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Dr. Carleen Eaton

Dr. Carleen Eaton

Transcription and Translation

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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 (25)

0 answers

Post by Maryam Fayyazi on September 25, 2017

I am a little confused about the TATA box and star codon AUG. Please correct me if I am wrong so the TATA box in on DNA which initiate the transcription but start codon in on mRNA to began the translation

1 answer

Last reply by: Sazzadur Khan
Wed Jan 11, 2017 9:40 PM

Post by Sazzadur Khan on January 11, 2017

during translation, does the process go from E to P to A or from A to P to E?

1 answer

Last reply by: Dr Carleen Eaton
Tue Jun 17, 2014 7:44 PM

Post by Rachel Naiukow on May 31, 2014

Isn't the template strand (in transcription) known as the antisense strand and the coding strand as the sense strand? The sources I looked at said as such. A mnemonic I like to use is that the "sense" strand (makes sense) because it is the same as the mRNA strand being transcribed, with the exception of the Thymine replaced with Uracil. The antisense strand doesn't (make sense) and is complementary.

1 answer

Last reply by: Dr Carleen Eaton
Sun Dec 16, 2012 4:52 PM

Post by omri shick on December 12, 2012

have to thank you!!! you helped me a lot with biology class.

0 answers

Post by Dr Carleen Eaton on November 26, 2012

You are correct. I apologize for the error. For Example III the answer should be:

3'UCG GAA CGC AGU 5'

1 answer

Last reply by: Dr Carleen Eaton
Mon Nov 26, 2012 11:55 PM

Post by jessica chopra on November 21, 2012

at 4:32 you said C and G are purines...thats wrong...A and G are the purines

1 answer

Last reply by: Dr Carleen Eaton
Mon Nov 26, 2012 11:43 PM

Post by bakar yasin on November 14, 2012

Hi. Dr Carleen Eaton,
around 68:55 why does T in DNA becomes U in RNA?

1 answer

Last reply by: Dr Carleen Eaton
Mon Nov 26, 2012 11:44 PM

Post by Chana Heintz on October 21, 2012

in example three the base pairing is done wrong.

1 answer

Last reply by: Dr Carleen Eaton
Mon Nov 26, 2012 11:58 PM

Post by Ikze Cho on October 20, 2012

Dr. Eaton,
isn't the antisense strand complementary to the RNA?

1 answer

Last reply by: Dr Carleen Eaton
Fri Oct 14, 2011 12:20 AM

Post by Daniel Delaney on September 30, 2011

Dr. Eaton,
I can't emphasize enough how simple you made something that was introduced to me as difficult.

1 answer

Last reply by: Dr Carleen Eaton
Sun Jan 9, 2011 11:43 PM

Post by Tomer Eiges on January 8, 2011

This video really helped me, thanks Dr. Eaton

1 answer

Last reply by: Dr Carleen Eaton
Mon Jan 3, 2011 6:39 PM

Post by Samantha Tran on December 30, 2010

In your thrid example, shouldn't the second codon be GAA, not GUU?

2 answers

Last reply by: Loan Doan
Sat Mar 30, 2013 12:51 PM

Post by Dharshini Selladurai on December 7, 2010

purines are A and C Adenine and cytosine.

Transcription and Translation

  • Transcription is initiated when RNA polymerase and transcription factors bind to the promoter region of a gene. The promoter frequently includes the nucleotide sequence TATA and is known as a TATA box.
  • Following transcription, the pre-mRNA undergoes processing to form mRNA. Introns are removed through splicing and a 5' cap and a poly A tail are added to the mRNA.
  • The mRNA is transported out of the nucleus to the cytoplasm where translation takes place.
  • Nucleotide triplets, called codons, signify particular amino acids.
  • The three phases of translation are also initiation, elongation and termination.
  • Translation begins at the start codon AUG, which is also the codon for methionine. Transfer RNA (tRNA) delivers the amino acids to the ribosome to be added to the growing polypeptide chain.
  • Translation is terminated when the ribosome encounters a stop codon.
  • Mutations are changes in the DNA sequence. A change in a single base pair is a point mutations. Types of mutations include silent,missenseand nonsense mutations.
  • Insertions and deletions result in base pairs being added or eliminated from the DNA sequence. This results in a frameshift mutation.

Transcription and Translation

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
  • Transcription and Translation Overview 0:07
    • From DNA to RNA to Protein
  • Structure and Types of RNA 3:14
    • Structure and Types of RNA
    • mRNA
    • rRNA
    • tRNA
  • Transcription 7:54
    • Initiation Phase
    • Elongation Phase
    • Termination Phase
  • RNA Processing 16:11
    • Types of RNA Processing
    • Exons and Introns
    • Splicing & Spliceosomes
    • Addition of a 5' Cap and a Poly A tail
    • Alternative Splicing
  • Translation 23:41
    • Nucleotide Triplets or Codons
    • Start Codon
    • Stop Codons
    • Coding of Amino Acids and Wobble Position
  • Translation Cont. 28:29
    • Transfer RNA (tRNA): Structures and Functions
  • Ribosomes 35:15
    • Peptidyl, Aminoacyl, and Exit Site
  • Steps of Translation 36:58
    • Initiation Phase
    • Elongation Phase
    • Termination Phase
  • Mutations 49:43
    • Types of Mutations
    • Substitutions: Silent
    • Substitutions: Missense
    • Substitutions: Nonsense
    • Insertions and Deletions
  • 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

Transcription: Transcription and Translation

Welcome to Educator.com.0000

We are going to continue our discussion of molecular genetics with the topics of transcription and translation.0002

Before we delve into the details, I am going to give you an overview of the process.0011

Recall that the central dogma of molecular biology is the flow of information from DNA to RNA to protein.0015

The genetic information is contained on DNA.0029

A transcript is made of RNA and this is then, transported.0033

A particular type of RNA, mRNA is transported into the cytoplasm, where it is translated into polypeptide and forms of protein.0039

This process, therefore, is called transcription.0050

The use of a DNA template to form RNA, and the process of going from RNA using that RNA transcript to form a protein is translation.0055

When a protein is made based on the information contained in DNA, we say that the gene has been expressed.0071

A person might carry a gene for red hair, and that is just the gene.0079

But the actual protein that makes the hair color red, when that is made, we say the gene is expressed. It is expressed in the form of red hair.0086

Now, looking at these names, transcription and translation, recall that DNA is made from nucleotides. The nucleotide monomers form a polynucleotide.0095

RNA is also made from nucleotide monomers.0108

There are slight differences between DNA and RNA, but the essential code is the same.0112

Therefore, a DNA template is simply copied. It is transcribed to make the RNA.0117

That is much difference between RNA and protein, so with DNA, you are working with nucleotides, with RNA, with nucleotides.0125

With protein, it is an amino acid sequence.0132

In order to go from this one type of code - nucleotides - to another code - amino acid sequence - is actually translation.0135

You are not just copying something. You are actually taking the information and translating it into a different form.0145

We are going to discuss transcription first, and to understand transcription, you need to have RNA structure down.0154

Again, this is a topic that was covered under the nucleic acid and protein lecture earlier on, but I am going to review the essentials right now.0160

Unlike DNA, RNA molecules are single stranded.0169

Another difference between RNA and DNA is that they contain uracil instead of thymine.0173

The essential structure is the same, though.0180

RNA consists of nucleotides. It is a nucleotide sequence, and looking at what a nucleotide is, there is a pentose sugar; so that is a 5-carbon sugar.0182

In the case of RNA, the sugar is ribose.0194

In DNA, this oxygen is gone. It is deoxygenated.0198

It is deoxyribose, so this is ribonucleic acid.0202

The second element is a nitrogenous base.0206

And recall that there are two sets of nitrogenous bases- the pyrimidines, which contain a 6-membered ring, and they are cytosine, thymine and uracil.0210

In RNA, you will find uracil. In DNA, you will find thymine, and cytosine is found in both.0224

For RNA, we are just going to have C and U.0233

The second type of nitrogenous base is the purines.0236

These contain a 6-membered ring fused to a 5-membered ring and consist of G and C, adenine and - excuse me - guanine and cytosine, so C, U, G, C.0243

The other thing to be aware of besides the differences between RNA and DNA is the types of RNA.0267

There are multiple types of RNA. Three main ones we will be focusing on.0275

One is messenger RNA. The other is ribosomal RNA, and the third is transfer or tRNA.0279

Messenger RNA is the type of RNA that is used for translation.0289

It is the transcript to make a protein.0297

Ribosomal RNA is not used to make a protein. The rRNA is itself, the product.0303

Ribosomes are composed largely of ribosomal RNA, so these are component of ribosomes.0309

tRNA or transfer RNA delivers amino acids to the ribosome during translation, and we will be going into detail about all three types of these as we go along.0323

We are going to start out mainly focusing on mRNA. All three of these would be transcribed.0340

DNA would be used as a template to form all three types, but as we talk about transcription, I am going to focus on mRNA.0345

And then, we are going to follow that process of transcription with translation.0352

Transcription is the process through which RNA is synthesized using a DNA molecule as a template.0359

There are three phases. Initiation, elongation and termination are the three phases.0368

We are going to go through each of these phases starting out with initiation.0375

Initiation begins with the binding of RNA polymerase to the promoter region.0379

The region on DNA, where this gets started, is known as promoter.0385

Here, we have the DNA double helix, and you see it is separated out here in order to allow transcription to occur.0392

Transcription for a particular gene occurs using only one of the DNA strands as a template.0401

In this case, here we have DNA, DNA, and then, in brown, it is the RNA; and you can see that this RNA strand is using this DNA as the template.0408

This is the template strand. Another name for template strand, we sometimes call it the sense strand, and the other is the antisense strand.0420

During initiation - I will put this right here - the RNA polymerase binds to the promoter region.0430

Promoter regions are also known as TATA boxes because they have the sequence T-A-T-A.0447

Initially, where this promoter region is, the RNA polymerase binds, is slightly upstream of where the first actual nucleotide will be transcribed.0459

Things start out, RNA polymerase binds to this promoter region, and then, slightly pass that, we will get the actual transcription of RNA.0471

In addition to RNA polymerase, there are other factors that bind to this promoter region.0487

If you take it together, the RNA polymerase plus other proteins known as transcription factors,0493

what you have is something called the transcription initiation complex.0506

And the job of these transcription factors is to help the RNA polymerase bind to the correct region.0516

We have RNA polymerase plus transcription factors. All that binds together to the promoter region to get things started.0525

And it is known as a transcription initiation complex.0531

In eukaryotes, there is actually a different type of RNA polymerase for each of those three types of RNA that I mentioned- tRNA, rRNA and mRNA.0535

We are focusing right now in messenger RNA.0550

The one that is used to transcribe DNA into what will become messenger RNA is known as RNA polymerase II.0551

RNA Pol II transcribes DNA into what is eventually messenger RNA.0559

This has occurred. This binding has occurred.0566

The transcription initiation complex has bound.0569

The next thing that needs to happen is the double helices to unwind.0571

And again, helicases are involved in this unwinding, this separating out so that the RNA can use the template strand.0575

Now, for a particular gene, the same strand is always used as a template.0584

Let's look at this DNA and say that there is a gene here that is being transcribed.0589

Well, that is what is happening, and we see that this is the template strand.0594

There might be another gene over here that needs to be transcribed, and this strand may be the template for that.0599

So, the same template is used for a particular gene, but it might be a different strand that is used for another gene, so that is initiation.0606

The next thing that needs to happen is elongation.0617

The initiation complex has bound. RNA polymerase is ready to go.0619

It is bound to the template strand. These other factors are bound.0623

We found the TATA box. The helix has been separated.0628

What is going to happen is that RNA polymerase is going to proceed in the 5' to 3' direction, just like DNA polymerase.0632

And it is going to form a strand of RNA that is complementary to the template strand.0641

Remember that complementary means that we would have G and C. Those two are complementary.0645

And with DNA, when we would say "OK, A is complementary with T", for RNA we do not have T. We have U.0656

For RNA, it is going to be A, U, G, C as complementary nucleotides.0666

Looking here at what I mean, this is the template strand for this situation.0672

This is the RNA strand. RNA polymerase is going to seed T, and that is going to tell it to add A for the nucleotide in the growing RNA strand.0681

For C, the complementary strand is going to be G. For G on the template, we are going to have C.0692

For A, if this was DNA synthesis, we would have T, but it is not. It is RNA synthesis, so instead, we are going to have U, G, C.0701

A on the DNA gives me U, A, T and so on, and recall that we just produced one strand.0713

We do not need a double helix. RNA is just single-stranded.0725

You will also notice that this is the same sequence almost as the antisense strand.0731

It is complementary to this template strand or sense strand.0736

And it is the same as antisense not a 100% the same because you will see here, I have AA GG CC T.0739

There is no T here. There is U instead, CC and U instead of T and so on.0748

OK, the first step was initiation transcription complex - excuse me - transcription initiation complex bound to the template strand.0756

Now, we have elongation. RNA, polymerase is adding nucleotides one at the time in the 5' to 3' direction.0766

And this is going to go on until a termination sequence is encountered.0774

A typical termination sequence, a common one is A-A-U-A-A-A.0784

RNA polymerase is going along, and then, it encounters a certain sequence on the DNA that is going to be transcribed into this sequence A-A-U-A-A-A.0795

That is the termination sequence.0803

Shortly after that signal, the newly produced RNA is cut free.0805

This newly produced RNA is not mRNA yet. It is actually known as pre-mRNA or sometimes hnRNA, which stands for heterogeneous nuclear RNA.0811

This is the initial transcript produced.0827

Just reviewing, we had initiation. Then, the RNA polymerase is adding nucleotides 5' to 3'.0830

It encounters a certain sequence that when transcribed it forms A-A-U-A-A-A, which is the termination sequence.0836

Shortly after that, the RNA is released from this complex, and it is free.0844

I mentioned that this initial transcript is not messenger RNA.0856

It is not mRNA. It is pre-mRNA.0860

In order to become mRNA, processing needs to occur, and there is several major types of processing.0863

One of them is splicing. The other is the addition of a 5' cap, and the third is the addition of a poly(A) tail.0871

DNA actually contains both coding and noncoding regions.0879

Coding regions can be expressed as a protein, so they can be used as instructions to form a protein.0883

Noncoding regions do not.0891

Let's first look at DNA, and say we have a piece of DNA like this and there is sections that are coding.0895

And there is sections that are noncoding- 1, 2, 3 to add one more.0909

These numbered sections are going to be the coding regions. These are called exons.0922

These sections in between with no number are introns.0928

The coding regions, again, a protein can be formed from those, and one way to remember this is just remember the introns interrupt.0932

They interrupt the coding regions, and the exons are expressed; so remember ex for expressed and/or you can remember interrupt.0940

In the initial transcript, the pre-mRNA, all of these nucleotides are transcribed.0958

We are going to end up with a transcript that has each of these nucleotides represented.0965

Introns, exons, all of it is there so 1, 2, 3 and 4.0972

However, when the ribosome goes to make the protein, it does not need these interrupting regions.0979

In fact, that would disrupt translation, so we need to get rid of these.0987

In order to form actual messenger RNA, these regions are cut out or spliced out, so this is going to be cut out, cut out, cut out.0991

The result is we are going to be left with 1, 2, 3 and 4- just the exons.1004

The introns have been removed, so we spliced those out.1016

This step is splicing, and this step is performed by spliceosomes.1022

Spliceosomes are composed of snRNPs, or they are also called snRNPs plus protein.1032

Now, what are these snRNPs? What does that stand for?1045

What are they made of?1048

Well, sn is small nuclear ribonucleoproteins. That is why it is abbreviated because it is really long.1049

And small nuclear ribonucleoproteins consist of protein plus a special type of RNA called snRNA.1065

snRNA is what is called a ribozyme. This is RNA that acts as an enzyme or it is thought to be.1076

Ribozymes are RNA that acts as an enzyme, and snRNA is believed to be a ribozyme.1095

Ribozymes, RNA that act as an enzyme. It is thought that snRNA is a ribozyme.1106

When snRNA is combined with particular proteins, it is a snRNP.1112

snRNPs plus other proteins form a particular form a spliceosome, and they are responsible for the splicing.1120

In addition to splicing, a couple other changes are made to form mRNA.1125

A 5' cap is added. Let's say this is 5' and this is 3'.1132

This 5' cap is actually a modified guanine molecule that is added to the 5' region, and then, at the other ends, this is a modified guanine for the 5' cap.1137

The poly(A) tail is on the 3'-end. It is just like you would imagine.1156

It is a string of As, and there is a modified guanine here.1161

The purpose of this cap and tail, it is partly to protect the ends. The other purpose is to mark this as mRNA.1167

In the nucleus the pre-mRNA is formed. These modifications occur, and now, it is marked for export from the nucleus.1176

The mRNA is, then, exported form the nucleus.1184

Before we go on and talk about translation, I want to just mention that there is something called alternative splicing.1187

Seeing how this has been spliced - 1, 2, 3 and 4 were spliced together - it is actually possible - let’s say we start out with the same 1, 2, 3, 4 -1195

instead of splicing it like this, it is possible to splice it differently1219

Instead of just taking out the intron, maybe you will cut out number 2.1223

Maybe you will splice that out, and then, what you will end up with is a transcript that contains1228

- and this is would be spliced out because that is an intron - 1, 3 and 4, those exons.1236

And this actually does happen - this type of alternative splicing - quite frequently with the human genome.1248

And what this allows is for a fewer number of genes - less DNA - to be needed to make a huge variety of protein.1255

And a protein like this that contains 1, 3 and 4 is going to be related to this protein, but it is going to be different.1262

Therefore, you can use a series of exons, kind of, mix and match them to create related proteins, and it is a more efficient use of DNA.1268

It could have been spliced with 2, 3 and 4 or just 4 and 1- various different ways for splicing.1277

OK, just to sum up, RNA processing consists of splicing, in which the noncoding regions are removed1284

as well as the addition of a 5- cap and a poly(A) tail to protect the ends and to let the cell know that this is mRNA.1291

Then, it is exported out of the nucleus into the cytoplasm, where translation can occur.1299

During translation, the RNA transcript is used to create a polypeptide. As I said, this occurs in the cytoplasm.1307

Recall that RNA is formed from nucleotides. Proteins are formed from amino acids.1315

How do we get from nucleotides to amino acids? How is that nucleotide sequence interpreted?1322

Well, it is something called codons.1330

Let's look at a particular RNA sequence, and I am going to cluster these in triplets- CUG, GCU, UAC.1335

I am going to cluster them that way, so that it emphasizes the fact that codons are triplets.1347

And reading from the 5' to 3'-end, I would end up with CUG, and that particular triplet specifies leucine. This is saying leucine should be added.1353

When the ribosome encounters this particular triplet, GCU signifies alanine, UAC- tyrosine.1366

This is how RNA - this is mRNA - can be translated into an amino acid sequence.1381

The ribosome is able to, and in the other translation machinery together with the ribosome,1388

are able to interpret a nucleotide sequence and translate it into an amino acid sequence.1393

You certainly do not need to memorize which codons signify particular amino acids. There is just a few things you should know, though.1400

However, AUG has a special job. It is also the start codon.1408

It specifies methionine. Methionine is always the first amino acid added, and AUG is the start codon.1414

There are several other special codons known as stop codons. UAA, UAG and UGA are stop codons.1422

When the ribosome encounters these, it knows translation is complete.1434

The genetic code is what is known as degenerate or redundant. What this means is that an amino acid can be specified by more than one codon.1441

This is best understood for example, so let's look at the codons for arginine.1450

CGA, CGC, CGG and CGU all code for arginine. All of these signify arginine.1455

If the ribosome encounters these, an arginine will be added there.1471

You have probably noticed that the first two - one and two - positions are the same. This third position is different.1476

This third position is known as the wobble position. Then, we will talk more about this in a minute.1484

But for right now, just be aware that the genetic code is redundant.1490

There is more than one codon for a particular amino acid, and it is that third position that changes.1494

Although it is redundant, it is non-ambiguous. There is no confusion about what amino acid to add.1502

When the ribosome gets to CGC, arginine will be added.1509

There is no question of "oh, should a valine be put here or a leucine?". It is very clear.1513

When the ribosome encounters CGG- same thing. Arginine should be added.1518

Looking at a different set of amino acids, let's look at glycine, GGU.1524

Ribosomes sees that it adds glycine- GGC, GGA and GGG. All of these code for glycine.1531

There is no ambiguity. However, there is redundancy.1545

We have more than one codon. It is redundant, not just one codon, one amino acid.1546

It is redundant- non-ambiguous but redundant.1550

We, now, understand how the code in RNA, the nucleotide sequence, is translated by the translation machinery into an amino acid sequence.1558

In order for this to occur, the elements that are required for translation are a messenger RNA transcript,1569

transfer RNA and ribosomes, as well as the amino acids to add.1578

We have got the transcript, got the amino acids, and we have got the machinery to actually carry out the job.1586

The function of tRNA is to deliver the amino acids to the ribosome, and this shows you the structure of transfer RNA.1593

This is a 2-dimensional representation. If you took the 3D, fold it up, tRNA, and flatten it out, you would get the structure.1602

And there is a couple areas on here that you should be familiar with.1610

The 3'- end is the amino acid attachment site.1613

When the tRNA is sitting there with no amino acid attached, we say that it is uncharged.1622

A charged tRNA is covalently bonded to a particular amino acid.1630

A second important site on the tRNA is this sequence, which is called the anticodon- a triplet called the anticodon.1642

This is a 3'-end, and this is the 5'-end; so if you just look at these three, we are going from 3' to 5'.1653

This anticodon can base pair with the complementary sequence on the mRNA, so let's look at mRNA and what sequence would be complementary.1662

A pairs with U. C pairs with G, and A pairs with U.1673

The ribosome is holding an mRNA, and when it gets to this particular codon,1683

the tRNA that is going to be able to pair with it is going to be the one with the anticodon that is complementary.1692

This sequence, this codon, of course, specifies an amino acid.1700

In this case it is cysteine. This is the codon for cysteine.1707

That means that this tRNA is going to be charged with cysteine.1713

If we were talking about arginine, one of the codons is CGC.1719

If there was a CGC down here, where the anticodon for that,1723

if we got a CGC here and the anticodon to compare with that, this would be holding arginine instead.1729

So, the anticodon pairs up with the codon, and whatever that codon specifies is what that type of tRNA is going to be carrying that amino acid.1736

That is how the tRNA gets the correct amino acid to the correct place.1746

Obviously, it is very important that there is a charging done correctly.1752

And the job of making sure that the correct amino acid gets bonded to the correct transfer RNA is performed by enzymes called aminoacyl tRNA synthetases.1758

There are twenty of these. There is one for each type of amino acid, and what this type of enzyme does is it holds on to a tRNA.1776

It also holds on to the amino acid that belongs to that tRNA and catalyzes the attachment of, say in this case, cysteine to this tRNA.1785

Once that is charged, it can deliver its amino acid to the ribosome at the correct place.1796

There are actually 61 codons, but they are not 61 tRNAs.1804

There is actually about 40 in bacteria and about 50 in eukaryotes, so I am going to say there is only 40 to 50 tRNAs.1810

How does that work? Each codon does not have a special tRNA.1819

Well, it has to do with the wobble position that we talked about.1827

Let's revisit arginine that we talked about- the codons for arginine: CGA, CGC, CGG and CGU.1830

In this third position, why is it called the wobble?1850

The reason it is called the wobble is there is some flexibility in the binding of the anticodon to the codon in this 5' or wobble position.1855

Focusing on, let’s say we have a tRNA and going from 3', it is GCG.1866

We would expect it to pair up with an mRNA that goes 5' CGC. That is expected.1880

That is typical Watson Crick base pairing rules is G would go with C, and A would go with T; or in RNA, A would go with U.1892

This is what I expect, that when this codon is encountered, tRNA will float in. It will base pair codon, anticodon, and CGC specifies arginine.1903

This tRNA will be holding an arginine, and argentine will get added- fine.1918

However, let's say I had a different codon. I had an mRNA that contained CGU.1922

Actually, this tRNA anticodon can base pair with this codon. GC, expected, CG, expected, GU, that is not expected, but it is allowed.1933

In this wobble position, in this 5' anticodon position, the rules of base pairing are a little bit more flexible.1946

G in the 5' wobble position can pair with C and U.1956

In the wobble position, if there is a U, it is actually allowed to pair with both A and G.1964

You see how you will not need a single tRNA for every codon.1972

Instead, there could be a tRNA with GCG, and it could add an argentine when it comes upon either this CGC codon or the CGU codon.1977

And that is because of that wobble position.1991

tRNA is one component needed for translation as well as mRNA and, of course, the amino acids.1994

The other very important component is ribosomes, and we talked about this briefly when we talked about cell structure but now delving into more detail.2002

To understand translation, you need to understand various parts of the ribosome.2010

Ribosomes consist of a large subunit, a small subunit and ribosomal RNA.2014

They contain some particular binding sites.2022

Here is the mRNA, so there is a site for the mRNA to attach.2026

There is also several places where tRNA can be located.2030

These three sites are the E-site, which is the exit site. That is a channel that the tRNA can leave through.2035

The A-site which is known as the aminoacyl site.2043

In that site, you would find tRNA attached to an amino acid, the incoming tRNA carrying the next amino acid to be added.2048

The P-site is the peptidyl site. What you would find in that site is the tRNA carrying the growing peptide chain.2058

There will be a tRNA in here, and it is going to have this peptide chain attached.2070

And then, another tRNA will come in carrying the next amino acid to be added.2077

And then, eventually the empty tRNA we will see in a second will leave through this exit site.2084

Just be aware that there is a place for the mRNA. There is an exit site, a peptidyl transfer RNA site and an aminoacyl transfer RNA site.2089

Looking at the steps of translation, we talked about transcription. There are three phases.2102

There are three phases here, as well, and they have the same names- initiation, elongation and termination.2108

Starting of course with initiation, during initiation, the two ribosomal subunits, the mRNA and the first tRNA comes together.2116

The components of translation are assembled. They come together.2128

Initially, the two ribosomal subunits are not together. The small subunit binds first, and it binds upstream of the start codon.2140

The small ribosomal subunit binds upstream of the start codon. It binds to the mRNA upstream of the start codon.2151

Remember that the start codon is AUG, and that is also the codon that signifies methionine. In addition...well, it is OK.2166

So, then, right now, we just got this small subunit, and we have got the mRNA.2188

This small subunit actually, then, after it is bound upstream, it moves downstream until it gets to the start codon.2192

It needs to reach that AUG, and at that point, the large subunit will bind.2204

During initiation, the small ribosomal subunit binds first, binds upstream of the start codon. It moves to the start codon.2208

The large subunit binds. The ribosome is assembled.2216

The other thing that comes into play is that first tRNA, and the first tRNA is known as the initiator tRNA.2219

That is what you are seeing here at the beginning of the process, the initiator tRNA.2232

And since the start codon is AUG, this initiator tRNA is going to be charged with or carrying the amino acid methionine.2236

This process is facilitated by initiation factors, and it requires GTP; so initiation requires GTP, and it is facilitated by initiation factors.2245

In addition to the ribosome, the tRNA, amino acids and mRNA, to get things started, other proteins are needed.2261

And GTP will be hydrolyzed to provide energy for the process.2270

Now, I said that the first amino acid, the one at the start codon, is methionine.2275

And this is going to end up being at the N-terminus because amino acids are put together2280

to form a polypeptide starting at the N-terminus and ending at the C-terminus.2287

However, that does not mean that every single protein ends up with a methionine first2291

because sometimes, the methionine is cleaved off later as part of posttranslational processing.2296

During the translation process, yes, methionine will be added first, but it does not necessarily stay there.2302

Alright, initiation occurred. We have got the ribosome, the mRNA.2310

We have got this initiator, tRNA, ready to go with the methionine.2315

Now, notice that this is in the P-site. That very first tRNA starts off in the peptidyl site.2318

During elongation, what is going to happen is amino acids will be added one at a time, and the order of construction is from the N-terminus to the C-terminus.2328

Here, we have our start codon. The start codon is AUG.2342

Recall that the tRNA that is carrying a codon complementary to AUG is going to be able to come in, hydrogen bond temporarily with the codon.2347

So, here we have the codon. Here, we have the anticodon, and it is going to be carrying methionine.2363

Now, let's say this next codon encodes glycine. There is tRNAs floating around.2368

and eventually, the correct tRNA, the one that is carrying the anticodon complementary to the codon, is going to float in to this A-site.2376

And it is going to be able to hydrogen bond with the codon, and it is coding for glycine; and it is going to be carrying a glycine.2387

I have this methionine charged tRNA in the P-site. Now, I have the next one to be added in the A-site, so P-site.2395

And then, the new amino acid to be added goes in the aminoacyl tRNA site.2408

What happens next during elongation is that the ribosome is going to catalyze the formation of the bond between2416

the peptide chain - right now, there is only one amino acid here, but eventually it will be a chain - in the P-site and the amino acid in the A-site.2427

During that process, this chain...right now, just one amino acid will be transferred to the tRNA on the A-site.2436

GTP is also hydrolyzed during this step. GTP is needed for elongation.2449

OK, so, we had an amino acid on this tRNA.2455

We had the incoming amino acid glycine, and now, a bond is going to be hydrolyzed between these two.2460

Now, we have a little polypeptide chain consisting of methionine and glycine. Next is translocation.2466

Elongation is going to consist of growing the polypeptide chain by catalyzing the polypeptide bond.2478

So we add amino acids and translocate the tRNAs to the next site.2491

This is now empty. It needs to just leave.2503

This tRNA is going to be translocated to this exit site, and it is going to leave.2507

It is going to float off, and it is going to pick up the correct amino acid that is floating around in the cytoplasm, be charged.2513

And then, it can go along and add another methionine where it is needed.2519

This empty tRNA goes to the E-site, and then, it leaves.2525

Now, this is no longer just one amino acid by itself. It is now a peptide chain.2528

Therefore, this tRNA is going to be translocated to the P-site.2533

The mRNA is going to be shifted over until this codon is in the A-site.2538

Let's say that this codes for valine. Let's say it is the codon for valine.2546

Then, this will be shifted to the A-site. The tRNA with the anticodon for valine and carrying valine charged with it will float into the A-site.2554

This peptide chain and this tRNA in the P-site, this one is gone. and the process will continue.2563

The essential points are that the incoming tRNA with the correct amino acid floats in and enters the A-site.2568

The ribosome catalyzes the bonding between the peptide chain on the tRNA on the P-site to the new incoming amino acid.2577

The empty tRNA exits through the exit site, and then, everything is pretty much translocated over one.2588

And the mRNA is being moved along by the ribosome 5'-end first. That is elongation.2598

This is going to continue on until the ribosome encounters a stop codon.2606

At that point, termination will occur.2612

So, along goes...the mRNA has been moved along, moved along, moved along, and then, finally, the ribosome encounters a stop codon.2616

Remember UAA, UAG and UGA.2625

If the ribosome encounters that, it does not specify an amino acid, so there is no tRNA that is going to come along and add an amino acid.2630

Instead, what is going to bind is something called a release factor.2638

The release factor is shaped like a tRNA, and it binds, then, at this A-site.2642

Once we get to a stop codon, the release factor will bind, but it does not add an amino acid.2649

Instead, what it does is it hydrolyzes the bond between the peptide and the last tRNA, so the release factor adds water.2654

Normally, elongation is going along. One amino acid is added to the chain and so on, and so on, and it grows.2668

The release factor does not add an amino acid. It adds water.2676

By adding water here, the peptide strand is released. It has let go.2679

It floats away, and then, this complex disassembles.2685

The mRNA goes off. These two subunits disassociate.2689

The tRNAs go off, and then, they can all go be used to make another protein.2693

Three main steps: initiation, elongation and termination, and termination occurs when a stop codon is encountered.2699

A release factor binds, enters that A-site and adds water instead of adding an amino acid.2707

Many ribosomes can actually translate a single mRNA molecule at once.2717

You will have this mRNA going along, and there will be a bunch of ribosomes bound to it at different points, trailing out these polypeptides.2722

And when you see this complex with a bunch of ribosomes on a single mRNA molecule, it is called a polyribosome or sometimes just a polysome.2741

Recall that once this polypeptide chain is made, a lot of times, we just say "oh the protein has been made", but technically, it is not a protein yet.2754

It is only a polypeptide.2763

The primary sequence of a protein is its amino acid sequence, the primary structure, but it will fold into a 3-dimensional shape to actually become a protein.2765

Right now, that initial product, that amino acid sequence, is just a polypeptide chain.2777

It is going to undergo folding, and we talked in an earlier lecture about the different types of folding; and we talked about protein structure.2784

Recall that there is a secondary structure, which involves a hydrogen bonding between different regions within a polypeptide chain.2795

There were alpha-helices and beta-pleated sheets that was within a single polypeptide chain, and then, there is a tertiary structure.2805

And folding occurs so that this polypeptide chain forms an overall 3-dimensional shape.2821

Sometimes the shape is more globular like with hemoglobin. The shape can also be fibrous like with keratin.2827

Finally, some proteins have a quaternary structure when they are composed of multi-polypeptide chains.2834

Again, if you need to review that, look back in the lecture on proteins and nucleic acids.2842

Finally, some posttranslational modifications may need to occur like the addition of phosphate groups, the cleavage of the sequences.2847

And at that point, you have the final product.2854

You have the polypeptide chain. It is folded up.2856

It had modifications, things added, things removed, and now you have the product.2859

Mutations are changes in DNA sequence, and this was mentioned briefly earlier on when we talked about DNA synthesis.2867

But we want to talk about the implications of mutations on protein structure.2874

Now, initially, maybe DNA polymerase adds the wrong nucleotide, but often, it catches that mistake; or that mistake is repaired quickly by mismatch repair.2881

If it is not repaired and it creates a permanent change in a base pair, then there is mutation.2891

And these mutations are going to be passed along to the daughter cells.2897

Whenever that cell replicates its DNA, and then, the cell divides, that is going to be passed along.2900

If there is a mutation in the cells that will form germ cells, then, that mutation is actually going to be passed along to an organism's offsprings.2907

Point mutations are mutations in a single base pair. They are a change in a single base pair- change in one base pair.2916

There are multiple types of point mutations. They can be substitutions, insertions and deletions.2931

In a substitution, the base pair is changed. It is a different set of nucleotides.2938

However, the number of nucleotides is still the same.2946

Insertions- nucleotides are added. Deletions- they are removed.2950

Let's focus first on substitution mutations. In substitutions, there has been a change to one base pair, but the number is the same.2954

You could have a point mutation that it is a change. It is an adding of a single base pair here.2975

It is just changing the actual nucleotide.2980

For example, looking at DNA, I have got my DNA 5' to 3', and then, I have got the complementary strand.2982

Actually let’s do this slightly differently.2997

Let's say I have DNA 3' TTC to 5', and I am going to have a complementary strand, of course, because it is a double helix.3001

But I am going to focus on this strand, and this, let’s say, is the template strand for a particular gene.3015

When transcription occurs, you are going to end up with an RNA strand that is complementary.3021

T is going to pair up with A. T is going to pair up with A.3027

C is going to signify G.3041

When this is transcribed, the product of transcription, the mRNA is going to be this sequence- AAG.3044

AAG is actually the codon for lysine, so initially, this DNA encoded the information that lysine should go in a particular spot on the protein.3058

Let's say a mutation occurs. This becomes mutated, and you instead end up with DNA template strand 3' TT; but now, the third one is also T.3069

There has been this mutation. C has been changed.3090

There is a change in the DNA sequence. C is changed to T.3094

Now, when RNA polymerase comes along, and it sees this sequence,3098

it is going to say "OK, I need to add a T - excuse me - an A. I need to add an A. I need to add another A".3103

Normally, a G would be added here. Instead, an A was added.3114

There has been a change in DNA sequence. There is a few possible outcomes.3120

As it turns out, it is pretty lucky that the change was here in this third spot because remember that the genetic code is redundant,3124

that there is more than one codon for a particular amino acid.3134

And as it happens, AAG codes for lysine, and AAA codes for lysine.3137

That third position, that wobble position, often if you change that, you get the same amino acid.3143

When the ribosome comes along, and it sees this, it is going to add lysine. If it came along and saw this instead, it is going to add lysine.3150

There is going to be no effect on the protein. The protein is going to be completely normal because the lysine went where it should be.3162

This type of mutation is called a silent mutation, so for substitutions, there are three kinds of substitutions.3168

The first kind, the result is a silent mutation. There has been no change in the amino acid that is specified.3181

When you look at the protein that resulted, it is the same. There has been no change in the amino acid sequence.3193

That is the best case because, then, there is no problem with the protein. The protein will still function correctly.3199

This mutation is silent. It is not expressed in the phenotype.3205

It is there, but it is quiet.3209

The second type of mutation is known as a missense mutation. Let's look at an example.3211

This was first. We had silent, now, missense.3219

Let's say that I have this DNA template strand, and the 3' is GAA and then, 5'-end here.3229

And it would result in a transcribed mRNA that looks like this: 5' CUU to 3'.3238

This is actually a codon for leucine, and let's say a mutation occurs; and we end up with 3' G, but instead of A, we get a T.3251

RNA polymerase comes along and makes an mRNA based on this, and it is going to be 5' C. T is going to specify A, and the A is going to specify U.3270

There has been a change here. There is a change from G to A up here, but it did not really matter because these both coded for lysine.3287

However, CAU does not code for leucine. It actually codes for histidine.3294

There has been an impact then. A different amino acid will be added.3303

If I took this DNA and watch it be transcribed and translated, I would see a protein with a leucine in a certain spot.3307

This DNA used to form this mRNA is going to give a protein with histidine.3314

If there is a change to a different amino acid, that is a missense mutation. There has been a change in one amino acid.3319

Sometimes it is not a big deal.3333

Maybe those two amino acids are similar like they are both hydrophobic, or they are both basic.3335

And maybe they are located outside the active site of an enzyme, or they do not make a big difference in the folding of the protein in the structure.3342

Sometimes, it will not be a major deal. Other times it is.3348

Sickle-cell anemia is a disease that is actually caused by a change in only one amino acid.3353

In sickle-cell anemia, there is a change from glutamic acid to valine. That single change causes a difference in hemoglobin structure.3360

The hemoglobin is abnormal, and hemoglobin is found in red blood cells. It carries oxygen.3376

Under conditions of low oxygen, that hemoglobin causes the red blood cell to be shaped abnormally.3381

It actually causes it to, kind of, flatten out the shape, which is a shape of a sickle, hence the name sickle-cell anemia.3388

The problem is when cells sickle like that, they clump up. They block the smaller blood vessels.3397

And they can cause organs and tissues not to get enough oxygen, which is painful and can actually damage organs and tissues.3403

There are profound effects sometimes from a change of a single amino acid.3411

The other thing to think about is that mutations account for genetic diversity. Often times, these mutations are deleterious.3415

They will cause the protein not to work as well. They will cause the organism not to be as healthy, perhaps.3425

However, sometimes, the protein may function better, or under certain conditions, it is favorable to have that mutation.3432

And when talk about evolution, we will see how the genetic diversity and selection pressure for a particular phenotypes and traits works.3440

So one source of genetic diversity is mutations.3451

We talked about silent and missense mutations. Finally, the third type of substitution mutation is a nonsense mutation.3457

Nonsense mutations result in the change from an amino acid to a stop codon.3467

Perhaps, the DNA template was a CG on the DNA, which codes for cysteine, and we get our mRNA UGC.3478

We end up with cysteine added. Then, there is a mutation.3499

Now, we have DNA that is A, C and then T, so there has been a mutation.3503

This mRNA is, then, going to give me UGA. That is one of the stop codons.3518

Silent mutation- no effect on the amino acid. Missense mutation- a single change in an amino acid.3529

Nonsense mutation is a change from an amino acid to a stop codon,3536

which means that the protein is going to be shorter than it should be and generally, non-functional3540

unless you get very lucky, and this occurred way, way, way at the end. Usually though, this is a major effect.3546

Now, we talked about substitutions, where there has been a change in the amino acid sequence.3554

But another possibility is that amino acids have been - excuse me - nucleotides have been added or removed.3562

These are known as insertions and deletions.3577

Let's say that I have DNA looks like this: AGC, TCA, CTT.3583

Well, there is what is called a reading frame.3601

If you are reading in a book, and you are reading, say, a simple sentence "The boy can see.".3604

The reason this makes sense is you know where to start. You start over here on the left, and you know how to group these, the reading frame.3619

This is a word. This is a word.3625

This is a word. This is a word.3627

The ribosome reads as the same way. This is a codon, codon, codon.3628

If I stuck a letter in here, let's say I put an A right in here, now, the reading frame would be changed if I was reading every 3 it would be TA, EBO, YCA.3633

It would not make sense if I try to group those into words. The same thing can happen here.3651

If there is a mutation, and let’s say we add a T right here, so then, this might have signified just say lysine, valine, histidine.3655

Now, instead of AGC, I have AGT. Let me see.3672

Oh, actually, we need to change that. I will left out the C.3681

Let me change that. If I add a T here, and then, I would have my C still, I would have C, TCA, CTT.3688

There we go. Now that is added.3703

I have, instead of AGC, I have AGT. The C is still there, but now, it is part of the CTC as a codon instead of TCA.3704

Then, I have ACT and so on.3717

The protein from that point downstream is going to be messed up3720

because these amino acids are completely different than the amino acids that should have been specified.3725

And in fact, what often happens in this case, is one of these ends up being a stop codon.3731

So then, the protein is just truncated, so if within insertion or a deletion.3737

If I added an amino acid or excuse me, a nucleotide, if I added a nucleotide or took one out, either way, that would change what is called the reading frame.3743

And when the reading frame is changed, it is known as a frameshift mutation.3760

Adding or deleting insertions or deletions can result in frameshift, and that is a very severe mutation.3766

It could be just a point mutation, where a single base pair is added or a single base pair is removed, or there might be a large segment added or removed.3773

When we talked about chromosomes, we talked a little bit about larger problems that can occur.3783

This is just point mutations, but recall that there could be larger problems.3787

A part of a chromosome could break off, and then, that would be a large deletion. Parts of the chromosomes could be copied- duplications.3792

During miosis, if there is unequal crossing over, you can end up with large segments that are duplicated or large segments that are left out.3801

Mutations can occur spontaneously.3812

DNA polymerase makes a mistake. It is not caught.3816

Mismatch repair does not occur. It just happens sometimes, so these mistakes made during replication that is passed along.3819

Mutations may also be initiated by mutagens.3827

It is not just part of a natural error rate of DNA polymerase, but it is some chemical or physical mechanism that causes damage to the DNA.3830

Mutagens can be chemical. Certain chemicals are known as mutagens, or they can be physical.3839

Physical factors such as excessive exposure to sunlight can be a mutagen. X-rays can be a mutagen.3854

This, then, can result in a change in the DNA sequence, and such changes can actually result in cancer sometimes.3862

And therefore, we also say that certain mutagens or many mutagens are carcinogens.3872

Excessive exposure to a certain chemical can cause a change in the DNA sequence that may cause cancer.3878

We would say that that chemical is carcinogenic. It is mutagenic, and it is carcinogenic.3884

Alright, today, we covered quite a bit. We covered transcription, translation and mutations.3890

Now, we are going to review these concepts.3895

Example one: list three types of processing that are performed on pre-mRNA.3898

Recall that the immediate product of transcription is not mRNA. It is pre-mRNA.3906

In order to form mRNA, processing needs to be done.3913

Three major types are splicing, splicing is the process of removing introns, and they are fusing together the coding regions of DNA- the exons.3918

A second type of processing that occurs is the addition of the 5'- cap. This is a modified guanine nucleotide.3936

There is also the addition of a series of adenines that is the 3' poly(A) tail.3949

And the 5' cap and poly(A) tail protect the ends of the mRNA and signify that it is mRNA destined for export from the nucleus.3958

So, these are three types of processing that occur.3966

The terms below are related to the process of translation. Match each one to its description.3972

First we have elongation- delivers amino acids to the ribosome- that is not elongation.3978

A phase during which amino acids are added to the growing polypeptide chain- that is actually correct.3987

Remember that there are three phases of translation: initiation, elongation and termination.3997

Elongation is the phase during which the amino acids are added.4005

Alright, next, tRNA- delivers amino acids to the ribosome.4010

Well, that is already the correct one. That is the function of tRNA.4018

tRNA is charged with a particular amino acid.4024

When that tRNA encounters the codon that is complementary to its anticodon, it can base pair and it is carrying that amino acid.4027

That amino acid will be added to the growing polypeptide chain by the ribosome.4035

P-site - alright, we already used up A and B - it hydrolyzes the bond between the polypeptide chain and the tRNA once translation is completed.4040

Well, the P-site is just a site. It does not hydrolyze something.4051

D: sequence on tRNA that base pairs to a complementary codon on mRNA.4057

The P-site is not a sequence on the mRNA. Site of the ribosome, where the tRNA bound to the polypeptide is located.4063

This is a site on the ribosome, and E is the correct answer.4073

The P-site is the peptidyl site. It is the site where the tRNA carrying the polypeptide chain is located.4079

Anticodon: we used up E, and we already mentioned that this is a sequence; and that is what an anticodon is.4087

It is a triplet sequence, and it is found on tRNA; and it is going to be complementary to a particular codon on mRNA, so that is D.4098

That leaves us with release factor, which must be C.4110

And does the release factor hydrolyze the bond between the polypeptide chain and the tRNA once translation is competed? Yes.4115

When the ribosome encounters a stop codon, instead of a tRNA entering the A-site,4121

a release factor will enter the release site and add water to the polypeptide chain.4127

The polypeptide chain will be freed from the tRNA it is attached to.4132

Example three: the template strand used for transcription of a gene is shown below.4139

What would the RNA sequence of the transcript be?4144

Note always that you have to pay attention to directionality.4150

Here we have a template strand, so this is DNA; and what this question is asking me is what is the complementary RNA sequence going to be.4154

When you approach these, think about the directionality because sometimes wrong answers will have 5' here and 3' here or something.4162

Make sure that you first write in the directionality- 3' and 5'.4170

Using base pairing rules, I know that A is going to pair with U for RNA. There is no T.4178

That is another mistake that gets made is people put T here.4185

G pairs with C so AT, GC for DNA. For RNA, it is going to be AU, GC.4189

C pairs with G. C specifies G for complementary.4204

T gives us the U. The complementary nucleotide, the T is a U, GC, CG, GC, UGU.4210

This is a sequence that would be found in the transcript. This would be the template strand.4224

And then, the other strand on DNA, the antisense strand, would have this sequence except that the Us would be replaced with Ts.4232

Describe the three types of substitution mutations that can occur. Substitution means that there is a change in a single base pair.4243

And there are three possible types of substitutions: silent mutations, missense mutations and nonsense mutations.4251

In silent mutations, the result is another codon that specifies the same amino acid.4265

Although the DNA sequence is changed by look, it is changed to a sequence that specifies for a codon for the same amino acid as the original sequence.4282

A missense mutation- change to a codon for a different amino acid.4294

A change has occurred in the DNA sequence, and it is going to result in a codon that for example instead of specifying for valine, it specifies for glycine.4307

There is going to be a single amino acid change in that protein.4317

Nonsense mutation is change to a stop codon, initially, a DNA sequence coded for an amino acid.4320

The codon was for an amino acid. Its change in sequence results in a stop codon in that place.4332

So, these are the three types of substitution mutations.4339

That concludes this lesson on transcription and translation.4343

Thanks for visiting Educator.com.4347

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