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Dr. Carleen Eaton

Dr. Carleen Eaton

Meiosis

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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 (10)

1 answer

Last reply by: Dr Carleen Eaton
Wed Mar 26, 2014 6:57 PM

Post by Muhammad Ziad on January 12, 2014

Hi Dr. Eaton,
At 50:20, I'm a little confused on how you got the number of chromosomes for the zygote. Didn't you say previously that the zygote will have 46 chromosomes, 2n, diploid?

1 answer

Last reply by: Dr Carleen Eaton
Wed Mar 26, 2014 6:46 PM

Post by Brian Bartley on January 12, 2014

Dr. Eaton,
Is it accurate to say there is 4n DNA while chromosomes are 2n at Meiosis Prophase I or at Mitosis Prophase?

1 answer

Last reply by: Dr Carleen Eaton
Tue Sep 11, 2012 3:44 PM

Post by Nitin Pothen on September 10, 2012

so in Telophase 1 is the Haploid state formation ,not before that right ?

1 answer

Last reply by: Dr Carleen Eaton
Mon Nov 14, 2011 10:17 PM

Post by felix michoutchenko on November 5, 2011

If you look at a sperm cell or an egg cell via a microscope, would you see a single stranded chromosome or double stranded (replicated) chromosome?

Also, can nonsister chromatids exchange whole arms (q or p arms) or do they only exchange the tips of the arms??


Thank you in advance.

I wasn't able to find this info on the net.

1 answer

Last reply by: Dr Carleen Eaton
Fri Oct 14, 2011 12:18 AM

Post by luna sahle on September 28, 2011

Is it possible for some of the gametes to have just paternal or maternal genes?

Meiosis

  • Meiosis results in daughter cells that are not identical and contain only half the number of chromosomes found in the parent cell.
  • Diploid cells have two sets of chromosomes. Somatic cells are diploid. Gametes are produced via meiosis and are haploid; they contain only one set of chromosomes.
  • Meiosis involves two rounds of cell division, meiosis I and meiosis II. Meoisis I is the reductive division.
  • During prophase I homologous chromosomes pair up in a process called synapsis. Crossing over is the exchange of DNA between homologous chromosomes.
  • Homologous pairs of chromosomes line up along the metaphase plate during metaphase I.
  • Homologs separate and move to opposite poles of the cell during anaphase I.
  • Meiosis II is similar to mitosis. It consists of prophase II, metaphase II, anaphase II and telophase II. In anaphase II, sister chromatids separate and move to opposite poles.

Meiosis

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
  • Haploid and Diploid Cells 0:09
    • Diploid and Somatic Cells
    • Haploid and Gametes
    • Example: Human Cells and Chromosomes
    • Sex Chromosomes
  • Comparison of Mitosis and Meiosis 10:42
    • Mitosis Vs. Meiosis: Cell Division
    • Mitosis Vs. Meiosis: Daughter Cells
    • Meiosis: Pairing of Homologous Chromosomes
  • Mitosis and Meiosis 14:21
    • Process of Mitosis
    • Process of Meiosis
  • Synapsis and Crossing Over 19:14
    • Prophase I: Synapsis and Crossing Over
    • Chiasmata
  • Meiosis I 25:49
    • Prophase I: Crossing Over
    • Metaphase I: Homologs Line Up
    • Anaphase I: Homologs Separate
    • Telophase I and Cytokinesis
    • Independent Assortment
  • Meiosis II 32:17
    • Propphase II
    • Metaphase II
    • Anaphase II
    • Telophase II
    • Cytokinesis
  • Summary of Meiosis 38:15
    • Summary of Meiosis
    • Cell Division Mechanism in Plants
  • 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

Transcription: Meiosis

Welcome to Educator.com0000

This is the third in a series of lectures on cell reproduction, and we will be focusing on the topic of meiosis.0002

To understand meiosis, you also need to understand chromosome number and sets of chromosomes.0013

There are two general types of cells in terms of the number of chromosome sets: haploid cells and diploid cells.0021

Diploid cells have two sets of chromosomes. Somatic cells are diploid, so what are somatic cells?0030

Well, they are any cells in the body that are not reproductive cells.0036

Gametes or sperm and egg are reproductive cells. Other cells are somatic cells, for example cells of the skin, of the kidney, of the eye.0042

Those are all somatic cells. These cells are diploid and contain two sets of chromosomes.0054

The previous lecture covered mitosis, and somatic cells are reproduced via mitosis.0061

If you have not watched that lecture yet, it would be a good idea to start out with that because it explains some basic concepts.0067

And meiosis is more complicated than mitosis, so it is important to have a good understanding of that before you move on.0073

Now, with meiosis, what we are focusing on is cell division that reduces chromosome number and produces gametes.0081

Gametes, as I mentioned sperm and eggs, are produced via meiosis, and these cells are haploid. They contain only one set of chromosomes.0092

It is easiest to understand this by using an example.0101

Each species has a particular chromosome number. Humans have 46 chromosomes in diploid cells and somatic cells.0105

These actually consist of two sets. Each set contains 23 chromosomes.0123

We will often talk about diploid and say "oh, the cell is 2n". 2n equals a diploid cell.0130

Here, since we have, for humans, two sets of 23 chromosomes, n, therefore equals 23. 2n equals 46.0138

A chromosome with n is considered haploid. A chromosome with 2n sets of chromosomes is considered diploid.0157

Looking a little bit more deeply, diploid cells have 46 chromosomes consisting of two sets, and each of those chromosome pairs is given a number.0170

So, 23 sets, and we number 1 through 22 actually, and then the 23rd set are the sex chromosomes.0189

Let's say you are looking at chromosome 2, chromosome 2, an individual would have - say this is chromosome 2 and then, this is another chromosome 2 - two of these0203

chromosome 2s, one maternally derived and then, another chromosome 2 from the father, paternally derived.0220

These two chromosomes together are called a homologous pair or sometimes just homologues.0236

Each chromosome, like chromosome 1, chromosome 2, chromosome 2, has a particular size, centromere placement and banding pattern. They also carry alleles for particular traits.0250

For example, let's say one chromosome looks like this, and that is chromosome 1; and there is another one similar to chromosome 1.0265

Now, maybe I have another chromosome that has very short, short arms and much longer long arms, so different shape, a different centromere placement, and let's say this is chromosome 4.0274

So, homologous chromosomes are going to be the same length. They are going to have the centromere placements so the same proportions, and they will also have the same banding or staining pattern.0288

In the lab, when we want to visualize chromosomes within cells, we can stain them, and when you stain, you will see certain bands like, maybe this one bands up here and here and here and down here.0298

Its homologue is going to do the same, and then, this one might be different. It might have just a band right here and then, one right here.0309

These have similar banding patterns, similar lengths, or same, same banding patterns, not just similar- same lengths, same centromere placements.0319

These are homologous chromosomes.0328

In a diploid cell, chromosomes 1 through 22 are going to be found in homologous pairs, and these are called autosomes.0330

1 through 22, and you have two of each autosome- two 1s, two 2s, two 3s, now, the 23rd set plus 1 set of sex chromosomes.0344

Chromosomes 1 through 22 are autosomes. That 23rd set is the sex chromosomes.0355

So, looking a little bit more carefully at how sex chromosomes work, in a diploid cell in an individual, if their sex chromosome pair that they have is XX, that individual is a female.0361

If the chromosome pair is XY, that individual is a male.0378

This is in diploid cells. There is going to be 1 through 22, two sets- one that the individual got from the mother, one that they got from the father.0386

In sex chromosomes, the individual is going to have XX if they are a female and XY if they are a male.0394

One of these Xs comes from the mother, in a female. The other comes from the father, in a female, in a male.0405

One X came from the mother, and then, the Y came from the father.0413

This is focusing on diploid cells.0421

What we are going to be talking about today is the production of haploid cells or the production of gametes via meiosis.0424

Gametes, sperm and egg, do not contain homologous pairs. In fact, they will only have one chromosome 1, one chromosome 2, one chromosome 3 and either an X or a Y.0433

Egg cells will only carry Xs because the female producing these eggs only has Xs.0452

Sperm, half the sperm will contain an X. Half will contain a Y.0458

Something else to note is these chromosomes and homologous pairs do not just look the same. They are not just the same length and the same banding pattern.0466

Much more important than that is they carry alleles for the same traits. An allele is an alternative form of the gene for a trait, for example, eye color.0478

One could have an allele for blue eyes, so they have DNA that would encode for the eye color to be blue.0501

Another allele could be brown eyes. Another could be green eyes.0509

Hair color: there could be an allele for blonde hair. Someone could have an allele for black hair.0514

Now, let's look at these chromosomes. Chromosome 1, let's say that it does carry the information for eye color.0520

Let's say it is right up here at the tip. Maybe this chromosome came from the individual's mother, and that mother gave a blue eye allele right there.0528

The father might have given a different form, brown eyes.0544

So, diploid cells are carrying two chromosomes of each type - except for the sex chromosomes, and the male can be XY - that carry alleles for the same traits like the eye color allele.0548

The eye color allele is here, and this could be blue eye. This could be brown, or they could both be blue.0563

Maybe chromosome 4 contains the allele for hair color, and this individual may have gotten the allele for black hair from his mother and the allele for brown hair from his father.0567

Diploid cells contain two alleles for each trait. Haploid cells would not.0580

Half of the information has been lost, so if this goes from being diploid to being haploid, that egg cell, for example, may only carry the blue eye trait0588

and the black hair trait, or the blue eye trait and the brown hair trait.0600

This allows for genic variation, which we are going to talk about more in a moment.0604

For right now, the important thing to know is diploid cells, somatic cells, are produced via mitosis. They contain two complete cells of chromosomes.0609

Haploid cells are produced via meiosis, so spermatogenesis, production of sperm and oogenesis, production of eggs that we will talk about later in the course in more detail, are produced via meiosis.0617

Right now, we are just going to focus on that process of meiosis and reduction of chromosome number to create four haploid cells that are non-identical.0632

I am going to go talk about a comparison of mitosis and meiosis to give you an overview before we go into the details of meiosis.0644

Again, if you have not learned mitosis, it would be a really good idea to go back, cover that now, make sure you have that down before you proceed.0652

In mitosis, there is one round of cell division, and recall that there are four phases: prophase, metaphase, anaphase and telophase.0659

In meiosis, there are actually two rounds of cell division: meiosis 1 and meiosis 2.0682

If the cell goes through prophase, which is called prophase 1, then, it goes to metaphase 1, anaphase 1 and telophase 1.0690

And some of the events during this phase are quite different than the events of mitosis.0705

There is also after this occurs, the parent cells sorts out. Meiosis 1 occurs, and you end up with two non-identical daughter cells that, then, continue on into meiosis 2.0712

You end up with four cells because two rounds of cell division.0731

The second round of cell division, meiosis 2, you have prophase 2, metaphase 2, anaphase 2 and telophase 2.0736

This is actually very similar to mitosis, the second round of cell division.0746

Mitosis, one round PMAT, meiosis, two rounds of PMAT resulting in two identical daughter cells with mitosis because this is only one round of cell division.0752

Here, you get 1, 2, 3, 4 daughter cells, and they are non-identical.0764

Extremely important is that the daughter cells of mitosis are diploid.0771

They contain two sets of chromosomes. We often say they are 2n.0776

The daughter cells produced via meiosis are haploid. They are n.0782

They are non-identical, so if you took four different eggs produced by a female, you would see that one may carry an allele from blue eyes.0790

One might carry brown eyes. One egg might have blue eyes but a gene for being short.0801

The other might have brown eyes but a gene for being tall.0807

All kinds of mixing and matching allow for huge amount of genetic variation, and it is the reason that the offspring of a couple do not all look identical.0810

In order for some of this mixing, matching genetic variation to occur, a very important event occurs in prophase 1 that we are going to discuss in just a moment,0821

and that is pairing of homologous chromosomes with exchange of DNA.0829

Crossing over is exchange of DNA between homologous chromosomes.0834

Mitosis: one round of cell division, the result is two daughter cells that are diploid.0841

They are identical to each other. They are identical to the parent cells.0846

Meiosis: two rounds of cell division, non-identical daughter cells with pairing over - excuse - pairing of homologous chromosomes and crossing over.0850

In summary, mitosis and meiosis, here, we have mitosis right here, and on the other side is meiosis.0862

This parent cell is diploid. This individual has, let's call this chromosome 1 and chromosome 2.0880

This individual, this could be, say, a skin cell from someone. That skin cell has a chromosome from that person's mother, chromosome 1 and a chromosome 1 from the person's father.0888

These two together are homologues.0900

This individual has a chromosome 2 from their mother and from their father, another homologous pair.0905

Now, in humans, there would be 22 of these pairs plus a pair of sex chromosomes.0911

Mitosis occurs. This diploid cell divides into two daughter cells that are identical and diploid.0917

1, 2, 3, 4 chromosomes, there is still 1, 2, 3, 4 chromosomes. These chromosomes here, because the cell has been through S phase, it has been through synthesis of the DNA,0928

the DNA was copied, so there are sister chromatids that identical to each other; so no information has been lost.0939

One cell got this chromatid. The other got this chromatid.0948

They are identical. Everything here, all of these, contain the same genetic information.0952

If there is a blue-eyed allele here and brown-eyed allele here, this individual still has the blue eye allele and the brown.0956

If there is a tall allele here and a short allele here, tall, short, no information has been lost- very different from meiosis.0963

In meiosis, this individual also started out diploid.0972

This would be a cell, for example, that produces sperm.0977

Spermatogenesis, the production of sperm, starting out with the cell and going through meiosis.0983

M1 occurs here. M2 is occurring right here.0991

This individual started out with two chromosome 1s, two chromosome 2s.0997

By the end of that first division, M1, these cells are already haploid.1004

1, 2, 3, 4 chromosomes, there is only 2 chromosomes by the end of meiosis 1, so information has been lost.1009

Another very important fact is that these sister chromatids are no longer identical, and we will see why in a minute.1019

It has to do with that exchange of segments of DNA between homologous chromosomes.1027

Here, the homologous pairs have been split up.1033

There is one chromosome 1 here. There is one chromosome 1 here.1036

There is one chromosome 2 here. There is one chromosome 2 here.1040

These cells are no longer identical. Information has been lost.1047

Maybe there is a blue eye allele here, and there was a brown eye allele here.1051

Well, now, this cell has the blue eye allele, but the brown allele is gone. This cells the brown-eyed allele, blue-eyed allele is gone.1057

The gene for short stature might be down here, and tall stature might be up here.1067

Not all the information is there, so the cell is different.1074

Then, in meiosis 2, sister chromatids separate.1077

In this phase, we have the reduction of chromosome number. Now, we have sister chromatids separating, and I will go over all this in detail.1082

But just as an overview, you started out with a diploid parent cell. You end up with four haploid non-identical daughter cells.1089

Diploid cell, two diploid daughter cells identical, diploid cell starts out. You end up with four gametes that are non-identical.1099

For spermatogenesis, you actually do end up with four sperm cells.1109

The production of ovum, of eggs is a little bit different. You actually do not end up with four eggs.1114

We will talk about that in detail and the reproduction, but just so you know now, you will actually only end up with one ovum and other cells that are called one ovum plus polar bodies, which are dead ends.1121

They cannot create an offspring.1136

Spermatogenesis, there are four sperm cells produced, but the process is the same as far as the steps of meiosis and mitosis - excuse me - steps of meiosis 1 and meiosis 2.1140

Alright, looking at prophase 1 to start, prophase 1 is extremely important step in creating genetic variation, genetic variability within the sexually reproducing species.1155

During prophase 1 in meiosis, homologous chromosomes pair up.1172

Nothing like this happens in mitosis, and this process of pairing up is called synapsis.1178

Crossing over is the exchange of DNA between homologous chromosomes.1189

Here, looking at these long chromosomes, let's call this one and one, as usual, and the shorter ones two and two.1195

This is a homologous pair. These homologous pairs, this is a homologous pair, and when they pair up like this, they form what is called a tetrad.1201

Homologous pair means two chromosome 1s, two chromosome 2s, two chromosome 3s.1217

Now, paired up like this, we would call a tetrad because there is 1, 2, 3, 4 chromatids.1221

Another word you might hear is bivalent for the two chromosomes together, so a tetrad or a bivalent.1227

Synapses is this pairing up process. Crossing over is the exchange of DNA.1236

The DNA that is exchanged is between corresponding alleles, meaning alleles that code for the same traits.1243

Right here, where these two are crossing over, let's say that eye color is controlled right here.1250

And again, let's say this purple chromosome 1 contains DNA coding for blue eyes, and the green chromosome contains DNA coding for brown eyes. These two could swap.1258

Now, I have this whole chromosome that, maybe, came from my father and this whole chromosome that came from my mother, but they are different now.1272

This chromosome from my father started out with a brown-eyed allele. Now, it has all my father's DNA but with the blue-eyed allele.1280

The maternally derived chromosome has all this DNA derived from my mother but with the brown-eyed allele that started out with my father.1289

It is swapping up corresponding DNA. Maybe these two are exchanging the allele for height, the DNA that encodes for height.1297

This chromosome might have short stature encoded, and this chromosome might have tall stature; and these swapped.1308

This allows for a huge variability in offspring because traits have been mixed and matched.1315

A child might end up with or one child has brown eyes and black hair. Another child of a couple has blue eyes and blonde hair.1324

And that has to do with obviously the traits of the two different parents, but also within those parents, the fact that the sperm and egg within a parent, the eggs that a female is carrying are not identical.1336

The DNA has been mixed and matched.1349

Now, some terminology, the physical manifestation of crossing over is called chiasmata.1354

This is a physical manifestation. These regions here, where I can literally see, that is where crossing over is occurring.1362

And crossing over occurs at about one to three places per chromosome.1374

Here, crossing over is occurring in two, and on this one, two as well, but it could be on one place, three places roughly, on one to three.1382

And these x-shaped regions here chiasmata are the physical manifestation of crossing over.1395

OK, synapsis is the process of the pairing of homologous chromosomes. Crossing over is the exchange of DNA between corresponding alleles, corresponding segments.1403

And chiasmata are the physical manifestation of crossing over.1418

Prophase 1: crossing over occurs, but I do not want to have you not realize that the usual events of prophase occur as well.1424

Remember, in mitosis, in addition, in prophase, we saw the breakdown of the nuclear membrane.1431

You should realize that in prophase 1 here, P1, there is still a breakdown of the nuclear membrane occurring, formation of the spindle apparatus.1440

Recall that the spindle apparatus consists of centrosomes, and within those centrosomes are the centrioles.1455

Again, this is a review from mitosis lecture.1467

Spindle fibers, which will eventually attach to the kinetochores on the chromosomes.1472

Breakdown of the nuclear membrane, formation of the spindle apparatus, also the nucleoli disappear. Finally, the chromatin condenses.1483

Remember that, for most of the cell cycle, if you took a cell just a G1 or something, you would not be able to see the chromosomes of the light microscope.1502

You can only visualize chromosomes of the light microscope after they have condensed, and this is how we picture chromosomes or this x shape.1512

And that is what you see with the light microscope once prophase has occurred, and a chromatin has condensed.1519

The fifth is crossing over, synapsis and crossing over.1527

Five events in prophase: breakdown of the nuclear membrane, formation of the spindle apparatus, the nucleoli disappear.1531

The chromatin condenses, and finally, crossing over occurs, and the crossing over is the exchange of DNA between homologous chromosomes.1540

Continuing on with meiosis 1, we just discussed prophase 1 in detail, and do not forget crossing over. It is a big thing to remember.1550

Now, let's look at metaphase 1.1561

Immediately, you will notice that this chromosome contains some DNA from the homologous pair. This is the result of crossing over.1565

These homologues are so closely associated, but crossing over is complete.1578

Also notice that these sister chromatids are not identical anymore.1585

If with mitosis, I emphasize "OK, these sister chromatids are identical".1589

If one sister chromatid goes into one cell, and one goes into the other, fine, everything, all the information is there.1593

That is not true here because this has crossed over.1599

It has exchanged DNA with the homologue. This chromatid has not.1603

Therefore, let's say this has the gene for blue eyes, and this green one is brown eyes.1608

These pieces of DNA are not identical.1620

Here, purple, they might have the blue. It still has the blue eye.1622

This one crossed over, and now it has the brown eye.1627

Before, these chromatids were identical so that this segment was brown-eyed, brown-eyed allele, chromatids that have the brown-eyed allele.1630

On this other chromosome 1, blue eye, blue eye- identical.1639

Now, I have got chromatids that are not identical- blue-eyed on one, brown-eyed on the other, blue-eyed on one, brown-eyed on the other, same here with number two.1647

Again, this increases genetic variation a great deal because the offspring are going to have different combination of chromosomes in the parents and then, each other.1659

Now, metaphase 1, you see that chromosomes line up on the metaphase plate but in a much different way than in mitosis.1669

Homologues line up on the metaphase plate.1682

In mitosis, the lining up was single file. Here, it is double file.1689

The chromosome 1s are next to each other. The chromosome 2s are next to each other, and that is because in anaphase, homologues separate.1694

Sister chromatids do not separate. Homologues separate.1710

The spindle fiber are going to attach from one pole to the kinetochore in one chromosome, from the other pole, to the kinetochore and the other chromosome.1716

And they are going to separate those homologous pairs. They are not going to separate chromatids.1728

Here, I have 1, 2, 3, 4 chromosomes.1737

They are attached. They are very closely associated especially in crossing over, but if I count what are separate chromosomes, I have four.1743

These are being separated to the two poles of the cell.1753

The result is, after telophase 1 and then, subsequent cytokinesis, in which the daughter cells separate, once these separate completely, there will be two cells with only 1, 2 chromosomes each.1756

This cell is now haploid. Therefore, meiosis 1 is called the reductive division.1773

The reduction in chromosome number occurs during meiosis 1.1783

In telophase 1, in some species, the nuclear membrane actually reforms and spindle apparatus breaks down and all, not in all species though1791

because this cell is going to go straight into another round of prophase, metaphase, anaphase, telophase.1801

And then, in some species, the nuclear membrane does not completely reform and everything.1808

It just goes straight into meiosis 2, but in some species, what you would see in telophase is reforming of the nuclear membrane, the nucleoli reappearing and everything. In others, you do not.1812

Prophase 1: cross pairing of homologues and crossing over.1825

Metaphase 1: lining up of homologous pairs on the metaphase plate, double file line.1830

Anaphase 1: homologues separate.1840

Telophase 1: you now have in one of the daughter nucleoli, haploid number of chromosomes, and the other daughter nucleoli, haploid number of chromosomes.1844

I talked about crossing over as a means of providing for genetic variation.1859

Another means is something called independent assortment.1865

What that means is that what one homologous pair does is independent of what another homologous pair does.1871

You see here, the chromosome 1s, the green paternally derived chromosome 1 homologue, went into this cell. Oops, this should be two.1879

For chromosome 2, the purple maternally derived one went into this cell. That was random chance.1892

It could have just as easily bend if these would align up differently that the green chromosome 1 ended up in here, and the green chromosome 2 could have ended up in here.1898

These could have both been green, and for chromosome 3, it could have been a purple one, for chromosome 4, the paternal one, for chromosome 5, the maternal.1907

It totally this is not as so all the paternally derived go into one cell, and all the maternally go into another. That also allows for genetic variation.1914

The homologous pairs separate out independently of what other homologous pairs are doing. It is independent assortment.1925

Now, meiosis 2 is much easier to understand because it is very similar to what occurs in mitosis.1938

Here, I am showing one cell going through meiosis 2 just to keep the picture simple, but in reality, it started out with that parent cell.1950

It went through M1, meiosis 1, and we ended up with two non-identical daughter cells, haploid.1967

Each of these will go on to meiosis 2.1980

I am only showing one, but this is happening a second time so that there will be a total of four cells.1987

This will split, and you will get 1, 2; and this will split, 3, 4, but for simplicity, I am just showing one of these cells.1993

Remember those are happening twice to create a total of four cells.2000

One meiosis 2 for one cell, and then, a meiosis 2 for the other cell.2005

Alright, at the end of meiosis 1, what we ended up with is a haploid cell.2010

In this case, there is only a chromosome 1 and a chromosome 2, so just two chromosomes.2019

And now, I am just going to go on through prophase 2.2025

Prophase 2, very similar to prophase and mitosis.2030

Nuclear membrane, if it is reformed will break down, spindle apparatus formation, disappearance of nucleoli just like in mitosis.2036

Now, the cell will, then, go on to metaphase 2.2046

Just like in mitosis, the chromosomes line up single file along the metaphase plate.2053

They cannot line up as homologous pairs because there are no homologous pairs anymore.2057

There is only one chromosome 1. It does not have a homologue in the cell.2062

Metaphase 2: chromosomes line up on the metaphase plate.2069

Remember that the metaphase plate is an imaginary plane equidistant between the two centrosomes at the two poles of the cell.2082

Anaphase, this anaphase 2 is very similar to anaphase and mitosis. Sister chromatids separate. What is different is that the sister chromatids are not identical.2091

In mitosis, sister chromatids are identical. This and this would be duplicates.2114

That is no longer the case because crossing over occurred back in prophase 1, so sister chromatids have some differences.2122

They have swapped some genes with their homologue.2127

This one has the brown-eyed allele, we said. This one has the blue-eyed allele.2132

Now, this brown is going to go into one cell with a bunch of other genes maybe tall, curly hair.2141

This one is going have blue eyes but still maybe tall and curly hair, so traits have been mixed and matched.2153

OK, metaphase: we had lining up of chromosomes single file.2159

Anaphase 2: sister chromatids separate.2163

Telophase 2: the usual events of telophase meaning breakdown of the spindle apparatus. Nucleoli reappear.2171

So, this is for telophase 2, breakdown of the spindle apparatus. Nucleoli reappear.2186

The nuclear membrane reforms, so I will just put membrane - but it is a nuclear membrane - reforms, and also the chromosomes decondense.2209

Here is finishing up cytokinesis, which starts in late anaphase but finishes up after mitosis.2221

The result is going to be these two cells, and remember that, another daughter cell also went through meiosis 2, so there will be actually a total of four cells:2229

one daughter cell here, one daughter cell went through its own meiosis 2, and the result is going to be actually 1, 2, 3, 4, 1, 2, 3, 4 daughter cells.2244

They each have a chromosome 1 and 2, but some information has been lost. Some things have been mixed and matched.2255

This sperm might encode for traits of blue eyes, curly hair and short, and this one has brown eyes, straight hair and tall. It does not have both alleles in it.2267

That allows for a huge amount of genetic variation, which confers a survival advantage on species that reproduce sexually.2283

Alright, to sum up meiosis is the production of four non-identical daughter cells that are haploid.2296

This occurs for gamete production, production of sperm and egg.2304

The cell starts out as a diploid cell, in this case, four chromosomes, two of one type, two of the other, so two pairs of chromosomes.2310

The cell will go through meiosis 1, and after meiosis 1, the result will be two non-identical daughter cells that are haploid.2321

Remember, meiosis one is the reductive division. There has been a decrease in chromosome number.2332

During prophase 1, crossing over between homologous chromosomes occurred.2339

So, these sister chromatids are no longer identical because crossing over, exchange of DNA, has occurred between the homologous chromosomes.2343

Meiosis 1, we get two non-identical haploid daughter cells.2352

Both of these daughter cells proceed through meiosis 2 if we are talking about spermatogenesis.2359

Oogenesis, production of eggs, is a little more complicated. The polar bodies do not proceed through.2368

We will talk about that in more detail in the reproduction section. Right now, let's focus on spermatogenesis.2376

Spermatogenesis, the result is going to be separation of the sister chromatids during meiosis 2, and now, we have four daughter cells that are haploid and non-identical; and these are haploid.2384

They have one set of chromosomes. In humans, each of these sperm cells would carry 23 chromosomes.2409

Now, let's go a step further.2418

A sperm cell in a human is going to be haploid. It is going to have 23 chromosomes.2421

Fertilization will occur, so the sperm will fertilize an egg to form a zygote.2431

The zygote is diploid because the sperm contains 23 chromosomes. It was n.2441

The egg contains 23 chromosomes, n, so a chromosome 1, a chromosome 2, all the way down and then, either an X or a Y for the sperm and then, just an X for the egg.2450

So, 23 and 23 gives 46 back or 2n. The zygote is now diploid- 46 chromosomes or 2n.2462

The zygote is diploid through the fertilization, which combines the set of chromosomes from the sperm and from the egg to form, now, a single cell that is diploid.2474

The zygote will undergo mitosis to form an embryo, continue on with more mitosis and specialization of cell types to form a fetus, eventually a child and then, adult, so continued mitosis for growth.2493

But, as you can see here, the only time you get meiosis in an animal is to form sperm or egg, to form the gametes.2519

I just want to note that this is actually different than what occurs in plants.2530

We will talk about this more in the plant section, but in plants, haploid cells can actually undergo mitosis.2533

The result is a multicellular organism, so a plant called a gametophyte.2544

This is an actually multicellular organism, but it is haploid. We do not see that in animals.2554

There are no people walking around who are haploid. Everyone you see walking around has diploid somatic cells.2566

The only cells in their body that are haploid are gametes, whereas plants, if you look in a map of moss, what you are primarily seeing are haploid plants.2572

Most plants around, trees and things, are actually diploid, the adult form, but in moss, the haploid gametophyte is just the regular plant form that you mainly see.2584

This is just important to know to take a broader view, not just of the human life cycle or the animal life cycle in biology,2596

but also the different life cycles such as plant life cycle, which we will delve into later in the course.2602

Another fact or factor to keep in mind about meiosis is that if things do not go correctly, the result will be an incorrect chromosome number, either too many or too few chromosomes.2610

And, therefore, the cause can be a genetic syndrome.2626

Mutations of just a single gene can cause diseases such as sickle-cell anemia. However, here, we are talking about something different- actual change in chromosome number.2632

A good example is Down syndrome. Down syndrome is also commonly known as trisomy 21- tri meaning three.2645

An individual, their somatic cells, as you know, should have two of each chromosome.2659

These individuals with Down syndrome actually have three chromosome 21s.2664

This is because there was a nondisjunction meiosis, which created either an egg or a sperm that had an extra chromosome 21 that was then, there when fertilization occurred and zygote was formed.2672

Down syndrome is caused by an extra chromosome 21, and when chromosomes do not separate correctly, that is called nondisjunction.2687

They separate out incorrectly. Either they will have too many chromosomes or they will be missing a chromosome, and then, that will be passed down to the offspring.2699

Many times, nondisjunction would result in an offspring that would not be viable, would not make it very far past the zygote stage, but some of these differences in chromosome number are viable.2710

Down syndrome is one example. Turner syndrome is another.2725

Individuals with Turner syndrome have only one X chromosome.2732

In their cells they have 45 chromosomes. They have the complete set of autosomes, so they have their 44 autosomes, 1 through 22, two sets of those plus an X.2739

These are females with just a single X chromosome instead of XX.2758

So, you can see the medical applications of some genetics and molecular biology and nondisjunction can result in an alteration of chromosome number.2762

First example: has the cell pictured below already undergone DNA replication? How can you tell?2778

In other words, has it been through the S phase, the synthesis phase? Yes.2785

How can I tell? I am looking at these chromosomes, and it is showing actually metaphase.2791

This is showing a cell in metaphase, and I also know that it is metaphase 1 of meiosis because homologous pairs are lined up; and I see that there are sister chromatids.2799

That means that if there are sister chromatids, S phase has occurred.2815

Chromosomes contain sister chromatids. That is how I can tell.2824

How many chromosomes will each daughter cell have after meiosis 1? Will these chromosomes contain sister chromatids?2838

Alright, this cell is going to undergo meiosis 1. It is actually right here.2851

What they are depicting is metaphase 1.2856

Meiosis 1 will occur, and it will go through anaphase and telophase.2861

And you remember in anaphase 1, these sister chromatids are going to separate, so the result is going to be two daughter cells.2867

Homologous chromosomes will separate, so I will end up with one homologue.2877

This one will go here. This one will go here.2882

This one will go here. The other side will end up with this big green one, the medium purple and the small green.2886

Each daughter cell will now be haploid at the end of meiosis 1, and they will each contain three chromosomes. The homologues have separated.2893

Will these chromosomes contain sister chromatids? Yes.2904

The sister chromatids do not separate in meiosis 1. They are still together.2907

Homologues have separated.2911

Now, after meiosis 2, how many chromosomes will each daughter cell contain?2915

After meiosis 2, M2 will occur, and now, sister chromatids are going to separate.2920

So, this cell will still have three 1, 2, 3 chromosomes, but they will not contain sister chromatids anymore, and the same thing will occur down here.2928

At the end of meiosis 2, how many chromosomes will each daughter cell have? Three.2944

This was the reduction division, M1. There is no reduction in chromosome number during meiosis 2.2951

Will these chromosomes contain sister chromatids? No.2957

When one of the gametes resulting from meiosis is fertilized, how many chromosomes will the resulting zygote have?2964

Alright, let's take this and redraw it here.2973

This is the gamete. It is haploid.2977

It has three. It is going to unite with another gamete via fertilization, and those two sets of chromosomes will be brought together in the nucleus of the zygote.2979

And the result is going to be the diploid zygote containing six chromosomes.2992

The parent cell of the gametes start out with 1, 2, 3, 4, 5, 6 diploid cells, six chromosomes. The gametes have three each.3003

Diploidy is restored upon fertilization. 3 + 3 gives 6 2n diploid cell.3012

Example two: match the events of meiosis with the phase during which they occur.3023

One: sister chromatids separate and move to opposite poles.3030

Remember, there are two rounds of meiosis- M1 and M2.3036

During M1, there is separation of homologues. Homologues separate.3041

Meiosis 2 is very similar to mitosis, and sister chromatids separate.3052

If sister chromatids separate, I know I am dealing with meiosis 2, so I have to look for one that is part of the second round of division.3065

Then, I just have to think "OK, which phase, prophase, metaphase, anaphase or telophase 2, during which phase does the actual separation occur?".3075

Well, I know that the separation of chromosomes occurs, separate out into two groups during anaphase.3086

During anaphase 2, it is very similar to mitosis, anaphase and mitosis. Sister chromatids separate.3094

So, the answer for one is E.3101

If we use that one, synapsis and crossing over occur. This is one of the first events of meiosis, so it is the very beginning during the first step, which is prophase 1 right here.3110

Remember, during prophase 1, homologous chromosomes pair up via synapsis. Crossing over occurs.3125

Also, the usual events of prophase are occurring like breakdown of the nuclear membrane, appearance of the nucleoli and formation of the spindle apparatus.3134

Three: homologous pairs line up along the metaphase plate.3145

Well, lining up on the metaphase plate is metaphase, and in metaphase 1, homologues separate - excuse me - in meiosis 1, homologues separate.3149

In order for that to occur, homologous pairs line up double file and so on.3163

In metaphase 1, homologous pairs line up double file, and then, in anaphase 1, there is going to be the separation of these homologous pairs; so this is metaphase 1A.3177

Four: the cleavage furrow forms, and the cells separate into two daughter cells each with one set of chromosomes that do not contain sister chromatids.3194

Cleavage furrow forms during telophase, and there are two rounds of telophase- telophase 1 and telophase 2.3207

This is made easy by the fact that I only have one round here, so it must be C, but let's think a little deeper about this.3215

During meiosis 1, it goes through meiosis 1, and at the end of telophase, homologous pairs have separated. Sister chromatids are not separated.3222

At the end of M1, there are still sister chromatids on each chromosome.3237

At the end of M2, then, you are going to end up with three chromosomes here but each with only one chromatid, so that is telophase 2.3242

Finally, homologous pairs separate and move to opposite poles- anaphase 1.3253

Really important thing to remember is that during meiosis 1, homologues separate, thus reductive division.3259

During meiosis 2, sister chromatids separate.3265

Label the following in the figure below, so chiasmata, tetrad, spindle fibers, centrioles and sister chromatids.3271

What we see here is prophase 1. That crossing over is occurring.3280

The physical manifestation of crossing over is in the form of chiasmata.3285

Now, these two together where I see 1, 2, 3, 4 are what is called a tetrad.3299

These homologous chromosomes paired up, formed a tetrad.3311

Sometimes, they are also known as a bivalent with the two chromosomes.3314

Alright, so it is tetrad.3321

Spindle fibers, you can see, this is just prophase, so the spindle is not completely formed, but the spindle fibers are starting to radiate out or spindle microtubules is the other name.3323

They are starting to radiate out from the centrosome.3335

The centrosome is located in this region, and it is organizing the spindle fibers. It is the MTOC.3340

Within the centrosome lie the centrioles.3346

Finally, sister chromatids, each chromosome, at this point, contains two sister chromatids.3355

They are identical for now, but once crossing over is done, they will not be identical anymore because they have exchanged DNA with their homologue.3365

Here is another set of sister chromatids. Here we have 1, 2 sister chromatids, and they are connected via the centromere.3373

Sister chromatids and then, 1, 2 sister chromatids here, and those four form a tetrad.3385

That covers centrioles, sister chromatids.3394

Describe four differences between mitosis and meiosis.3399

In meiosis, prophase 1, synapsis and crossing over occur.3405

Remember, synapsis is pairing of homologous chromosomes, homologous pairs, and crossing over is the exchange of corresponding segments of DNA between homologous chromosomes.3423

This is unique to meiosis. It does not occur in mitosis.3436

Number one difference: mitosis, no crossing over, no synapsis. That is one difference.3441

Second difference: in meiosis, remember that there are two rounds of cell division- meiosis 1/M1, prophase, metaphase, anaphase and telophase 1; and meiosis 2, prophase, metaphase, anaphase and telophase 2.3454

In mitosis, there is only one round of cell division, so just one round of prophase, metaphase, anaphase, telophase- not two.3481

The result of meiosis is four non-identical daughter cells. Mitosis- very different result: two identical daughter cells.3499

And then, a fourth difference: in meiosis, there is a reduction in chromosome number.3534

The result is that the daughter cells are haploid.3543

In mitosis, there is conservation of chromosome numbers. Therefore, the daughter cells, if the cell starts out diploid, it will continue being diploid.3554

I mentioned in plants, you can have haploid cells and undergo mitosis and stay haploid.3572

What we are talking about focusing on animal cell division, this statement is true.3580

The daughter cells are diploid, but the important point is that with mitosis, it is conservation of chromosome number,3585

whereas with meiosis, it is reduction of chromosome number- having.3597

That makes it a little bit of a broader point that applies.3605

Alright, four differences between mitosis and meiosis: synapsis and crossing over in meiosis, not in mitosis; meiosis, there are two rounds or cell division, PMAT twice,3611

mitosis, there is only one round of cell division, prophase, metaphase, anaphase, telophase 1s; in meiosis, the result is four non-identical daughter cells, mitosis, two identical daughter cells;3625

in meiosis, a reduction of chromosome numbers occurs, so a diploid cell, the daughter cells are haploid, mitosis, the daughter cells are diploid, if you started out with a diploid cell,3638

in other words, there is conservation of chromosome number.3649

This concludes the lecture on meiosis here on Educator.com.3654

Thank you for visiting.3658

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