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Dr. Carleen Eaton

Dr. Carleen Eaton

Reproduction

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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 (23)

0 answers

Post by Tes Dede on January 24, 2016

The presentation of the menstruation cycle is a bit disorganized..

1 answer

Last reply by: Dr Carleen Eaton
Mon Dec 15, 2014 3:52 PM

Post by Rebecca Stevens on December 14, 2014

Great lecture!

1 question regarding this topic: which is contributed by the sperm to the egg during fertilization? centrosome, golgi, kinetochore, mitochondria, none of the above?

I think mitochondria, but I am not sure.

Thanks

3 answers

Last reply by: Dr Carleen Eaton
Sun Apr 27, 2014 6:06 PM

Post by Maria Mohd Zarif on April 25, 2014

When progesterone is produced by the corpus luteum you said progestesrone stimulated development of glands in endomitrium. What glands exactly? Could you give an example?

1 answer

Last reply by: Dr Carleen Eaton
Fri Apr 25, 2014 11:29 AM

Post by Maria Mohd Zarif on April 25, 2014

Why is there a need for 2 feedback mechanisms? When estrogen sends a positive feedback to hypothalamus, why would there be a need to send another one to anterior pituitary? I mean at the beginning of the cycle (from day 1) everything went from one hormone stimulating another. So why is there a need for extra mechanisms the other way around?

1 answer

Last reply by: Dr Carleen Eaton
Fri Apr 25, 2014 11:21 AM

Post by Maria Mohd Zarif on April 25, 2014

Why would the estrogen level be too high in the mid-cycle? If there was already a negative feedback given, that mens that there shouldn't be too much of estrogen? Which means the low level of estrogen will cause a positive feedback that will increase the level of estrogen. Am I wrong?

1 answer

Last reply by: Dr Carleen Eaton
Fri Apr 25, 2014 11:20 AM

Post by Maria Mohd Zarif on April 25, 2014

Does the negative feedback occur (in ovarian cycle) when estrogen is too high in concentration or too low? And the purpose of negative feedback is to stop the production of GnRH so that there are no more follicles maturing?

5 answers

Last reply by: Dr Carleen Eaton
Thu Apr 17, 2014 10:58 AM

Post by sci49 on April 5, 2014

What is the difference between fission and fragmentation? I mean basically in both cases there are parts from which an organism grows up, right?

0 answers

Post by ali aden on July 5, 2013

why does the estrogen exerts negative feedback in early part of the cycle, since there is low amount of estrogen.

My understanding is that negative feedback happens when there is huge amount of something in order to stop producing more.

1 answer

Last reply by: Nahid sohi
Sun Jun 2, 2013 4:13 PM

Post by Muna Lakhani on May 27, 2013

Which hormone has greater effect in production of breast milk--- oxytocin or prolactin?

0 answers

Post by Gayatri Arumugam on March 14, 2012

I found this video very helpful! Thanks!

Reproduction

  • The seminiferous tubules within the testes are the site of sperm production.
  • Spermatogenesis is the process of sperm production. One primary spermatocyte yields four spermatozoa.
  • Oogenesis is discontinuous, with development arrested during prophase I and again in meiosis II. One primary oocyte yields one ovum plus polar bodies.
  • The first half of the menstrual cycle is the follicular phase. Under the influence of follicle stimulating hormone (FSH), a primary oocyte matures within the follicle.
  • The developing follicles produce estrogen, which stimulate the proliferation of the endometrium.
  • An LH surge precedes ovulation. At ovulation the follicle ruptures, releasing an ovum.
  • The second half of the cycle is the luteal phase. The ruptured follicle develops into a corpus luteum under the influence of luteinizing hormone (LH). The corpus luteum produces progesterone.
  • Progesterone maintains the endometrium and stimulates the development of glands within the endometrium. In the absence of pregnancy, the corpus luteum atrophies and the uterine lining is shed.
  • In males, FSH stimulates Sertoli cells, which play a role in sperm development. LH stimulates Leydig cells to produce testosterone.

Reproduction

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
  • Asexual Reproduction 0:17
    • Fragmentation
    • Fission
    • Parthenogenesis
  • Sexual Reproduction 4:00
    • Sexual Reproduction
    • Hermaphrodite
  • The Male Reproduction System 8:54
    • Seminiferous Tubules & Leydig Cells
    • Epididymis
    • Seminal Vesicle
    • Bulbourethral
  • The Female Reproductive System 13:25
    • Ovaries
    • Fallopian
    • Endometrium, Uterus, Cilia, and Cervix
    • Mammary Glands
  • Spermatogenesis 17:08
    • Spermatogenesis
  • Oogenesis 21:01
    • Oogenesis
  • The Menstrual Cycle 27:56
    • The Menstrual Cycle: Ovarian and Uterine Cycle
  • Summary of the Ovarian and Uterine Cycles 42:54
    • Ovarian
    • Uterine
  • Oxytocin and Prolactin 46:33
    • Oxytocin
    • Prolactin
  • Regulation of the Male Reproductive System 47:28
    • Hormones: GnRH, LH, FSH, and Testosterone
  • Fertilization 50:11
    • Fertilization
    • Structures of Egg
    • Acrosomal Reaction
    • Cortical Reaction
  • 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

Transcription: Reproduction

Welcome to Educator.com.0000

In this lecture, we will be covering the topic of reproduction with an emphasis on human reproduction.0002

We are going to start out talking about the two major types of reproduction, which are asexual reproduction and sexual reproduction.0008

Asexual reproduction results in offspring that are genetically identical to the parent.0018

This occurs through mitosis, and via mitosis, daughter cells are produced that carry the same DNA as the parent.0026

Recall that during the survey of animals under the section entitled diversity of life, that group of lectures,0035

I discussed some methods of asexual reproduction as we went through particular types of animals.0043

So, I am going to review some of those now. One type of asexual reproduction is fragmentation.0050

In fragmentation, an entire organism can be regenerated through a fragment of the original animal, so through a piece of the original animal.0058

Fragmentation means regeneration of an entire organism from a piece of the organism.0071

An example is sponges. From a piece of the sponge, can be regenerated an entire sponge.0093

Sea stars can regenerate a portion of the sea star, and there are even a few species that can regenerate an entire sea star just from a piece.0105

A second type of asexual reproduction is fission. In fission, an example, actually, of an organism that undergoes fission is flatworms.0115

And some flatworms, what they do is they can split into two halves, and each half can regrow the missing half.0126

Fragmentation, regeneration from a fragment, whereas, here, if you had a flatworm, and then, it would split in half and regrow the missing half.0148

Another type of asexual reproduction that we discussed was parthenogenesis. In this, the female produces eggs that are not fertilized.0159

But, those eggs, instead, develop into an adult organism, so unfertilized eggs develop into an adult.0173

Examples of organisms that can reproduce this way would be rotifers also honeybees. There are even some reptiles that can reproduce this way.0192

Now, asexual reproduction requires only one parent, whereas, sexual reproduction requires two.0206

And so, there is an inherent efficiency and advantage in asexual reproduction, yet, the dominant mode of reproduction in animals is sexual reproduction.0212

Therefore, there are competitive advantages for the survival of the specie via sexual reproduction, and we are going to talk about that now.0223

And we are also going to just introduce the topic of sexual reproduction and then, go on to talk about the human reproductive system.0234

So, sexual reproduction requires a sperm and an egg, and these two haploid gametes join to produce a diploid zygote.0243

And I just talked about advantages of asexual over sexual reproduction that would0255

make it seem as though asexual reproduction would have won out in the end.0261

And I want to talk about a way in which to view this, which is called the two-fold cost of sexual reproduction.0265

The best way to understand this is to take an example.0279

So, let's say you have a group that is reproducing asexually and another group that is reproducing sexually.0282

And what happens here is we have a female, and she produces, let's say, two offspring.0294

Both of those offspring will also be females, so let's say it is typical in these populations for there to be about two offspring per female.0307

Now, over here in sexual reproduction, this female with a male mate will also produce two offspring.0317

On average, half of the offspring of a female will be male.0333

On average, half of the offspring will be male, half will be female, so here, she has two offspring: one is female, one is male.0339

Now, these two offspring each have two offspring.0347

Now, by the 1, 2, 3, third generation, we are up to four individuals. These are all female.0358

Over here, the male cannot give birth, so we are just counting per female how many individuals are born.0367

And here, we have again this female gives birth to one female, one male. Now, what is happening is that this population is growing more quickly.0376

So, you would expect that asexual reproduction would confer a survival advantage.0387

There is this two-fold cost of sexual reproduction, and yet, this is still the dominant mode of reproduction.0394

What is the advantage to sexual reproduction in terms of the survival of the population?0398

Well, there are a lot of theories on what the advantage is.0404

And one of the major ones, the advantage to sexual reproduction, is the increase in genetic variation in the offspring.0409

And then, that is what accounts for sexual reproduction having one out.0418

What sexual reproduction does do is it increases the genetic variation in the population.0422

Remember to check out the lectures on meiosis, because to understand sexual reproduction, you really need to understand meiosis.0430

And in meiosis, there is going to be crossing over and mixing and matching of different genes and then, the reduction division.0438

And then, the haploid sperm is going to unite with the haploid egg.0447

And by bringing together genes/alleles from two different individuals, you are going to get offspring with a huge variety of traits.0452

So, if conditions change, the environment becomes much warmer or much colder,0458

there is more likely to be some individuals in the population who are well-adapted to that change and could survive.0462

So, this is what may account for the overall advantage that sexual reproduction confers on a population.0467

Now, like I said, we are going to be focusing on human reproduction, so we are going to talk about the joining of a sperm and an egg,0477

one, the gamete from a male, one from a female.0486

But, before we go on, I just want to introduce some terminologies you should be familiar with because some organisms are hermaphrodites.0488

And a hermaphrodite is an individual who has both male and female reproductive organs in one/the same individual.0498

And this actually comes from the word Hermaphrodytus. Hermaphrodytus was the son of the Greek god Hermes, and the Greek goddess Aphrodite,0515

so just some terminologies to be aware of.0526

Now, we are going to go on and, now, focus on human reproduction beginning with an overview of the male reproductive system.0529

For the male reproductive system, the testes are the site of production of sperm, and they are located within the scrotum outside the abdominal cavity.0536

This keeps the testes at a lower temperature than the rest of the body, and that is necessary for the normal production of sperm.0546

So, within the testes are the seminiferous tubules, and outside the seminiferous tubules are Leydig cells.0554

Leydig cells are interstitial cells, and seminiferous tubules are the site of sperm production; and Leydig cells are the site of testosterone production.0564

After sperm is produced in the seminiferous tubules, it enters and travels through a duct called the epididymis.0589

While the sperm is traveling through the epididymis, it gains motility. It gains motility traveling through the epididymis.0601

So, sperm become motile during this phase.0620

During ejaculation, the sperm pass through a muscular duct called the vas deferens.0630

And you may have heard of a procedure called a vasectomy, which renders a male infertile.0639

And the way this works is the vas deferens is cut, so that the sperm will not end up in the semen, so they will not be in the ejaculates.0646

After the sperm travels through the epididymis, then, it goes via the muscular vas deferens and then,0658

exits the body via the urethra, so that is what is shown here.0664

The urethra is both part of the excretory system and the reproductive system in males.0670

There are also some different glands that are involved in the male reproductive system, and right here, there are glands called...0679

There are actually two of them. This is a side view, a side cross-section, but back here, there are actually seminal vesicles.0688

And the seminal vesicles, which are located behind the bladder, are involved in the production of semen.0702

Semen contains mucus. It contains prostaglandins, and it is alkaline.0712

It is alkaline. It has got more of a basic pH.0723

It also contains fructose, which provides energy for the sperm.0727

The prostate gland shown right here secretes a milky-looking fluid that is also part of the semen. It is alkaline as well, and it contains anticoagulants.0739

Finally, below the prostate, but now shown here, are the bulbourethral glands.0759

These are actually located...they would be right here below the prostate, in that region.0769

They secrete a clear fluid, and this is released just prior to ejaculation, and what it does is it is alkaline also.0775

And it helps to neutralize any acidic urine that maybe left in the urethra.0786

This clear fluid, though, can end up containing some sperm that are left in the urethra, so it is a clear fluid that can contain some sperm.0791

OK, so this is a summary of the male reproductive system. Now, we are going to go on to the female reproductive system in humans.0802

In females, the gametes, which are eggs, are produced in the ovaries.0809

And we are going to talk in detail about the production of the eggs, as well as the sperm.0814

And we are going to talk about the menstrual cycle and the ovulation and the release of the egg from the follicles.0826

Within the ovaries are follicles, and eggs are produced in these follicles; so they produce eggs.0834

They also are part of the endocrine system as is the testes. Since the testes secrete testosterone, they are an endocrine organ.0842

And the ovaries are endocrine organs, as well, because they produce the hormones estrogen and progesterone.0850

And you will remember back in the endocrine lecture, I briefly mentioned the ovaries and the testes as part of the endocrine system.0858

Females are born with all of the eggs that they will have in contrast to males who produce sperm throughout their lives.0870

We are going to talk about how these eggs are present in the ovary at birth in females, but they are not fully-developed/mature.0880

What we have here connected to the uterus is a fallopian tube. That is also called an oviduct.0891

And after ovulation, the egg is released here into the abdominal cavity, and the cilia from the fallopian tube help to sweep the ovum into the tube.0903

The fallopian tube is also the site of fertilization.0916

So, sperm enters the female reproductive tract and has to make its way into the fallopian tube where fertilization will take place.0924

And then, the fertilized egg will travel into the uterus and then, implant there.0940

The uterus is a very muscular organ. However, it can stretch enough to accommodate an 8, 9 or even larger pound baby or sometimes multiple babies.0948

So, the uterus is capable of stretching quite a bit. It is a muscular organ.0960

The lining of the uterus is called the endometrium, and it is the endometrium that is shed each month during the menstrual cycle.0964

Each month, the endometrium builds up. It is very well-vascularized.0978

This lining builds up and with a great blood supply to support a developing fetus if pregnancy occurs. If pregnancy does not occur, this lining is shed.0982

The cervix is located at the bottom of the uterus, and it is the opening into the vagina/birth canal.0994

The other structures that are not shown here that are part of the female reproductive system are the mammary glands,1005

which produce milk to nurse the offspring.1011

Now that we have talked about both the male and female reproductive system,1022

we are going to look at how gametes are produced first in males, then, in females.1026

The production of sperm is called spermatogenesis, and you will recognize this drawing/figure from our discussion on meiosis.1030

Right now, I am not going to go into the details of meiosis. You should already have a good understanding of meiosis.1038

I am going to, instead, focus on the names and the stages of sperm development that go along with each step of meiosis.1043

We start out actually with a diploid spermatogonium, and this is diploid. You can see that there are two chromosomes.1054

We will call this chromosome 1 and chromosome 2. There are two of each, so this is diploid or 2n.1071

Then, mitosis occurs. There will be two daughter cells, so there will actually be another one over here that we are not going to follow.1076

We are just going to follow one, and it is going to produce a primary spermatocyte.1088

Now, starting out with the primary spermatocyte, then, we get meiosis. We get meiosis I.1115

Meiosis I has a reduction division, so we are still at 2n here; but then, during meiosis I, it goes from 2n, the reduction division, to haploid.1132

So, there is just one of each type of chromosome, so now, these cells are n.1141

The primary spermatocyte undergoes meiosis I. The result is two secondary spermatocytes.1146

Each secondary spermatocyte undergoes meiosis II, so M II right here, to result in 1, 2, 3, 4 spermatids also haploid.1158

Now, these will go on to mature into spermatozoas, mature sperm cells, so the spermatids are not fully developed.1174

This right here, these are all spermatids and now, spermatozoa, the mature gamete or just sperm cells.1186

To sum up what has happened, from one primary spermatocyte, the result will be four sperm cells.1199

And this is a continuous process, and we are going to contrast that with oogenesis.1214

By continuous process, I mean that meiosis I and meiosis II follow one after the other without disruption, without stopping, without arrest during this process.1220

It is a continuous process. The other thing is that spermatogenesis occurs from puberty onward in males.1234

So, it occurs throughout the lifetime of a male from the time of maturation onward.1248

These are three features of spermatogenesis that you should note and compare with oogenesis.1256

Oogenesis is the production of egg/an ovum, and unlike spermatogenesis, this process is discontinuous.1262

They are arrested for years and even decades at certain stages.1271

So, we will start out with an oogonium. Mitosis occurs, then, the result would be two primary oocytes.1276

We are just going to follow what happens to one primary oocyte.1287

And note that this cell, the oogonium, is diploid. This is diploid.1294

Then, what happens is the primary oocyte begins meiosis.1300

But then, it is arrested in meiosis I until puberty or until that particular cell/follicle matures for ovulation,1306

so arrested in meiosis until puberty or even later, 10, 20, 30 years later.1322

In a developing female in utero, a fetus, what will happen is within her ovaries, the oogonia will start to mature, or they will undergo mitosis.1330

They will form a primary oocyte, and then, in the ovaries of that female fetus, the primary oocytes will start meiosis I.1346

But, they will be arrested - actually, let's be more specific - in prophase I.1356

Then, the female infant is born, so she has ovaries that have millions of primary oocytes arrested in prophase I.1363

And they will stay like that until puberty, and then, at puberty, each month, she will ovulate; and one or sometimes two of these eggs will mature.1373

So, that means that a particular egg could be arrested as a primary oocyte for 12 years, 20 years, 30 years, even longer.1390

Each month, just one or two eggs - usually one - will mature and then, be released.1400

We have the primary oocyte at puberty. It finishes meiosis I, so here, we have meiosis I.1407

When that is completed, what ends up happening is that there is a secondary oocyte and a polar body.1423

So, notice that this is different than spermatogenesis. There are no polar bodies in spermatogenesis.1433

After meiosis I is complete, the cytokinesis is uneven. It is uneven on most of the cytoplasm, and this is due to uneven cytokinesis.1439

Most of the cytoplasm ends up in the secondary oocyte. The polar body is a dead end, so we are haploid at this point.1452

It may divide again. It may not, but it is just, sort of, a by-product of the process.1461

This is not going to become an egg that can be fertilized and develop into an embryo.1466

So, the primary oocyte, a particular month following puberty will mature and finish meiosis I and become a secondary oocyte.1472

Now, there is a second arrest that occurs. The secondary oocyte begins meiosis II, then, stops until fertilization.1484

It is actually a secondary oocyte that is released during ovulation.1503

And if fertilization occurs, that will trigger the secondary oocyte to finish meiosis II and become a mature ovum, and a second polar body results.1507

So, here, we have meiosis II, and this occurs upon fertilization.1521

Just to sum up, in a female developing embryo/fetus in her ovaries, oogonium undergoes mitosis to form primary oocytes.1544

This primary oocytes begin meiosis I.1554

But, they are arrested in prophase I until that particular egg starts to mature during a month that it is going to be ovulated.1557

So, the primary oocyte is arrested at least until puberty in prophase I.1568

At ovulation, meiosis I is completed to yield a secondary oocyte, which is haploid and one polar body.1574

Upon fertilization, if fertilization occurs, meiosis II will be completed to yield one ovum and another polar body.1584

So, comparing this with spermatogenesis, one, oogenesis is discontinuous.1592

There are phases where the process is arrested for years even, when we are talking about meiosis I, so it is discontinuous.1598

And the second difference is that a primary oocyte only results in one ovum.1614

And that is in contrast to a primary spermatocyte that results in four mature sperm cells.1631

Third: oogenesis does not occur throughout a woman's lifetime. It begins at puberty.1637

Well, much of it continues on at puberty. The first steps were taken before birth, but it stops at menopause.1646

Whereas in males, spermatogenesis occurs throughout the male's life.1657

Alright, now, the next thing we are going to talk about is hormonal control of both the male and female reproductive systems.1665

And we will start out by talking about the female reproductive system specifically the menstrual cycle.1672

Now, the development of the egg, of the ovum each month is coordinated with a cycle that prepares the uterus for the implantation of the embryo.1677

What is really happening are two cycles: the ovarian cycle and the uterine cycle.1688

And when we talk about menstruation, what we are really talking about is the uterine cycle,1695

that the monthly cycle of the endometrial lining building up and being shed.1700

However, often, when there is a discussion of the menstrual cycle, both are included because they are very well-coordinated.1705

One has to occur at the same time as the other, side by side, in parallel, because if they were not,1714

then, an egg would be ovulated when the uterus was not ready to accept the pregnancy, and that would just be a waste.1719

I am going to talk about both the ovarian and the uterine cycle together and then,1726

afterwards, summarize which is which and the differences between the two.1730

Now, the first thing to understand are the hormones that are involved in these processes.1735

There is GnRH, which is produced by the hypothalamus, follicle-stimulating hormone and luteinizing hormone,1740

which are produced by the anterior pituitary and estrogen and progesterone, which are produced by the ovaries.1749

We are going to start and assume a 28-day cycle.1760

Cycle days can vary in different individuals, but we are just going assume a standard textbook 28-day cycle.1765

And things begin up in the hypothalamus, and what the hypothalamus produces is gonadotropin-releasing hormone/GnRH.1771

Remember that these releasing hormones that are produced by the hypothalamus act on the anterior pituitary.1782

And the anterior pituitary, then, is stimulated to release its hormones.1789

So, the anterior pituitary in response to GnRH produces follicle-stimulating hormone/FSH and luteinizing hormone/LH.1795

The major player that we are going to talk about in this first half of the cycle is...1813

So, if we are starting a cycle, day 1 up here, the first half of the cycle about the first 14 days, the major player is follicle-stimulating hormone.1820

And its name tells you what it does. It stimulates the ovaries, and it causes the follicles in the ovaries to mature.1830

As these follicles mature, they produce estradiol, which is a form of estrogen, so I am just going to put estrogen.1846

Now, during the early part of the menstrual cycle, estrogen exerts a negative feedback effect on the hypothalamus.1857

So that as the follicles mature, and a few follicles may start maturing, but eventually, one will dominate.1869

That one will take over. It will finish maturing.1877

It will be released at ovulation. Occasionally, two can be released, and that would result in fraternal - non-identical - twins.1879

But, usually, just one dominant follicle matures and is released.1887

Now, this follicle is producing estrogen, and low levels of estrogen have a negative feedback effect on the hypothalamus.1890

So, negative feedback meaning it is going to prevent the hypothalamus from secreting GnRH, which means that FSH levels will be lowered.1897

And this will prevent more and more follicles from maturing, so there is a negative feedback loop here.1909

Now, this first half of the cycle is called the follicular phase, and really, what I have been talking about is the ovarian cycle.1917

This is really what is going on with the ovaries, so first half of the ovarian cycle.1936

We will talk about the uterus in a minute. This is the follicular phase.1941

Sometimes this first half of the cycle is also known as the estrogenic phase because1945

estrogen is the major player here as far as what the ovaries are producing.1950

Now, towards mid-cycle when the follicles are very close to maturation, the estrogen levels build up pretty high.1954

When that happens, the effect that estrogen has is reversed- the effect that it has in the hypothalamus.1966

The same hormone acting on the same endocrine organ, instead of causing negative feedback, now switches and actually gives positive feedback.1974

And it stimulates the release of GnRH.1984

At the same time, high levels of estrogen secretes also has a positive effect on the pituitary to help stimulate the release of LH.1988

So, there are two types of positive effect here: one on the hypothalamus, one on the anterior pituitary.2000

And the result is a greatly increased level of LH, so this positive feedback causes what is called an LH surge.2006

So, I am going to the space here and show LH surge meaning that there is a very rapid large increase in the level of luteinizing hormone.2023

About a day after that LH surge, ovulation occurs.2041

Now, before we go on to talk about ovulation, I will write that down- ovaries. Follicle ruptures, and that is ovulation.2051

In other words, the egg is released, but I want to stop for a second and talk about what is going on in the uterus.2071

I talked about the effects of estrogen as far as the negative and positive feedback in the hypothalamus, but estrogen has another effect, as well.2079

What it is doing over here is also affecting the uterus.2089

And in the first half of the cycle, what is going to happen is estrogen will cause the proliferation of the endometrium.2096

Therefore, the first half of the uterine cycle is called the proliferative phase.2112

And what this is doing is getting the uterus ready for pregnancy so that everything is coordinated.2128

As a woman is about to ovulate, her uterine lining is built-up and ready for an embryo to be implanted.2135

OK, so, where we left with the ovarian cycle is that there was an LH surge.2145

And about a day after that in the ovary, a follicle ruptures the mature follicle and release an egg.2151

So, this is ovulation. This occurs around day 14.2160

All of this is the first half of the cycle. This is the follicular phase, and then, after ovulation...2168

So, up here, above this line is the follicular phase, and in terms of the uterus, it is the proliferative phase.2177

Now, down here, after ovulation, this is what is known as the luteal phase.2189

What is left behind after the follicle ruptures, differentiates into a corpus luteum.2200

In the ovary, there is the follicle. The follicle ruptures.2209

It releases an egg, and what is left behind is stimulated by luteinizing hormone to form a corpus luteum from the ruptured follicle.2212

The corpus luteum secretes progesterone, so now, we have the ovaries are still secreting estrogen.2231

But, now, we have progesterone levels going up.2237

So, in the second half of the phase, this second half is called the luteal phase. It is sometimes also known as the progesteronic phase.2241

Estrogenic- first half; progesteronic- second half; follicular- first half; luteal phase- second half.2248

Progesterone maintains the uterine lining.2258

And it also stimulates the development of glands in the endometrium and increases the blood supply to the uterus.2263

So, I talked about what estrogen does to the uterus. Now, let's talk about the effect of progesterone on the uterus.2270

Progesterone acts on the uterus to stimulate gland development, and it increases the blood supply to the endometrium.2282

And it just maintains that endometrium that was built up during the proliferative phase.2303

This phase is called the secretory phase, and that name comes from the fact that glands secrete substances.2309

The first half of the uterine cycle is the proliferative phase. The second half of the uterine cycle is the secretory phase.2320

Now, estrogen and progesterone secrete a negative feedback effect on the hypothalamus.2330

So, at high levels of estrogen just before ovulation, there is that positive feedback from estrogen, but most of the time, it is doing negative feedback.2340

Now, here, we have the corpus luteum, the ovaries producing progesterone, and the ovary is still producing estrogen.2349

So, I am going to put estrogen here, as well, and what these two are doing, the progesterone and the estrogen, is they are suppressing.2358

They are going back up, and they are suppressing the hypothalamus.2367

Again, we are having negative feedback to the hypothalamus. As a result, GnRH levels drop.2376

LH levels drop, and the corpus luteum atrophies. LH maintains the corpus luteum.2382

One of the things that LH did was stimulated the ovaries to ovulate, and the other thing is for the corpus luteum to develop.2396

Without the influence of LH, the corpus luteum atrophies.2402

So, I am just going to put that right here "decreased LH, corpus luteum atrophies".2407

Since the corpus luteum produces progesterone, when the corpus luteum atrophies, progesterone decreases.2418

If progesterone decreases, there is nothing to maintain the endometrium, the endometrial lining. The lining is shed.2425

Menses occur, so the menstrual cycle is a result of the shedding of this built-up2434

lining because the lining will not be maintained if progesterone levels drop.2444

The LH will only maintain the corpus luteum for a couple of weeks.2450

If no pregnancy results, corpus luteum atrophies, progesterone decreases. The endometrial lining is shed, and they cycle begins again with day 1.2454

Now, let's talk about what happens with pregnancy.2465

If pregnancy occurs, the fetus or the embryo produces hCG. hCG is a hormone called human chorionic gonadotropin- hCG.2470

And hCG is an analogue of LH.2492

Therefore, hCG is capable of maintaining the corpus luteum. What it is essentially doing is rescuing the corpus luteum.2499

If a pregnancy does not result, then, within a couple of weeks after ovulation, LH levels would be low. Corpus luteum will involute.2511

It will atrophy, progesterone drops, menses occur.2522

However, if a pregnancy does result, the fetus, the embryo begins producing hCG.2526

And the hCG can act in the same way as LH maintains the corpus luteum.2533

The corpus luteum keeps making progesterone. They uterine lining is preserved, and the embryo can implant.2542

The pregnancy is maintained. Eventually, the corpus luteum does atrophy, but by then, the fetus and the placenta are developed.2551

And the placenta, then, takes over the role of producing progesterone.2560

And actually, early pregnancy tests that are done in the early part of pregnancy, what they are measuring is hCG.2565

Alright, to go ahead and sum up because that was quite a bit of information,2575

there are two cycles occurring together simultaneously, very well-coordinated.2579

One is the ovarian cycle. The first half is known as the follicular phase.2585

It is also sometimes called the estrogenic phase.2599

And what happens during this phase is FSH stimulates the follicles to develop one dominant follicle ends up taking over.2603

There is a positive feedback effect exerted by the estrogen produced by the developing follicle that causes an LH surge, which triggers ovulation.2615

And an egg is released.2628

The second half of the ovarian cycle is the luteal phase. It is also sometimes called the progesteronic phase.2629

During this part of the cycle, under the influence of LH, a corpus luteum develops from the ruptured follicle.2651

The corpus luteum produces progesterone, which maintains the lining of the uterus and stimulates these glands to develop.2662

However, because progesterone and estrogen exert a negative feedback on the hypothalamus,2675

eventually, within a couple weeks, LH levels will drop low enough.2679

So, the corpus luteum will atrophy, will not be producing enough progesterone, so progesterone levels will drop; and that plays into the uterine cycle.2682

In the first half of the uterine cycle, it is the proliferative phase, and under the influence of estrogen,2694

stimulates the endometrium to proliferate, readying the body for potential pregnancy.2709

In the second half, this is the secretory phase, the progesterone being secreted by the corpus luteum maintains2719

the endometrium and stimulates gland development in the endometrium and an increase in the blood supply.2733

If the corpus luteum does atrophy because of the drop in progesterone when LH drops, then, the endometrium will not be maintained.2753

It will be shed, and that is menstruation.2761

Now, if a pregnancy results, the corpus luteum, remember, hCG can maintain the corpus luteum so that progesterone levels will stay high.2764

And the uterus will be maintained in a state that can support a pregnancy.2777

Alright, so, we talked about most of the hormones involved in a female reproductive system.2785

However, I want to review two more that I mentioned back in the endocrine section, and those are oxytocin and prolactin.2791

Oxytocin, if you will recall, is produced in the hypothalamus but stored in the posterior pituitary.2799

And its function is to stimulate the contraction of the uterus during child birth. In addition, it stimulates the secretion of milk by the mammary glands.2806

So, oxytocin is one, and then, the other hormone you should know is prolactin.2818

Prolactin is actually produced by the anterior pituitary.2824

And it stimulates the development of the mammary glands as well as the production of milk by the mammary glands and lactin, lactate.2828

That helps tell you its function.2837

In addition to the other hormones we talked about, you should keep in mind the roles of these two hormones in the female reproductive system.2840

Now, talking about regulation of the male reproductive system by hormones, there are some similarities especially in the first few steps.2847

So, again, I will start out by talking about the various hormones that are involved, this time, in the male reproductive system.2857

GnRH, which is produced by the hypothalamus, is also a player here. LH and FSH have a role, and in males, the other hormone is testosterone.2863

Again, starting up with the hypothalamus, the hypothalamus secretes gonadotropin-releasing hormone, so same as in females for this step right here.2878

As in females, the GnRH stimulates the anterior pituitary to release follicle-stimulating hormone and luteinizing hormone.2895

Now, here is where things get different in males versus females.2910

What FSH does is it stimulates Sertoli cells. Sertoli cells play a role in the development of sperm.2914

You can look at them as supporting the development of sperm. They help with nutrition and play other roles in the development of sperm.2925

That is FSH. The role of FSH is to stimulate Sertoli cells, which help with the developing sperm.2939

LH stimulates Leydig cells, and if you recall, Leydig cells are interstitial cells in the testes that produce testosterone.2947

So, these produce testosterone. Actually, this is should be...and their role is to produce testosterone.2956

Testosterone has an inhibitory effect on the hypothalamus, so when there is enough testosterone being produced, what it is going to do is go back,2975

suppress the secretion of GnRH by the hypothalamus, which is going to decrease FSH and LH levels and then, decrease testosterone levels.2984

So, we have another negative feedback loop here as we did with estrogen in the early part of the menstrual cycle.2993

Alright, now that we have talked about spermatogenesis, hormonal control of the reproductive systems,3002

oogenesis, we are up to the point of talking about fertilization.3009

Fertilization refers to the union of the sperm and the egg to form a zygote.3013

The sperm is haploid. The egg is haploid, and when those two come together and fuse, they form a diploid zygote.3020

The egg is surrounded by some protective envelopes, and it has an outer transparent envelope called the corona radiata.3028

So, corona radiata is an outer protective envelope.3042

Just beneath the corona radiata...so, the corona radiata, I am going to say, is out here, and then, the next layer is the zona pellucida.3053

There are receptors for sperm on the zona pellucida, and when the sperm binds to the receptors...3069

So, sperm comes along and ends up binding to receptors here, binds to receptors on the zona pellucida.3081

What that triggers is what is called an acrosomal reaction.3094

During the acrosomal reaction, if you look at the head of the sperm, there is this region called the acrosome, and it contains hydrolytic enzymes.3102

So, the sperm that first binds will then trigger this acrosomal reaction, and it is going to start to break down.3113

The sperm will start to break down the zona pellucida. Once it digests this outer membrane, the zona pellucida, it is able to make contact.3127

The head of the sperm can make contact with the plasma membrane of the egg.3136

So, the acrosomal reaction breaks down zona pellucida. Sperm contacts the egg plasma membrane.3140

At that point, a cortical reaction will occur, so that triggers the cortical reaction in the egg.3160

So, we get the sperm-binding receptors on the zona pellucida. That triggers an acrosomal reaction.3172

Enzymes are released.3178

The sperm, then, is able to break through that layer and make contact with the plasma membrane so that the sperm and egg can fuse.3180

Then, this cortical reaction prevents polyspermy. It prevents multiple sperm from fertilizing the egg.3189

What happens is the egg releases the enzymes.3204

So, in the acrosomal reaction, the sperm releases enzymes to break down the zona pellucida.3209

In the cortical reaction, the egg releases the enzymes to prevent the entry of additional sperm.3213

So, contact between the sperm and the plasma membrane of the egg triggers the egg to release enzymes that block the entry of other sperm.3226

And it prevents polyspermy.3237

This is a type of what we call a slow block to polyspermy.3245

There is a second type of block to polyspermy called a fast block to polyspermy, but it does not occur in mammals.3255

It does occur in sea urchins and other organisms that have been used, that have been well-studied as far as fertilization and embryology.3263

So, fast block to polyspermy has a different mechanism than this one, and an animal can even have both mechanisms.3272

What this is, is depolarization of the cell membrane of the egg.3281

When the sperm comes into contact with the cell membrane, in some animals,3298

that will cause a depolarization of the cell membrane of the egg that prevents fertilization by a second sperm.3305

And then, there is another mechanism that is the release of enzymes by the egg to prevent entry of additional sperm.3316

And this is known as the slow block to polyspermy. Mammals only have the slow block.3326

Alright, what we are going to do next is some review on reproduction.3332

Example one: list three differences between spermatogenesis and oogenesis.3338

Well, spermatogenesis is continuous meaning that meiosis I to meiosis II to the formation of sperm occurs without disruption.3343

By contrast, oogenesis, there is an arrest in prophase I, and there is a second arrest in meiosis II; so oogenesis is discontinuous.3364

The second difference is that a primary spermatocyte produces four sperm,3388

whereas a primary oocyte will only produce one egg, plus there will be a couple of polar bodies.3406

A third difference is that spermatogenesis occurs throughout the lifetime of the male. Oogenesis seizes at menopause in females.3420

So, these are three differences between spermatogenesis and oogenesis.3449

Example two: match the following terms to their descriptions:3455

One, epididymis: develops from the ruptured follicle and produces progesterone- well, that is incorrect.3459

The site where sperm gain motility- that is correct.3468

Just to double check though, produce testosterone- that is not true.3472

Structure in which fertilization takes place- not true.3476

So, no. 1, the epididymis is the site where the sperm gain motility.3479

Two, fallopian tubes also known as oviducts: develop from the ruptured follicle and produce progesterone- that is not accurate.3484

Produce testosterone- not accurate. Structure in which fertilization takes place- that is correct, D.3494

Corpus luteum: now, the corpus luteum is what develops from the ruptured follicle.3502

And it does produce progesterone that maintains the lining of the uterus, A.3508

Finally, Leydig cells do produce testosterone, so B, D, A and C.3514

Example three: what role does LH - so, that is luteinizing hormone - play in maintaining pregnancy?3526

Well, recall that what LH does is it maintains the corpus luteum.3533

And that indirectly maintains pregnancy because the corpus luteum produces progesterone. Progesterone maintains the endometrium.3541

Without progesterone influence, the endometrium would shed. The pregnancy would be lost along with that.3557

Therefore, LH is responsible indirectly for maintaining the pregnancy.3563

During what part of the ovarian cycle does estrogen exert negative feedback?3571

Well, recall that during the early part of the cycle, estrogen has a negative feedback effect on the hypothalamus.3576

And this when there are relatively low levels of estrogen.3593

Now, during what part of the ovarian cycle does estrogen exert a positive feedback?3598

So, at mid-cycle, late in the first half, high levels of estrogen have the effect of positive feedback on the hypothalamus.3603

And remember that the result there is going to be an LH surge.3621

Estrogen goes from early part of the cycle, low levels of estrogen, negative feedback, and then, at mid-cycle, it switches.3631

There are high levels of estrogen, and they exert a positive feedback effect.3638

Example four: what hormone prevents atrophy of the corpus luteum when LH levels decrease?3645

LH levels decrease at mid-cycle, and if there is no pregnancy, then, the corpus luteum will atrophy. Progesterone will decrease.3651

The endometrium will shed, and that is menstruation. The cycle will begin again.3662

Now, if there is a pregnancy, the embryo will produce hCG, and hCG is what prevents the corpus luteum from atrophy.3667

And remember, this is only if there is a pregnancy that results.3681

What is the name of the hormone that stimulates uterine contractions? That hormone is oxytocin, OK?3686

Alright, that concludes this lesson on reproduction.3695

Thank you for visiting Educator.com.3699

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