
Wind
10:37
Sunlight
10:54
Macroclimates & Microclimates
11:31
Other Abiotic Factors
12:20
Geography
12:28
Water
13:17
Soil and Rocks
13:48
Sunlight
14:42
Sunlight
14:43
Seasons
15:43
June Solstice, December Solstice, March Equinox, and September Equinox
15:44
Tropics
19:00
Seasonability
19:39
Wind and Weather Patterns
20:44
Vertical Circulation
20:51
Surface Wind Patterns
25:18
Local Climate Effects
26:51
Local Climate Effects
26:52
Terrestrial Biomes
30:04
Biome
30:05
Forest
31:02
Tropical Forest
32:00
Tropical Forest
32:01
Temperate Broadleaf Forest
32:55
Temperate Broadleaf Forest
32:56
Coniferous/Taiga Forest
34:10
Coniferous/Taiga Forest
34:11
Desert
36:05
Desert
36:06
Grassland
37:45
Grassland
37:46
Tundra
40:09
Tundra
40:10
Freshwater Biomes
42:25
Freshwater Biomes: Zones
42:27
Eutrophic Lakes
44:24
Oligotrophic Lakes
45:01
Lakes Turnover
46:03
Rivers
46:51
Wetlands
47:40
Estuary
48:11
Marine Biomes
48:45
Marine Biomes: Zones
48:46
Example 1: Diversity of Life
52:18
Example 2: Marine Biome
53:08
Example 3: Season
54:20
Example 4: Biotic vs. Abiotic
55:54
Population

41m 16s

Intro
0:00
Population
0:07
Size 'N'
0:16
Density
0:41
Dispersion
1:01
Measure Population: Count Individuals, Sampling, and Proxymeasure
2:26
Mortality
7:29
Mortality and Survivorship
7:30
Age Structure Diagrams
11:52
Expanding with Rapid Growth, Expanding, and Stable
11:58
Population Growth
15:39
Biotic Potential & Exponential Growth
15:43
Logistic Population Growth
19:07
Carrying Capacity (K)
19:18
Limiting Factors
20:55
Logistic Model and Oscillation
22:55
Logistic Model and Oscillation
22:56
Changes to the Carrying Capacity
24:36
Changes to the Carrying Capacity
24:37
Growth Strategies
26:07
'r-selected' or 'r-strategist'
26:23
'K-selected' or 'K-strategist'
27:47
Human Population
30:15
Human Population and Exponential Growth
30:21
Case Study - Lynx and Hare
31:54
Case Study - Lynx and Hare
31:55
Example 1: Estimating Population Size
34:35
Example 2: Population Growth
36:45
Example 3: Carrying Capacity
38:17
Example 4: Types of Dispersion
40:15
Communities

1h 6m 26s

Intro
0:00
Community
0:07
Ecosystem
0:40
Interspecific Interactions
1:14
Competition
2:45
Competition Overview
2:46
Competitive Exclusion
3:57
Resource Partitioning
4:45
Character Displacement
6:22
Predation
7:46
Predation
7:47
True Predation
8:05
Grazing/ Herbivory
8:39
Predator Adaptation
10:13
Predator Strategies
10:22
Physical Features
11:02
Prey Adaptation
12:14
Prey Adaptation
12:23
Aposematic Coloration
13:35
Batesian Mimicry
14:32
Size
15:42
Parasitism
16:48
Symbiotic Relationship
16:54
Ectoparasites
18:31
Endoparasites
18:53
Hyperparisitism
19:21
Vector
20:08
Parasitoids
20:54
Mutualism
21:23
Resource - Resource mutualism
21:34
Service - Resource Mutualism
23:31
Service - Service Mutualism: Obligate & Facultative
24:23
Commensalism
26:01
Commensalism
26:03
Symbiosis
27:31
Trophic Structure
28:35
Producers & Consumers: Autotrophs & Heterotrophs
28:36
Food Chain
33:26
Producer & Consumers
33:38
Food Web
39:01
Food Web
39:06
Significant Species within Communities
41:42
Dominant Species
41:50
Keystone Species
42:44
Foundation Species
43:41
Community Dynamics and Disturbances
44:31
Disturbances
44:33
Duration
47:01
Areal Coverage
47:22
Frequency
47:48
Intensity
48:04
Intermediate Level of Disturbance
48:20
Ecological Succession
50:29
Primary and Secondary Ecological Succession
50:30
Example 1: Competition Situation & Outcome
57:18
Example 2: Food Chains
1:00:08
Example 3: Ecological Units
1:02:44
Example 4: Disturbances & Returning to the Original Climax Community
1:04:30
Energy and Ecosystems

57m 42s

Intro
0:00
Ecosystem: Biotic & Abiotic Components
0:15
First Law of Thermodynamics & Energy Flow
0:40
Gross Primary Productivity (GPP)
3:52
Net Primary Productivity (NPP)
4:50
Biogeochemical Cycles
7:16
Law of Conservation of Mass & Biogeochemical Cycles
7:17
Water Cycle
10:55
Water Cycle
10:57
Carbon Cycle
17:52
Carbon Cycle
17:53
Nitrogen Cycle
22:40
Nitrogen Cycle
22:41
Phosphorous Cycle
29:34
Phosphorous Cycle
29:35
Climate Change
33:20
Climate Change
33:21
Eutrophication
39:38
Nitrogen
40:34
Phosphorous
41:29
Eutrophication
42:55
Example 1: Energy and Ecosystems
45:28
Example 2: Atmospheric CO2
48:44
Example 3: Nitrogen Cycle
51:22
Example 4: Conversion of a Forest near a Lake to Farmland
53:20
Section 14: Laboratory Review
Laboratory Review

2h 4m 30s

Intro
0:00
Lab 1: Diffusion and Osmosis
0:09
Lab 1: Diffusion and Osmosis
0:10
Lab 1: Water Potential
11:55
Lab 1: Water Potential
11:56
Lab 2: Enzyme Catalysis
18:30
Lab 2: Enzyme Catalysis
18:31
Lab 3: Mitosis and Meiosis
27:40
Lab 3: Mitosis and Meiosis
27:41
Lab 3: Mitosis and Meiosis
31:50
Ascomycota Life Cycle
31:51
Lab 4: Plant Pigments and Photosynthesis
40:36
Lab 4: Plant Pigments and Photosynthesis
40:37
Lab 5: Cell Respiration
49:56
Lab 5: Cell Respiration
49:57
Lab 6: Molecular Biology
55:06
Lab 6: Molecular Biology & Transformation 1st Part
55:07
Lab 6: Molecular Biology
1:01:16
Lab 6: Molecular Biology 2nd Part
1:01:17
Lab 7: Genetics of Organisms
1:07:32
Lab 7: Genetics of Organisms
1:07:33
Lab 7: Chi-square Analysis
1:13:00
Lab 7: Chi-square Analysis
1:13:03
Lab 8: Population Genetics and Evolution
1:20:41
Lab 8: Population Genetics and Evolution
1:20:42
Lab 9: Transpiration
1:24:02
Lab 9: Transpiration
1:24:03
Lab 10: Physiology of the Circulatory System
1:31:05
Lab 10: Physiology of the Circulatory System
1:31:06
Lab 10: Temperature and Metabolism in Ectotherms
1:38:25
Lab 10: Temperature and Metabolism in Ectotherms
1:38:30
Lab 11: Animal Behavior
1:40:52
Lab 11: Animal Behavior
1:40:53
Lab 12: Dissolved Oxygen & Aquatic Primary Productivity
1:45:36
Lab 12: Dissolved Oxygen & Aquatic Primary Productivity
1:45:37
Lab 12: Primary Productivity
1:49:06
Lab 12: Primary Productivity
1:49:07
Example 1: Chi-square Analysis
1:56:31
Example 2: Mitosis
1:59:28
Example 3: Transpiration of Plants
2:00:27
Example 4: Population Genetic
2:01:16
Section 15: The AP Biology Test
Understanding the Basics

13m 2s

Intro
0:00
AP Biology Structure
0:18
Section I
0:31
Section II
1:16
Scoring
2:04
The Four 'Big Ideas'
3:51
Process of Evolution
4:37
Biological Systems Utilize
4:44
Living Systems
4:55
Biological Systems Interact
5:03
Items to Bring to the Test
7:56
Test Taking Tips
9:53
Section 16: Practice Test (Barron's 4th Edition)
AP Biology Practice Exam: Section I, Part A, Multiple Choice Questions 1-31

1h 4m 29s

Intro
0:00
AP Biology Practice Exam
0:14
Multiple Choice 1
0:40
Multiple Choice 2
2:27
Multiple Choice 3
4:30
Multiple Choice 4
6:43
Multiple Choice 5
9:27
Multiple Choice 6
11:32
Multiple Choice 7
12:54
Multiple Choice 8
14:42
Multiple Choice 9
17:06
Multiple Choice 10
18:42
Multiple Choice 11
20:49
Multiple Choice 12
23:23
Multiple Choice 13
26:20
Multiple Choice 14
27:52
Multiple Choice 15
28:44
Multiple Choice 16
33:07
Multiple Choice 17
35:31
Multiple Choice 18
39:43
Multiple Choice 19
40:37
Multiple Choice 20
42:47
Multiple Choice 21
45:58
Multiple Choice 22
49:49
Multiple Choice 23
53:44
Multiple Choice 24
55:12
Multiple Choice 25
55:59
Multiple Choice 26
56:50
Multiple Choice 27
58:08
Multiple Choice 28
59:54
Multiple Choice 29
1:01:36
Multiple Choice 30
1:02:31
Multiple Choice 31
1:03:50
AP Biology Practice Exam: Section I, Part A, Multiple Choice Questions 32-63

50m 44s

Intro
0:00
AP Biology Practice Exam
0:14
Multiple Choice 32
0:27
Multiple Choice 33
4:14
Multiple Choice 34
5:12
Multiple Choice 35
6:51
Multiple Choice 36
10:46
Multiple Choice 37
11:27
Multiple Choice 38
12:17
Multiple Choice 39
13:49
Multiple Choice 40
17:02
Multiple Choice 41
18:27
Multiple Choice 42
19:35
Multiple Choice 43
21:10
Multiple Choice 44
23:35
Multiple Choice 45
25:00
Multiple Choice 46
26:20
Multiple Choice 47
28:40
Multiple Choice 48
30:14
Multiple Choice 49
31:24
Multiple Choice 50
32:45
Multiple Choice 51
33:41
Multiple Choice 52
34:40
Multiple Choice 53
36:12
Multiple Choice 54
38:06
Multiple Choice 55
38:37
Multiple Choice 56
40:00
Multiple Choice 57
41:18
Multiple Choice 58
43:12
Multiple Choice 59
44:25
Multiple Choice 60
45:02
Multiple Choice 61
46:10
Multiple Choice 62
47:54
Multiple Choice 63
49:01
AP Biology Practice Exam: Section I, Part B, Grid In

21m 52s

Intro
0:00
AP Biology Practice Exam
0:17
Grid In Question 1
0:29
Grid In Question 2
3:49
Grid In Question 3
11:04
Grid In Question 4
13:18
Grid In Question 5
17:01
Grid In Question 6
19:30
AP Biology Practice Exam: Section II, Long Free Response Questions

31m 22s

Intro
0:00
AP Biology Practice Exam
0:18
Free Response 1
0:29
Free Response 2
20:47
AP Biology Practice Exam: Section II, Short Free Response Questions

24m 41s

Intro
0:00
AP Biology Practice Exam
0:15
Free Response 3
0:26
Free Response 4
5:21
Free Response 5
8:25
Free Response 6
11:38
Free Response 7
14:48
Free Response 8
22:14
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Lecture Comments (15)

1 answer

Last reply by: Dr Carleen Eaton
Thu Apr 28, 2016 10:59 AM

Post by Kristy Osborne on April 17, 2016

Am I able to skip ahead of the lecture all I want to listen to is tolerance.

1 answer

Last reply by: Dr Carleen Eaton
Wed Mar 26, 2014 6:36 PM

Post by Fadel Hanoun on December 8, 2013

You are amazing!

1 answer

Last reply by: Dr Carleen Eaton
Wed Feb 20, 2013 4:18 PM

Post by bo young lee on February 5, 2013

i keep dont know the how endocrine system and immune system and lymph system differences

0 answers

Post by Matt F on January 16, 2013

Girl you blowin' up! yew!
Sick vids, thank you.

1 answer

Last reply by: Dr Carleen Eaton
Sun Oct 21, 2012 10:32 PM

Post by Sarah Wilson on October 20, 2012

These videos are wonderful, thank you.

1 answer

Last reply by: Dr Carleen Eaton
Thu Jun 9, 2011 6:32 PM

Post by Daniela Valencia on June 4, 2011

Dr Carleen,

love your videos!! :))
Great teacher.

Thank you!

3 answers

Last reply by: Dr Carleen Eaton
Wed Apr 20, 2011 4:10 PM

Post by Billy Jay on April 19, 2011

Hi Dr. Eaton,

Is the term "Lysozyme" a generalized word used to describe sugar-degrading enzymes. The reason I ask is because around 10:40 you mention that Lysozymes are contained in Lysosomes, but I can't find any online source to confirm that. However, various sources do say that amylases (among other types of enzymes) ARE found in Lysosomes. I was wondering if they're they same thing.

The Immune System

  • The first line of defense is barrier to entry. The skin, mucus membranes and tears are barrier defenses.
  • The second line of defense includes nonspecific cellular defenses such as neutrophils, macrophages and natural killer cells. Proteins such as complement and interferon also play a role in nonspecific defense.
  • B cells are produced and mature in the bone marrow. B cells are responsible for humoral immunity, which is mediated by antibodies secreted by plasma cells.
  • T cells mature in the thymus and are responsible for cell-mediated immunity.
  • Cytotoxic T cells destroy cells that are infected by a pathogen or that are abnormal.
  • Helper T cells assist in activating the production of antibodies by B cells and by stimulating cytotoxic T cells.
  • Antigens are presented to T cells by Major Histocompatibility Complex (MHC) Molecules on the surface of cells.
  • Passive immunity is conferred when an individual is given pre-formed antibodies. Active immunity requires the stimulation of a person's own immune system.

The Immune System

Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.

  • Intro 0:00
  • The Lymphatic System 0:16
    • The Lymphatic System Overview
    • Function 1
    • Function 2
  • Barrier Defenses 3:41
    • Nonspecific vs. Specific Immune Defenses
    • Barrier Defenses
  • Nonspecific Cellular Defenses 7:50
    • Nonspecific Cellular Defenses Overview
    • Phagocytes
    • Neutrophils
    • Macrophages
    • Natural Killer Cells
    • Inflammatory Response
    • Complement
    • Interferons
  • Specific Defenses - Acquired Immunity 20:12
    • T lymphocytes and B lymphocytes
  • B Cells 23:35
    • B Cells & Humoral Immunity
  • Clonal Selection 29:50
    • Clonal Selection
    • Primary Immune Response
    • Secondary Immune Response
    • Cytotoxic T Cells
    • Helper T Cells
  • Major Histocompatibility Complex Molecules 40:44
    • Major Histocompatibility Complex Molecules
  • Helper T Cells 52:36
    • Helper T Cells
  • Mechanisms of Antibody Action 59:00
    • Mechanisms of Antibody Action
    • Opsonization
    • Complement System
  • Classes of Antibodies 1:02:45
    • IgM
    • IgA
    • IgG
    • IgE
  • Passive and Active Immunity 1:05:00
    • Passive Immunity
    • Active Immunity
  • Recognition of Self and Non-Self 1:09:32
    • Recognition of Self and Non-Self
    • Self-Tolerance & Autoimmune Diseases
  • Immunodeficiency 1:13:27
    • Immunodeficiency
    • Chemotherapy
    • AID
  • Example 1: Match the Following Terms with their Descriptions 1:15:26
  • Example 2: Three Components of Non-specific Immunity 1:17:59
  • Example 3: Immunodeficient 1:21:19
  • Example 4: Self-tolerance and Autoimmune Diseases 1:23:07

Transcription: The Immune System

Welcome to Educator.com.0000

Today, we will be focusing on the immune system.0002

And the immune system protects an organism from viruses, bacteria, pathogenic protists, chemicals and even cancer.0005

We will begin by talking about the lymphatic system and then, going to specific cells and proteins that are part of the immune system.0018

The lymphatic system is a network of vessels much like blood vessels in the circulatory system.0027

But, it is actually a separate network that does link up to the main circulation, and it is a network of vessels that contain lymphatic fluid or lymph fluid.0033

Lymph fluid is formed from interstitial fluid.0044

So, interstitial fluid, recall, is fluid that is outside the vessel spaces, so it is outside the blood vessel in the tissue spaces of the body.0050

And lymph fluid is derived from that.0066

In addition to the vessels and lymphatic fluid, lymph nodes, the spleen, the thymus, the adenoids and the tonsils are all part of the lymphatic system.0070

The functions of the lymphatic system are twofold. The first function is for the lymphatic system to return interstitial fluid to the circulation.0084

So, interstitial fluid ends up in the lymphatic vessels, and eventually, the lymphatics meet up with venous circulation in the upper body near the neck.0104

So, then, the lymph fluid, which is derived from interstitial fluid, ends up back in the circulation.0114

In fact, if there is a problem with the lymphatic system, there is a blockage, or sometimes lymph nodes need to be removed, like if a person has cancer,0121

that can cause edema or swelling, which is caused by fluid in the tissue spaces.0129

So, if there is a problem with the lymphatics, let's say under the arm, in the armpit, there are lymph nodes,0134

if some of those are removed, the result can be that the person's arms swells up because there is fluid that cannot be drained.0139

The second function of the lymphatic system is the one we are going to focus on right now.0148

And that is, it functions as part of the immune system. It functions in immunity.0153

Lymph nodes and other lymph tissues contain cells called lymphocytes, and lymphocytes are extremely important in the immune system.0159

Lymphocytes are found in lymph tissue.0172

So, your lymph nodes in your neck, you might find that if you get sick, if you get an infection that involves your head or neck, your throat hurts.0177

Or you get a cut on your face that is infected, that the nodes in your neck become swollen.0186

And that is because the lymph nodes are doing their job where they are scanning that lymphatic fluid that comes through.0193

And if they find an invader, they find a pathogen, they are going to react to it, and they will swell up.0199

So, they function in immune surveillance and in immunity.0206

Now, this is just to give you an overview of what the lymphatic system is, but we are going to talk about many other components of the immune system.0211

And we are going to start with the most general and what is the first line of defense, so I am going to talk about three lines of defense.0218

And the first line would be to keep the invader out, keep the bacteria or the virus or even the chemical out of the body.0226

Before I talk about barrier defenses, I want you to know that there are two broad categories of immune defenses: non-specific and specific.0237

Non-specific includes barrier defenses. These are the first line of defense.0254

There are also non-specific cellular defenses and proteins that function in defense.0261

These are the second line of defense, and then, specific defenses constitute the third line of defense. These are T and B cells.0272

So, non-specific defenses, as the name suggests, do not just target a single type of virus or single type of bacteria.0280

They either target any type of invader, like the skin keeps out...0288

It does not check and see is there a virus or a bacteria or a dust particle. It keeps it all out- non-specific.0293

Even cellular defenses that target many, many types of bacteria or many types of viruses are considered non-specific.0300

Specific means it is really only targeting a very, very particular organism.0308

OK, so, three layers of defense, the first line of defense is barrier to entry.0312

The obvious one is the skin, which is a barrier to entry. It keeps out infectious agents, chemicals, viruses, bacteria, all of that.0321

However, there are other aspects of barrier defense. One is the mucus membrane.0333

Mucus membranes line the tubes in the body that are open to the outside. Remember that the respiratory tract is lined by mucus membranes.0338

The gastrointestinal tract is lined by mucus membrane, the reproductive tract, and these all open to the outside.0351

Looking, for example, at the respiratory tract to give you an example, we breathe in particles.0360

And they make it past the filtration in the nose, and they get into the airway.0370

These particles like dust can become trapped in the mucus that lines the airway.0374

And then, cilia will sweep that mucus up and out, so the particles are expelled out.0380

So, mucus membranes are important in blocking entry of particles into the body.0387

Some other barriers to entry are things like tears. Tears wash pathogens out of the eyes.0397

So if you get dust in your eyes, your eyes will tear up. They will water, and they will flush out whatever is trying to get in.0406

Enzymes called lysozymes are present in the saliva, in the mucus and in the tears.0415

And they are hydrolytic enzymes, so they can break down things like bacteria.0426

pH also plays the function in barrier defense as the acidic environment in the stomach and in the urine kill bacteria that end up in those areas.0433

There is also a fairly low pH. Sweat has a fairly low pH.0454

So, the skin, it keeps the pH on the skin lower, so that also helps to kill bacteria or pathogens that land on the skin.0460

Alright, so, this is the first line of defense- barrier.0471

So, a pathogen - I have been using that word - is a disease-causing organism.0476

Let's say that the pathogen gets past the barrier. It gets into the body.0480

It is going to come into contact with the second line of defense, and these are also non-specific.0486

It is a bit of a misnomer, though, because non-specific cellular defenses do have some discretion.0493

For example, they might target bacteria, not just a particular super specific strain.0500

They might target something on a bacterial cell that many, many bacteria have.0507

But, they are non-specific compared to what we are going to talk about in a few minutes with the T and B cells.0512

So, this is sometimes also called...the barrier and the cellular defenses, the non-specific defenses are also sometimes known as innate defenses.0520

They are there. They are ready to go.0530

They are fast acting versus the other name for specific defenses is acquired defenses or acquired immunity, the Innate immunity.0532

And let's use the word immunity and acquired immunity.0543

So here, we are talking about innate. It is sitting there.0549

It is ready to go, and because non-specific defenses do not have to recognize a very specific organism, they can respond quickly.0552

They do not have to wait to be activated. They just respond.0566

A very important component of non-specific defenses are the cellular defenses.0569

Phagocytes are cells that can engulf and destroy invaders such as bacteria, other microbes, viruses.0577

So, what they do is they engulf pathogens. They engulf other substances as well, but I am going to focus on pathogens.0590

They engulf pathogens, and then, the pathogen is in a vacuole; and the vacuole that whatever these cells engulf,0602

so the cells...here are some bacteria floating around, they are engulfed by the cell, and they end up inside the cell in a vacuole.0613

The vacuole will fuse with the lysosome, and remember from the lecture on cell structure and subcellular structure that lysosomes contain lysozymes.0622

And inside, now, the vacuole has fused with this lysosome, and you end up with these, the lysozymes in here.0635

The lysozymes inside the lysosome can, then, cut up that bacteria, hydrolyze it.0651

So, phagocytes engulf pathogens. They contain them in a vacuole that fuses with the lysosome.0662

Lysozymes inside the lysosome destroy the microbe.0669

Talking about particular types of phagocytic cells, some types of leukocytes or white blood cells are phagocytic cells,0674

specifically, neutrophils, macrophages and natural killer cells- these are often called NK cells.0686

Neutrophils respond to chemical signals that are released by infected cells.0705

If a cell has been infected, let's say a bacterium releases chemical attractants,0713

and the chemical attractants cause the neutrophils to go to the area where the infected cell is; and it will ingest the microbes at that site.0728

Macrophages are derived from a type of white blood cell called a monocyte.0736

They patrol the body and ingest bacteria and other pathogens. So, one of their functions is that they go around and patrol the body.0743

Others are just stationed in a certain area. For example they are also located in the lymph nodes.0752

So, I mentioned lymph fluid is going to go past the lymph nodes.0762

If there is some problem in there, there is a bacterium, then, the macrophage is ready to go ahead and engulf that.0766

Natural killer cells are lymphocytes, so these ones are actually lymphocytes - these two are leukocytes - that recognize infected cells.0776

So, if a cell has been infected by a virus specifically, they will lyse them. They will cause the cell to burst.0802

I just want to clarify, too. All of these are derived from white blood cells.0820

So, they are all leukocytes, but natural killer cells are derived specifically from lymphocytes. OK, they are a type of lymphocyte.0827

Now, we have talked about phagocytic cells and the cellular part of non-specific defense.0843

There are other aspects to non-specific defense that rely very heavily on proteins.0854

First, I am going to talk about the inflammatory response. The inflammatory response does involve cells but involves some important proteins, as well.0862

In the inflammatory response, when inflammation occurs, histamine is released, and mast cells release histamine.0869

The effects of histamine are that it causes blood vessels to dilate and become more permeable, so, I am going to put "they become leaky".0882

They become more permeable.0897

As a result, fluid leaves the blood vessels. Fluid enters the tissue space.0899

So, let's say you have a cut, so you have this cut here in your hand; and what is going to happen is organisms and pathogens0911

could come into the body as a result of that cut, and then, the mast cells will release histamine, and let's say that this is a blood vessel.0925

Let's say this is your skin here, and you got a cut; and now, these mast cells are going to cause a release of histamine.0934

It is going to act on the blood vessels, and there are these red blood cells going through, and there is fluid.0941

And fluid is going to leave the vessels and going to the tissue space, which is one of the reasons why when there is an infection, an area swells up.0945

Now, why is fluid even coming out? How is this helping the situation?0955

Well, this fluid actually contains molecules that attract phagocytes to the area.0960

So, histamine is released at the area where there has been a problem, where there is a possible infection.0969

The blood vessels dilate. They become leaky.0976

Fluid leaves the vessels, goes into the tissue space, and this fluid contains molecules that attract phagocytic cells.0979

Therefore, if a bunch of bacteria has gotten in through this cut, now, neutrophils and macrophages will come to the area and clean it up.0997

Symptoms of infection are attributable to this inflammatory response.1007

Everyone has had an infection, some kind, and since blood flow to an area that is infected increases, what happens is the area swells up.1013

And then, because of this fluid coming out, the area also becomes red and warm.1024

In fact, pyrogens can be released. So, pyrogens are released by macrophages, and they increase the temperature.1030

So, you might get a fever when you have an infection.1038

What they actually do is they cause the hypothalamus to reset the body's thermostat, so the body temperature increases.1041

It is not really well-understood how this fights infection, but it is believed that bacterial growth is inhibited somehow by this increased temperature.1051

So, anyways, symptoms of infection are attributable to the inflammatory response.1059

Non-specific cellular defenses include the actions of phagocytic cells.1065

They include the inflammatory response, which ends up in bringing phagocytic cells to an area where there is a problem.1072

Also, there is a couple of other proteins that you should be familiar with, and that is complement and interferons.1079

These are important parts of the non-specific defense system- second line of defense.1090

Complement is a group of proteins. Complement proteins are found in plasma.1098

So, complement proteins are found in plasma, and they can become activated and then, lyse or burst cells.1104

So, if the cell is infected, or some type of cell that has a problem, they can go ahead and lyse it.1113

Interferons are proteins that help protect the body against spread of a virus, a viral infection.1121

If a cell is infected by a virus, it secretes interferons, so let's say this cell has some viruses in it. It is going to secrete interferons.1135

And what these interferons are going to do is they are going to go and tell nearby cells watch out there is an infection around.1147

So, these cells nearby can, then, synthesize substances that will help prevent them from being infected.1158

This limits the spread of infection, and then, another part of the immune system can get rid of this infected cell, as well, to prevent the spread of infection.1167

So, we have covered non-specific defenses, barrier defenses like the skin,1177

cellular defenses such as neutrophils, macrophages, natural killer cells that can engulf viruses, bacteria.1183

We have talk about the inflammatory response, which brings these cells into the area where there is an infection.1193

Finally, we talked about a couple of sets of proteins that function as non-specific methods of defense.1200

The other half of the equation is the specific defenses, and these are also known as acquired immunity.1208

And you will see why they are called acquired immunity because they need to be triggered.1215

They need to recognize a certain pathogen before they really get going.1221

Specific defenses take longer to be activated than non-specific defenses, but they are an extremely powerful and important part of the immune system.1228

These constitute the third line of defense.1237

T lymphocytes or T cells and B lymphocytes constitute the specific defense system or acquired immunity.1243

Lymphocytes are a type of white blood cell, so they are produced in the bone marrow. There are three types of lymphocytes.1253

There are T cells. There are B cells, and there are natural killer cells that we already talked about.1264

So, these natural killer cells, I said, are part of the non-specific defense system or innate immunity.1273

Here, the T and B cells are the other two lymphocytes. They are part of specific immunity or acquired immunity.1281

We are going to go into each of these types in detail, but to just get you started now, B cells are produced in the bone marrow; and they mature there.1295

So, they are produced and mature in the bone marrow.1306

T cells are produced in the marrow, but they mature in an organ called the thymus- produced in the marrow and mature in thymus.1314

T and B cells are capable of recognizing certain antigens.1334

Antigens are molecules that elicit a response by the immune system, so antigens elicit or trigger a response by the immune system.1340

These are often proteins. For example, a protein on the surface of a bacterial cell could be an antigen and not necessarily even the whole protein.1359

It may be just a certain part of the protein. A little structure is part of this protein that is recognized by a T or B cell.1370

Now, what is extremely important is that there are millions of T cells and B cells, and they recognize different antigens.1377

So, one B cell might recognize a certain part of a protein on Streptococcus.1385

And then, there is another B cell that only recognizes a certain part of a protein on staph infection, a certain subtype of staph infection.1393

So, they are very, very specific.1402

But, there are millions of these, which allow our bodies to protect against almost any possible pathogen that is thrown at us.1404

Now, we are going to start with B cells and then, go on talk about T cells and then, put everything together.1415

B actually stands for bursa, and that has to do with the way B cells were discovered.1423

But, what you should really remember when you think of B is bone marrow because these cells are created and mature in the bone marrow.1429

B cells are responsible for humoral immunity, so B cells- humoral immunity.1440

And then, what you need to contrast that with is cell-mediated immunity when we talk about T cells.1447

T cells, we say, it is a cell-mediated response, and when we say humoral immunity, what we really mean is that these cells produce antibodies.1457

Another word for antibodies is immunoglobulins.1469

Now, how do B cells and T cells recognize a particular antigen?1479

I am going to focus on B cells, but a lot of what I am saying, the general concepts hold true for T cells.1487

We have a B cell, and it has a bunch of receptors on it, and T cell also have receptors called T cell receptors.1496

So, I am focusing on B cells. I have a B cell, and right here are the B cell receptors.1503

When these are secreted, they are antibodies. They are antibodies.1510

A B cell that is turned into a plasma cell can secrete antibodies, so they can go out and bind to antigen.1517

Right now, we are going to focus on a B cell that has these receptors attached.1524

Now, here is the structure of the B cell receptor, which could be an antibody if it is secreted.1528

And what you will see here is that it consists of a heavy chain, two heavy chains and two light chains.1535

Within these heavy and light chains, there are regions called constant regions. These are the dark regions here, constant.1544

Right here, it is a light region. I will just put C, C, C and variable regions at the end.1553

Now, if there is a cell that this is attached to, this part of the heavy chain is going to be in the cell membrane.1563

It is a transmembrane region, and as you can imagine, you cannot just have any structure and have it work inside the hydrophobic cell membrane.1570

It has to be a certain structure.1580

So, it is important that this region is constant and has a certain amino acid sequence.1581

Also, there are these disulfide bonds that hold the heavy and light chains together, and these regions need to be constant so that, that bonding occurs.1587

So, we need constant regions where there is this bonding or its transmembrane.1601

On the ends, though, is really important because that is the antigen-binding site.1605

And there are just almost infinite combinations of what the antigen-binding site can be like.1610

The shape of the antigen-binding site differs from T cell to T cell from B cell to B cell.1618

So, one B cell might have an antigen-binding site shaped like this, and then, if an antigen came along that was roundish, it would fit here.1625

There could be some other B cell receptor that has a different shape, and then, this antigen would not bind; but another antigen might bind.1634

This is what is responsible for the huge diversity of the ability of the immune system to recognize the tremendous diversity of antigens.1647

It is because these antigen-binding sites are different on various cells.1658

So, how is this diversity created at the molecular level? Well, it is through gene rearrangement.1663

Gene rearrangement allows for variation in the antigen-binding site.1671

What I want to be clear, though, is that in one B cell or one T cell, the antigen-binding site is going to be the same for every receptor.1688

It is not like this B cell is going to have one receptor with this shape and then,1697

another receptor that is like this and binds with a different antigen and then, another one that is more like this.1702

It does not work that way. All the receptors on that single B cell will focus on one antigen.1707

So, that is because of how the variable regions were arranged on the DNA.1715

They can rearrange, form different combinations in the light chain and then, in the heavy chain.1722

And those two get put together, and it can come up with just all different shapes.1727

Now, another B cell will have rearranged its DNA differently.1731

And then, it might have some antigen-binding sites that look like this, and on that cell, they are all going to have that same shape.1735

So, one B cell is going to have just a certain type of antigen that it binds to.1742

But, if you put all the B cells together, there is a huge repertoire of what antigens can be recognized.1747

Alright, the important message here is that B cells and T cells have receptors on them that allow them to bind to antigens,1759

and that each B or T cell has a slightly different receptor, which allows them to recognize different antigens and put together...1771

There are just many, many, many millions of possibilities for what these cells can bind to so that our bodies can recognize different invaders.1780

Clonal selection describes what occurs when a particular B cell or T cell recognizes an antigen.1792

So, as I said, there are millions of different kind of receptors, all these different B cells and T cells that recognize various antigens.1803

But if there is a certain infection, what we need is to have many, many, many of the B or T cells that recognize that certain infection/pathogen.1812

Let's focus on B cells right now. So, B cells can recognize antigens that are on a cell, and they can also recognize just free antigens.1824

An example would be there is a bacterial cell. Let's say there is a bacterial cell, and it has these certain proteins on the surface.1839

And a B cell can, then, come along and possibly, depending on the shape of its receptor, recognize one of those.1848

Bacteria also secrete toxins. So, the bacterium might secrete some protein shaped like this or like this that a B cell could recognize.1858

So, let's say that this B cell does recognize some antigen that is out there, and it goes along and then, binds to that antigen.1867

What will occur is that the B cell will be stimulated, and it will proliferate. Proliferate meaning it makes many, many copies or clone cells.1879

So, there will be many clones. Each of these clones will have the same antigen receptor.1899

It will also be able to fight this type of bacteria or virus or whatever it is recognizing.1906

So, if a B cell recognizes an antigen out of all the millions of B cells, there are certain ones that will recognize the antigens from a particular infection,1915

those will be able to bind to the antigen, and they will be stimulated to divide, so B cell recognizes antigen. The B cell binds to the antigen.1924

Therefore, that particular B cell will be stimulated, and it will proliferate. By proliferate, I mean that it divides and creates thousands of clones.1950

Since they are clones, they can also fight that bacterial infection or that viral infection.1970

There are two types of cells that are created from the stimulation of that original B cell.1979

One is plasma cells. The other is memory B cells, so memory cells and plasma cells.1989

What plasma cells do is they secrete antibodies.2003

So, they secrete antibodies, which means that now, there is going to be thousands of these plasma cells secreting antibodies that recognize this antigen.2008

And there is always bacteria running around loose in the body. These antibodies will get it.2021

The memory cells like plasma cells, they carry this type of antigen receptors.2025

So, they recognize this particular antigen, but they do not do anything right away.2033

What they do is they stick around for years and even for the rest of a person's life creating what is called immunological memory.2038

Now, these plasma cells have an immediate effect. They are going to go, and they are going to fight this infection.2047

These do not. They are just going to hangout and wait in case that infection occurs again later on.2053

These plasma cells or what plasma cells are is a type of effector cell.2058

So, plasma cells are one type of effector cell. I will talk about other types in a minute.2063

There are two phases or types of immune response.2069

The primary immune response is mediated by effector cells such as plasma cells. In B cells, these are plasma cells.2074

So, if you get sick, if you are exposed to some kind of pathogen, and you get sick, you are going to first have a primary immune response.2094

And B cells that recognize the antigen on that will be stimulated. They will proliferate.2106

They will create these clones, and the plasma cells will secrete antibodies to fight that infection; and then, you will get well, OK.2113

This response peaks about 2 weeks after an infection and then, drops.2123

If you get that same infection later on, let's say you had the chicken pox, and your body responds;2132

and all these B and T cells are activated, and you get over the chicken pox, and then, ten years later, you are around somebody with the chicken pox,2140

you now have memory cells sitting in your body that will recognize the antigens on that chicken pox or varicella virus. It is called the varicella virus.2149

Anyways, memory cells will be sitting there, and they are ready to go. You have already got thousands of these clones that recognize chicken pox.2161

So, things are just sitting there ready to go. This is the secondary immune response.2172

And you see why we call this acquired immunity because it takes this stimulation by a particular antigen, and you need to build up this immunity.2181

The secondary immune response is mediated by memory cells.2188

You are going to be able to respond more quickly and more strongly the second time around.2201

And so, you may not even end up getting the chicken pox the second time, or maybe you will just get a much lighter case.2206

So, this pool of memory cells is what allows for what we call immunological memory.2214

And it is why for certain types of infections, if somebody gets it, they may not get it again.2224

Even for the rest of their lives, these memory cells could hang around.2233

Now, memory cells are the basis of most types of vaccination, and we are going to talk about that later on.2237

But, just keep in mind that you could end up creating memory cells by getting an infection, having a bacteria, virus in your body.2246

It stimulates the production of memory cells.2253

Or you could be vaccinated with an antigen that will cause you to produce2256

memory cells even though you have not gotten sick and actually caught an infection.2262

I want to just briefly address T cells in general before we go on and talk in detail about2273

T cells and how they are stimulated because T cells also undergo clonal selection, as well.2279

As I said, T cells form in the bone marrow and mature in the thymus, and they are responsible for cell-mediated immunity.2286

There are two types of T cells.2300

One type are cytotoxic T cells. These are also called killer T cells.2304

The second type are called helper T cells, and the names really tell you what they do. Cytotoxic T cells destroy cells that are infected or abnormal.2314

If a cell is infected, and then, the cytotoxic T cell recognizes "well, there is something wrong with this cell".2337

It will produce perforin, which creates pores in the cell membrane and causes the cell to lyse, so killer T cells kill infected cell.2347

Helper T cells do not have a direct action in destroying an infected cell or destroying a bacterium or destroying a virus.2360

They have a very, very important indirect action, multiple indirect actions.2368

What they do is that they help to activate. They have a key role in activating cytotoxic T cells and inactivating B cells.2373

So, they help these other parts of the immune system become activated.2388

Now, like B cells, T cells have antigen receptors on their surface. They have a huge variety of types of antigen receptors.2393

And if they come into contact with a particular antigen that they recognize and can bind to, they will be selected.2405

They will undergo proliferation, and many, many clones will be created; but the way in which this occurs is different.2412

So, B cells can go, and they can recognize an antigen that is floating around loose. It is a protein that was secreted.2420

They can recognize an actual bacterial cell with certain cell surface proteins.2427

So, they just go around, and they are directly looking at these antigens. T cells do not do that.2431

In T cells, antigens need to be what we call presented. They need to be shown to the T cell in a very specific way.2435

And this requires what we call the major histocompatibility complex molecules, or frequently, they are just known as MHC molecules.2445

Fundamental point is that T cells only recognize antigens that have been presented to them, shown to them in a certain way.2457

They do not just recognize a bacterial cell floating around or a protein floating around. They have to have the certain structure.2477

Now, what does presentation of an antigen mean?2486

It means that a cell has broken down an antigen, and then, the antigen is bound to a molecule called major histocompatibility complex.2490

The antigen is, then, displayed on the surface of that cell.2505

Now, let's say that this cell has internalized an antigen. It could be a regular body cell that has been infected by a virus.2510

It could be a macrophage that has engulfed bacteria doing its job and then, broken down this bacteria.2521

So, somehow, there ends up being this foreign protein inside this cell.2530

This cell is going to break it down, take little pieces of the antigen and display them on the surface via this MHC.2536

And so, this cell has all these MHC molecules with various antigens displayed so that T cells can go around and check out what the cells are displaying.2548

Now, what is important to realize is that while there is certainly foreign proteins could be displayed, and they can cause a reaction with T cells,2568

some of the proteins that are displayed are body zone proteins.2580

So, if this cell broke down an old structure and a macromolecule, and it broke it down to get rid of it or recycle it,2583

it could display pieces of that on the cell surface.2592

What is going on with this MHC is it is a reflection of what is going on inside the cell.2597

What is going inside the cell is a lot of normal activities, but there could be problems too.2602

Now, if all the cell is doing is just displaying its normal proteins, the T cells are not going to react. They are not going to bind.2607

They will only bind if there is a foreign molecule that they have the right T cell receptor to recognize.2614

To get a little bit deeper into this, there are actually two types of MHC molecules: class I MHC and class II MHC.2629

Almost all body cells...I am just going to put "all body cells have class I".2642

There are a few exemptions like red blood cells do not have MHC class I, but almost every cell in the body has these.2651

So, that allows nearly every body cell to show T cells what is going on.2659

Class II MHC molecules are only found in very specific types of cells, so they are only found on what is called antigen-presenting cells or APCs.2668

Some types of antigen-presenting cells, so antigen-presenting cells examples...these are phagocytic cells.2689

They are macrophages. They are B cells.2697

B cells are actually a type of antigen-presenting cells and so are another type of white blood cell called dendritic cells.2702

So, just starting out with the MHC class I, almost every cell in the body has these.2710

And if a cell in the body gets infected, it ends up with internalizing this bacteria where a piece of a bacteria, it breaks it down.2717

It presents it on the surface, and let's say this is MHC class I.2728

So, along with all of these normal molecules being presented, there is also this antigen, this bacterial or viral or some other type of protein.2736

Or it could even be a protein from the cell that is abnormal.2747

And there is a lot research being done on this, but in general, the immune system is thought to be able to also recognize cancer cells.2754

The immune system recognizes what is a normal body substance, material protein and will not attack that.2765

But, if the structure is wrong, which happens with cancer cells, they produce abnormal proteins sometimes.2772

That may be recognized as an antigen, the same way a pathogen would be.2777

So anyways, regular proteins and body substances are ignored.2781

But, if there is an antigen here, and out of all the millions of T cells, this one recognizes that antigen, it will use its T cell receptor to bind.2786

Now, remember I said there are two types of T cells.2798

Cytotoxic T cells can have antigen presented to them by class I MHC.2804

So, the type of MHC that is found on every body cell is recognized by cytotoxic T cells.2822

Cytotoxic T cells are also called CD8 cells, and this is because of a material that they have on their cell surface called CD8.2832

And CD8, this is going to be the CD8, and this is a cytotoxic T cell.2849

The cytotoxic T cell has CD8, and CD8 can bind class one MHC; so CD8 binds class I MHC. Meanwhile, the antigen receptor binds the antigen.2868

So, what this does is it helps the two cells to stay together. This cell, let's say, has been infected by a bacteria.2894

It is displaying a protein that is foreign to the body.2901

The cytotoxic T cell comes along. It uses the CD8 to help it stay near the cell because the CD8 can bind the class I MCH.2905

The antigen receptor recognizes and binds to the antigen, and after all this, what happens, this cytotoxic T cell is activated.2915

So, in the same way that clonal selection occurs in B cells when they recognize an antigen,2924

clonal selection occurs in T cells when they recognize an antigen.2934

The big difference is that in T cells, these antigens need to be presented by MHC molecules.2939

Now, I have focused here on cytotoxic T cells. What about helper T cells?2946

Helper T cells are a bit different. Helper T cells do not bind MHC class I.2952

They bind MHC class II, bind class II MHC.2971

Helper T cells are also known as CD4 cells, and just how I said that the CD8 can recognize class I MHC, CD4 recognizes class II MHC.2979

Remember that class II MHC is only found on the special antigen-presenting cells.2997

So, if an antigen-presenting cell like a macrophage ingests a foreign molecule and presents it on class II MHC, helper T cells will be activated.3004

Those helper T cells have CD4 on their surface that allows them to associate with the class II MHC.3016

Then, a T cell receptor on a particular T cell can recognize an antigen. That T cell will be stimulated and will make thousands and thousands of clones.3023

So, T cells just like B cells encounter an antigen, antigen plus MHC.3035

A T cell that is specific for that antigen will proliferate just like the B cells do and make thousands and thousands of clones of two categories.3046

B cells have effector cells and memory cells.3062

So, when a B cell is activated, when it is selected, it proliferates and creates plasma cells that secrete antibodies.3068

Those are effector cells and memory B cells.3075

When T cells are activated, they will proliferate and create clone, thousands and thousands of cells. Some of these will be effector T cells.3078

They will be helper T cells that will go out and do their job right away.3091

Or if it is a cytotoxic T cell, they will be cytotoxic T cell effector cells that go out and start lysing sick cells in the body- infected cells.3094

There is also going to be this big pool of memory cells, of memory helper T cells and memory cytotoxic T cells.3105

So, the next time you get an infection, you will have this whole store of helper T cells3113

and cytotoxic T cells and B cells that are all memory cells that are ready to go.3119

OK, so, clonal selection is fundamentally the same, the principle in T and B cell.3125

But, the details differ because T cells must have antigen presented to them.3132

I do want to note that class II can also present two cytotoxic T cells.3137

So, class I and class II can present two cytotoxic, but class II is the only one that can present to helper T cells.3148

Now, I want to focus more on the role of helper T cells. They have their name because of their key function in activating B cells and cytotoxic T cells.3156

So, They help to activate cytotoxic or killer or CD8 all the same T cells and B cells.3168

I say help to activate because just having a helper T cell around is not activated helper T cell is not alone going to activate cytotoxic T cell or B cell.3184

These will still need to recognize a specific antigen to be activated, but the helper T cells play a very important role.3196

So, let's say that a macrophage or other antigen-presenting cell ingests some bacteria and inside, ends up with this bacterial protein.3206

It breaks that down, and then, it eases its class II MHC to present that antigen on its cell surface.3227

Helper T cell comes along that has an antigen receptor, a T cell receptor that recognizes that particular antigen.3239

This helper T cell will then be stimulated, and it will produce some effector T cells; plus it will produce memory T cells.3251

And for simplicity, I just showed the same one continuing.3270

But, it actually could be these effector ones that are, then, going on and stimulating cytotoxic T cells and B cells.3273

So anyways, the helper T cell becomes activated because it recognizes an antigen presented by a class II MHC molecule on an antigen-presenting cell.3280

As a result of that, a couple of things will happen. This APC is going to secrete cytokines.3292

Cytokines are small proteins. These cytokines will, then, stimulate the T cell, the helper T cell.3304

The helper T cell, in turn, will also secrete cytokines, and it is these cytokines that are going to help activate both cytotoxic T cells and B cells.3316

The cytotoxic T cell, in addition to the cytokine stimulation, is going to have to encounter a3340

cell that has been infected and is presenting an antigen that it recognizes for it to bind to.3347

So, there is an antigen. So, here is an infected body cell, infected cell, and it is presenting an antigen here via MHC class I.3360

The T cell receptor on this cytotoxic T cell is able to bind to that antigen.3369

Now, under the influence of cytokines and the stimulation by recognizing that cell, the cytotoxic T cell is going to become activated.3374

It is going to undergo clonal selection. Cytotoxic T cells are going to produce perforin.3384

They are going to, then, be able to kill infected cell. They are going to be able to do their job.3391

Meanwhile, B cells that have been activated also need to encounter antigens that they recognize. They will be activated.3397

They will create plasma cells. Those plasma cells will secrete antibodies, which will attack the antigens.3407

So, the helper T cell is going to play a role in activating both cell-mediated immunity and in the...3413

so, the cell-mediated response by these cytotoxic T cells and the humoral response, the antibody response by B cells.3429

Now, I have simplified this. It is a bit more complex with the B cells because what the B cells end up needing to do3439

is they do not really just get these cytokines that are secreted and float over.3451

They actually need very close interaction with the helper T cells. Remember that B cells are also antigen-presenting cells.3456

So, they have class II MHC on them, and they, therefore, can present a particular antigen and present that antigen to the helper T cell,3464

activating the helper T cell, which will cause cytokine secretion to activate the B cell.3476

The bottom line, though, is that helper T cells secrete cytokines, and they activate both cytotoxic T cells and B cells. They are part of what activates that.3483

So, cytotoxic T cells, cell-mediated immunity, lyse cells. B cells work via humoral immunity.3501

They secrete antibodies. Helper T cells help both of these to function.3511

Clonal selection causes a pool of effector cells to go out and start fighting the infection, T cells, cytotoxic T cell, B cells, right away.3517

That is the primary immune response.3529

Memory T and B cells are there in case the infection recurs later on. That is the secondary immune response.3531

Now, I have talked about how cytotoxic T cells can create pores and cells and lyse these cells, but how do antibodies work?3540

How do they kill microbes? How do they kill pathogens?3550

Well, there are multiple mechanisms. One mechanism is to block the attachment of the pathogen to the host cell.3554

Let's say there is a bacteria, and it has these antigens sticking out; and it has receptors that allow it to bind to the host cell.3563

So, it binds to the host cell and then, infects, so this is a bacterium; and this is a host cell.3579

And what the bacteria wants to do...except the host cell will actually be a lot bigger than the bacteria.3587

But, the idea is that the bacterium uses some type of receptor to possibly bind to the host cell and infect it.3591

What antibodies can do is they can bind, and they can then block.3602

For example, if this receptor is bound by an antibody, it is not going to be able to bind to the host cell.3611

So, one mechanism of antibody action is binding the surface of the pathogen.3616

The antibodies attach to the surface of the pathogen. Then, the pathogen cannot attach to a host cell.3624

The virus or bacteria cannot attach to the host cell because it is being blocked by antibodies.3631

A second way that antibodies work is called opsonization.3636

In opsonization, antibodies bind to a pathogen. They bind to a microbe, so these antibodies are secreted.3640

They are floating around. They will recognize a virus or bacteria, and they bind to it.3649

Opsonization, what it refers to is that this binding of antibodies to a pathogen facilitates the phagocytosis of a pathogen by macrophage.3654

So, often times, if a microbe has antibodies attached to it, it makes it easier for the macrophage to engulf, recognize and engulf these pathogens.3669

And sometimes the antibodies actually cause the bacteria or viruses to form a big clump, and then, the macrophage just engulfs that whole clump.3681

So, it facilitates...opsonization facilitates phagocytosis of the microbe.3690

So, one mechanism is to block the microbe from attaching to the host cell. Antibodies can do that.3704

A second mechanism is for the antibody to facilitate the phagocytosis of the microbe.3710

A third mechanism that antibodies use is to activate the complement system.3718

What antibodies do is they trigger a series of events that results in the formation of what is called a membrane attack complex.3724

And the membrane attack complex can lyse a cell.3738

So, antibodies trigger the system. The system goes through a bunch of cascade at this whole series of reactions.3743

And then, a membrane attack complex is formed that will lyse the invading cell.3751

So, bacteria or viruses in the body will be either inactivated or eliminated by antibodies.3758

There are actually five classes of antibodies, and they are listed here; so I am going to tell you some major features of each.3766

One thing is that the same cell can produce various types of antibodies but at different times.3774

And each of these has a slightly different structure and role.3780

IgM is usually the first one produced, so it is the first type of antibody that gets secreted in response to an antigen.3783

And these antibodies are slightly different in their structure, OK?3802

So, IgA is found in secreted fluids like saliva, so it is found in saliva.3806

It is found in tears. It is also found in breast milk.3817

And we are going to talk more about the idea of antibodies being in breast milk, for example, and then, being passed on to a newborn.3823

IgG is the most common type of antibody, and it is a type that can cross the placenta; so this protects the fetus.3835

IgE stimulates the release of histamine from mast cells and basophils.3854

Therefore, IgE plays a role in allergies, so if you have, let's say, Hay fever for example.3871

We talked about the inflammatory reaction and how histamine causes blood vessels to dilate and become more permeable.3877

The result is if the blood vessels in your nose dilate and become permeable, you will get a stuffy nose. You will get a runny nose.3884

So, the symptoms of allergies are largely attributable to IgE.3891

I have talked a little bit about immunization, and I want to talk more about it and the concepts of passive and active immunity.3902

I just discussed that IgA is found in milk, so it is found in breast milk.3913

And if a baby nurses, the baby breastfeeds, the baby will ingest antibodies.3920

This is a type of passive immunity. What passive immunity means is that an individual is given preformed antibodies.3926

It is passive because they are being given the antibodies.3936

Their B cells do not need to make those antibodies. They are just accepting the antibodies passively.3939

This confers temporary immunity on the newborn while their immune system is getting and going and developing and getting up to speed.3947

So, it is a temporary measure. It is also very rapid.3957

As soon as you give someone antibodies, they have got that. They are there.3961

They are working. They are preformed.3965

However, it is temporary. In days or weeks or even months when antibodies are broken down and eliminated from the body, that immunity is gone.3967

Another example is IgG crosses the placenta. This is a preformed antibody being given from the mother to the fetus and conferring passive immunity.3979

Sometimes people need some help. They need quick help to fight an infection, and one way is administering immunoglobulins.3995

You might hear about the term immunoglobulin injection or gamma globulin. It is also called gamma globulin.4005

And what this is, is pooled IgG from various people that is given to a person who needs some immune system help.4013

And it is also a form of passive immunity if it is given in this way.4021

So, if you make your own IgA or your own IgG, that is active. You are making it.4026

But if these are given to someone, then, it is passive. If you make your own, it is active.4030

So, a gamma globulin injection, IgG that goes from the mother to the fetus or IgA that is ingested by a newborn via breast milk,4039

these are all passive immunity. It is fast acting, but it is temporary.4048

Active immunity requires the stimulation of a person’s immune system. In active immunity, your own cells are making the antibodies.4054

Your own T cells are killing invaders. Nothing is being given to you.4063

Active immunity can result from stimulation of the immune system by an infection, and it is long lasting.4069

It is mediated by memory cells, so if you acquire an infection, and your body makes memory cells, you may be immune for life to certain infections.4081

So, passive immunity will fight that infection then and there, but it is passive. It is being given to you.4096

Active immunity is your own body reacting, and it is long lasting. An infection can cause active immunity as you fight the infection.4102

Immunizations can cause active immunity, immunization with an antigen. An immunization could contain a killed organism that has antigens on it.4113

But, it will not make a person sick, then, because it is dead or a weakened organism or even recombinant proteins.4127

So, you do not really need to have the whole bacteria/virus to elicit an immune response. You just need that little tiny antigen fragments.4137

So, now, a lot of immunizations are made by just creating recombinant proteins in the lab, and those are enough to elicit an immune response.4142

What an immunization is doing is it is letting your body see what the antigens on a certain bacteria or virus look like.4150

Your body gets ready. It makes all these B cells.4159

It makes these memory T cells, and then, later on, if you are exposed to the infection,4161

you are going to mount a secondary response because your body has already seen the infection.4165

Now, a concept that I mentioned but that we did not delve into is the idea that B cells and T cells recognize foreign antigens.4173

They do not go around, or they should not go around attacking the body's own substances.4183

So, on MHC class I, a cell is showing a T cell. All these different proteins and substances and materials is displaying on its surface.4187

And some of these are the body's own materials, but the T cell does not attack those.4198

B cells do not go around just attacking different body proteins usually. Why is this?4203

Well, during development of lymphocytes, during development of B cells and T cells,4209

those B cells and T cells that have surface receptors against body proteins are eliminated.4216

So, they go through what we sometimes call education, that the T cells and B cells are educated.4225

And what it really is, is that during development, B cells and T cells are shown somehow various proteins and substances and materials from the body.4231

And those that are self-reactive that have receptors that are shaped so that they will bind to the body's own materials, are eliminated.4241

And therefore, once the immune system has matured,4250

the only T cells and B cells that are left are ones that have receptors that will not react and bind to the body’s own structures.4255

What we call this is self-tolerance. T cells, B cells, they tolerate the body's own substances, materials and molecules.4267

They tolerate it. They ignore it.4280

They do not react to it because those cells that would react to it have already been eliminated.4281

Now, autoimmune diseases are a result of failure of self-tolerance.4287

What happens in autoimmune diseases is that T and B cells, the immune system,4294

fails to differentiate self-from non-self, at least with specific proteins, for example, type I diabetes.4304

In type I diabetes, the body ends up attacking cells in the pancreas- the beta cells in the pancreas.4320

Something about those is not realizing "hey, this is self". Instead, it is attacking it, so it is an invader.4333

In multiple sclerosis, the immune system attacks the myelin sheath on neurons. It thinks the myelin sheath is an invader.4340

There are cells in the immune system that bind, attack, activate, and that is going to cause neurological impairments,4352

the impairment of the function of the neurons because that myelin sheath is needed to conduct the signal along the axons.4361

Rheumatoid arthritis, lupus, these are all examples of autoimmune disease.4370

So, it is very important that the body knows self from non-self.4376

The immune system may not recognize a protein on a cancer cell as self because that protein, as I mentioned, may not be shaped normally.4381

There may be something different about it.4391

So, self, it strictly defined, would mean not only it is your own proteins, but is the normal ones.4392

And again, it is not completely well-understood how this all works.4399

But, self versus non-self may also play a role in the immune system protecting us from cancer.4401

Another problem that can occur with the immune system is not attacking oneself but immunodeficiency.4409

This means that an individual's immune function is diminished.4416

We sometimes say the person is immunocompromised, so their immune system is compromised.4422

The result is that the person will be at increased risk of infection. They cannot protect themselves in the usual way.4428

Medications can cause this. A big example is chemotherapy.4436

Some drugs used to treat cancer may suppress the bone marrow. Certain ones suppress the bone marrow.4440

The bone marrow is the site of lymphocyte production, and therefore, a person whose bone marrow is suppressed is at increased risk of infection.4447

There are congenital, so inborn, conditions.4458

Some people have where they are not producing enough lymphocytes. These individuals are immunocompromised.4461

AIDS: AIDS is caused by the human immunodeficiency virus, HIV, and HIV infects helper T cells.4468

Not only does it infect them, it hides within these T cells.4478

As we discussed, helper T cells are needed to activate the immune system, B cells and cytotoxic T cells.4484

So, individuals whose helper T cell count is decreased, they do not have enough helper T cells, are immunocompromised,4492

then, they are more likely to get certain infections.4502

When someone is immunocompromised, even what to us would be a minor infection, can be life threatening.4508

Or organisms that to us may even live in our bodies, they are just, they are there,4515

they do not bother us, could cause serious symptoms in someone who is immunocompromised.4520

Beginning with example one, match the following terms with their descriptions.4528

Cytotoxic T cells: antibody-secreting cells formed from clones of activated B cells.4533

T cells do not secrete antibodies. B cells secrete antibodies, so that is incorrect.4543

Do they recognize and destroy cells infected by pathogens?4548

Well, cytotoxic T cells are also called killer T cells because they kill infected cells, so this is a good answer so far.4554

Display antigens via class II MHC. Include B cells, macrophages and dendritic cells.4563

Cytotoxic T cells are not one of these cell types.4572

They do not use class II to display antigens or secreted by helper T cells, stimulate B cells and cytotoxic T cells. Well, this does not make sense.4576

Cytotoxic T cells are not secreted by helper T cells. In fact, B is correct.4586

Cytotoxic T cells have the job of recognizing and destroying cells that are infected by pathogens.4592

Antigen-presenting cells: are these antibody-secreting cells formed from clones of activated B cells?4600

Do they display antigens via class II MHC? Do they include B cells, macrophages and dendritic cells?4609

Are they secreted by helper T cells, stimulate B cells and cytotoxic T cells?4618

Well, antigen-presenting cells present antigens, and they do it via class II MHC molecules, which are recognized by helper T cells.4625

B cells, macrophages and dendritic cells are all APCs.4635

Finally, we have cytokines and plasma cells.4643

Cytokines do not secrete antibodies. In fact, cytokines are proteins.4647

They are proteins that are secreted by helper T cells among other cell types, and then, they go on; and they stimulate B cells and cytotoxic T cells.4651

The helper T cells secrete cytokines. Those cytokines, then, can stimulate other cell types in the immune system.4662

Finally, plasma cells are antibody-secreting cells that are formed from clones of activated B cells.4670

Example two: list three components of non-specific immunity, and describe their functions.4680

Well, there are many. We could first list some of the barriers, the barrier defenses.4686

So, they asked for three: skin, mucus membranes, tears, saliva, the acid or low pH in the stomach, in urine.4692

These are all components of non-specific immunity, and their function is to prevent entry of pathogens into the body.4712

The second group...so, I asked for three components. You could have gotten three components right here.4728

But, there are many more part of non-specific immunity that also occurs within the body.4734

And components of that are phagocytic cells, for example, neutrophils, macrophages- natural killer cells.4740

The function of these cells is, these are all...actually, let's do this one at a time.4764

Neutrophils are phagocytic cells, and they ingest microbes. They ingest pathogens, so they are phagocytic cells that ingest pathogens.4771

Macrophages: they also ingest pathogens, and a part of their function is to patrol the body looking for pathogens.4785

They are also situated in organs like lymph nodes.4792

Natural killer cells lyse infected cells and cancer cells.4797

Some other components of non-specific immunity are the inflammatory response.4808

The inflammatory response, one major function is to attract phagocytic cells to infection sites.4814

The release of histamine causes permeability of the vessels so that fluid from the vessels ends up in the tissues at the site of an infection.4831

And that attracts neutrophils and macrophages to the area.4839

Complement: that is another part of non-specific immunity, and it is a group of proteins that can lyse cells. The function is to lyse cells.4844

Finally, interferons play a role in protecting cells against viral infection.4854

An infected cell will secrete interferons that will warn nearby cells and prevent the spread of that viral infection.4866

So, these are all...I said list three. There are many more than three that you could have listed.4875

Example three: why might an immunization be less effective in an individual who is immunodeficient?4881

Well, recall that immunization relies upon immunological memory, and it is active.4888

So, active immunity results when a person's immune system is stimulated to produce antibodies.4896

And active immunity or the stimulation of one's immune system also relies on memory cells. Memory cells also result from immune system stimulation.4924

Without the memory cells, immunization will not work. There will not be a pool of cells ready to respond the next time around.4948

If somebody is immunodeficient, what they have is decreased immune function and a decreased number or functioning of T cells and B cells.4956

So, no matter how much you show them the antigen, no matter how much you give them this antigen, try to immunize them,4973

if their T cells and B cells are not going to respond, they are not going to be protected by the immunization.4979

Finally, example four: describe the relationship between self-tolerance and autoimmune diseases.4988

Well, self-tolerance refers to differentiating between self and non-self-molecules, and with cell tolerance, the immune system ignores self molecules.4994

It recognizes this is a normal body molecule and does not attack it.5023

So, an autoimmune disease means that there is a failure of self-recognition, and that the immune system attacks self-molecules.5032

That concludes this discussion of the immune system here at Educator.com.5061

Thank you for visiting.5066

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