Course Twelve · The Complete Micro-Course

Biology,
one idea at a time.

The whole introductory biology canon, rebuilt as 1133 numbered videos — each one a single idea, built in the order the ideas depend on each other. The largest course on this site, and the first natural science: from what makes a claim scientific to how energy moves through an ecosystem.

1,133 lessons across fourteen units0 of 1133 live

How the course works

Every idea has a number. Every number knows what comes before it.

Biology is usually taught as an enormous vocabulary list with the reasoning left out. This course is built the other way. Chemistry comes before the cell that runs on it; the cell comes before the division that copies it; division comes before the inheritance it explains; inheritance comes before the evolution it makes possible. Nothing appears before the thing it depends on, and every dependency is a number you can follow back.

Three kinds of video: atoms (one definition, mechanism, or distinction, about twenty seconds), procedures (one method, shown step by step — reading a pedigree, tracing a reaction), and capstones (several ideas run together on one real case, from a signal reaching a cell to an infection being cleared).

Dozens of entries exist purely to name a common misconception and sit beside the correct idea, linked in both directions — that evolution is “just a theory,” that organisms evolve because they need to, that energy is recycled through an ecosystem.

The whole map

All 1133 videos, in order.

New videos post daily until the course is complete. Live ones link straight to the short; the rest are on their way.

Unit 1

The Study of Life and the Chemistry of Life

0001 What Biology Is Atom Soon
0003 Natural Science Atom Soon
0005 Basic Science Atom Soon
0007 Applied Science Atom Soon
0010 Observation and Question Atom Soon
0012 Hypothesis Atom Soon
0013 "A Hypothesis Is Just a Guess" Atom Soon
0015 Prediction Atom Soon
0017 Falsifiability Atom Soon
0019 Variable Atom Soon
0021 Control Group Atom Soon
0024 Designing a Controlled Experiment Procedure Soon
0027 Inductive Reasoning Atom Soon
0029 Deductive Reasoning Atom Soon
0031 Descriptive Science and Hypothesis-Based Science Atom Soon
0034 Scientific Theory Atom Soon
0035 "Evolution Is Just a Theory" Atom Soon
0037 Peer Review Atom Soon
0039 The Scientific Method, Applied Capstone Soon
0041 Order Atom Soon
0043 Response to Stimuli Atom Soon
0045 Reproduction Atom Soon
0047 Adaptation Atom Soon
0049 Growth and Development Atom Soon
0051 Homeostasis Atom Soon
0053 Energy Processing Atom Soon
0055 Evolution Atom Soon
0056 Natural Selection Atom Soon
0057 "Organisms Evolve Because They Need To" Atom Soon
0060 Levels of Organization: Atom to Cell Atom Soon
0062 Levels of Organization: Tissue to Organism Atom Soon
0064 Levels of Organization: Population to Biosphere Atom Soon
0067 Prokaryote and Eukaryote Atom Soon
0070 Is a Virus Alive? Atom Soon
0073 Three Domains of Life Atom Soon
0076 Phylogenetic Tree Atom Soon
0111 Matter and Elements Atom Soon
0113 Atomic Structure Atom Soon
0115 Atomic Number and Mass Number Atom Soon
0117 Isotopes Atom Soon
0119 Radioactive Isotopes and Half-Life Atom Soon
0122 Dating a Fossil by Isotope Decay Procedure Soon
0125 Electron Shells and the Octet Rule Atom Soon
0127 Ions Atom Soon
0129 Ionic Bonds Atom Soon
0131 Covalent Bonds Atom Soon
0133 Polar Covalent Bonds Atom Soon
0135 Nonpolar Covalent Bonds Atom Soon
0137 Hydrogen Bonds Atom Soon
0139 Van der Waals Interactions Atom Soon
0142 Water's Polarity Atom Soon
0144 Cohesion and Adhesion Atom Soon
0146 Water's High Heat Capacity Atom Soon
0148 Water's Heat of Vaporization Atom Soon
0150 Water as a Solvent Atom Soon
0152 Why Ice Floats Atom Soon
0155 The pH Scale Atom Soon
0157 Acids Atom Soon
0159 Bases Atom Soon
0161 Buffers Atom Soon
0164 Buffering Blood pH, Worked Procedure Soon
0185 Dehydration Synthesis Atom Soon
0187 Hydrolysis Atom Soon
0190 Monosaccharides Atom Soon
0192 Disaccharides and the Glycosidic Bond Atom Soon
0194 Polysaccharides: Starch and Glycogen Atom Soon
0196 Polysaccharides: Cellulose and Chitin Atom Soon
0199 Fatty Acids: Saturated and Unsaturated Atom Soon
0201 Triglycerides Atom Soon
0203 Phospholipids Atom Soon
0205 Steroids Atom Soon
0208 Amino Acids and the Peptide Bond Atom Soon
0210 Protein Primary Structure Atom Soon
0212 Protein Secondary Structure Atom Soon
0214 Protein Tertiary and Quaternary Structure Atom Soon
0216 Denaturation Atom Soon
0219 Nucleotide Structure Atom Soon
0221 DNA and RNA Atom Soon
0224 Identifying a Macromolecule from Its Monomer Capstone Soon
Unit 2

Cell Structure and the Plasma Membrane

0241 Microscopy and Cell Size Atom Soon
0243 Light and Electron Microscopy Atom Soon
0245 Unified Cell Theory Atom Soon
0247 Four Components Every Cell Shares Atom Soon
0249 Structure of a Prokaryotic Cell Atom Soon
0251 Prokaryotic Surface Structures Atom Soon
0253 Why Cell Size Is Limited Atom Soon
0255 Structure of a Eukaryotic Cell Atom Soon
0257 The Plasma Membrane, Introduced Atom Soon
0259 Microvilli Atom Soon
0261 Cytoplasm and Cytosol Atom Soon
0263 The Nucleus and Nuclear Envelope Atom Soon
0265 Chromatin and Chromosomes Atom Soon
0267 The Nucleolus Atom Soon
0269 Ribosomes Atom Soon
0271 Mitochondria Atom Soon
0273 Chloroplasts Atom Soon
0274 Endosymbiosis Atom Soon
0275 Peroxisomes Atom Soon
0277 Vesicles and Vacuoles Atom Soon
0279 The Centrosome Atom Soon
0281 Lysosomes Atom Soon
0283 The Plant Cell Wall Atom Soon
0285 The Central Vacuole Atom Soon
0287 The Endomembrane System Atom Soon
0289 Rough Endoplasmic Reticulum Atom Soon
0291 Smooth Endoplasmic Reticulum Atom Soon
0293 The Golgi Apparatus Atom Soon
0295 Lysosome Formation within the Endomembrane System Atom Soon
0297 The Cytoskeleton, Introduced Atom Soon
0299 Microfilaments Atom Soon
0301 Intermediate Filaments Atom Soon
0303 Microtubules Atom Soon
0305 Flagella and Cilia Atom Soon
0307 The Extracellular Matrix Atom Soon
0309 Plasmodesmata Atom Soon
0311 Tight Junctions Atom Soon
0312 Desmosomes Atom Soon
0313 Gap Junctions Atom Soon
0316 Identifying a Cell from Its Organelles Capstone Soon
0321 The Fluid Mosaic Model Atom Soon
0323 Membrane Phospholipids, Oriented Atom Soon
0325 Integral and Peripheral Proteins Atom Soon
0327 The Glycocalyx Atom Soon
0328 How a Virus Exploits Membrane Receptors Atom Soon
0329 Membrane Fluidity Atom Soon
0330 Cholesterol's Role in the Membrane Atom Soon
0333 Selective Permeability Atom Soon
0335 Diffusion Atom Soon
0337 Dynamic Equilibrium Atom Soon
0339 Factors Affecting Diffusion Rate Atom Soon
0341 Facilitated Transport Atom Soon
0343 Channel Proteins Atom Soon
0345 Carrier Proteins Atom Soon
0347 Osmosis Atom Soon
0349 Osmolarity and Tonicity Atom Soon
0351 Hypotonic, Isotonic, and Hypertonic Solutions Atom Soon
0352 "Isotonic Means the Same for Every Cell" Atom Soon
0354 Osmotic Lysis and Crenation Atom Soon
0356 Turgor Pressure and Plasmolysis Atom Soon
0358 Active Transport Atom Soon
0360 Electrochemical Gradient Atom Soon
0362 The Sodium-Potassium Pump Atom Soon
0364 Primary and Secondary Active Transport Atom Soon
0366 Uniporters, Symporters, and Antiporters Atom Soon
0368 Endocytosis Atom Soon
0370 Phagocytosis Atom Soon
0372 Pinocytosis Atom Soon
0374 Receptor-Mediated Endocytosis Atom Soon
0376 Exocytosis Atom Soon
0473 Diagnosing a Membrane Transport Failure Capstone Soon
Unit 3

Metabolism, Respiration, and Photosynthesis

0481 Metabolism and Bioenergetics Atom Soon
0483 Anabolic and Catabolic Pathways Atom Soon
0485 The Metabolic Pathway Atom Soon
0487 ATP versus Glucose: Currency and Storage Atom Soon
0489 Kinetic and Potential Energy Atom Soon
0491 Chemical Energy Atom Soon
0493 Gibbs Free Energy and Exergonic/Endergonic Reactions Atom Soon
0494 "Spontaneous Means Instantaneous" Atom Soon
0496 Chemical Equilibrium in an Open System Atom Soon
0498 Activation Energy Atom Soon
0500 Catalysis Lowers Activation Energy Atom Soon
0502 Systems: Open and Closed Atom Soon
0504 The First Law of Thermodynamics Atom Soon
0506 The Second Law of Thermodynamics and Entropy Atom Soon
0508 ATP Structure Atom Soon
0510 ATP Hydrolysis Atom Soon
0512 Energy Coupling and Phosphorylation Atom Soon
0514 Enzymes as Catalysts Atom Soon
0516 The Active Site and Substrate Specificity Atom Soon
0518 Induced Fit Atom Soon
0520 Temperature, pH, and Enzyme Activity Atom Soon
0522 Enzyme Denaturation Atom Soon
0524 Competitive Inhibition Atom Soon
0526 Noncompetitive and Allosteric Inhibition Atom Soon
0528 Cofactors and Coenzymes Atom Soon
0530 Enzyme Compartmentalization Atom Soon
0532 Feedback Inhibition Atom Soon
0534 Redox Reactions Atom Soon
0536 Electron Carriers: NAD+ and FAD Atom Soon
0538 Substrate-Level Phosphorylation Atom Soon
0540 Glycolysis, Overview Atom Soon
0542 The Steps of Glycolysis Procedure Soon
0544 Pyruvate Oxidation to Acetyl CoA Atom Soon
0546 The Citric Acid Cycle: A Closed Loop Atom Soon
0548 Steps of the Citric Acid Cycle Procedure Soon
0550 The Electron Transport Chain, Overview Atom Soon
0552 Steps of the Electron Transport Chain Procedure Soon
0554 Chemiosmosis and ATP Synthase Atom Soon
0556 Why ATP Yield from Glucose Varies Atom Soon
0558 Anaerobic Cellular Respiration Atom Soon
0560 Fermentation, Defined Atom Soon
0562 Lactic Acid Fermentation Atom Soon
0563 "Lactic Acid Causes Muscle Soreness" Atom Soon
0565 Alcohol Fermentation Atom Soon
0567 Glycogen and Other Sugars Feed Glycolysis Atom Soon
0569 Protein Catabolism Connects to Respiration Atom Soon
0571 Lipid Catabolism Connects to Respiration Atom Soon
0573 Regulation of Glycolysis by Phosphofructokinase Atom Soon
0575 Tracing Glucose Through Cellular Respiration Capstone Soon
0577 Photoautotrophs, Heterotrophs, and Chemoautotrophs Atom Soon
0579 The Overall Equation of Photosynthesis Atom Soon
0581 Leaf Structures: Mesophyll, Stomata, and Guard Cells Atom Soon
0583 Two Stages of Photosynthesis Atom Soon
0585 Wavelength and Light Energy Atom Soon
0587 Photosynthetic Pigments: Chlorophyll and Carotenoids Atom Soon
0589 The Absorption Spectrum Atom Soon
0591 Photosystem Structure Atom Soon
0593 Photosystem II and the Splitting of Water Atom Soon
0595 The Chloroplast Electron Transport Chain Atom Soon
0597 Photosystem I and NADPH Formation Atom Soon
0599 Chemiosmosis in the Thylakoid Atom Soon
0601 The Light-Dependent Reactions, Full Sequence Procedure Soon
0603 Carbon Fixation by RuBisCO Atom Soon
0604 Photorespiration: RuBisCO's Oxygenase Activity Atom Soon
0605 The Calvin Cycle: Three Stages Procedure Soon
0606 C4 Photosynthesis: Bundle Sheath Cells and PEP Carboxylase Atom Soon
0607 G3P as the Calvin Cycle's Export Atom Soon
0608 CAM: A Water-Conserving Adaptation Atom Soon
0609 C3, C4, and CAM Compared Procedure Soon
0610 Photosynthesis and Respiration Are Linked, Not Opposed Atom Soon
0612 Energy Flows and Degrades; Matter Cycles Atom Soon
0613 "Energy Is Recycled in an Ecosystem" Atom Soon
0616 Tracing Carbon and Energy Through Photosynthesis Capstone Soon
Unit 4

Cell Communication and Cell Reproduction

0761 Intercellular and Intracellular Signaling Atom Soon
0763 Ligands and Receptors Atom Soon
0765 Paracrine Signaling Atom Soon
0767 Synaptic Signaling, a Paracrine Case Atom Soon
0769 Endocrine Signaling Atom Soon
0771 Autocrine Signaling Atom Soon
0773 Direct Signaling via Gap Junctions and Plasmodesmata Atom Soon
0775 Internal Receptors Atom Soon
0777 Cell-Surface Receptors: Three Domains Atom Soon
0779 Ion Channel-Linked Receptors Atom Soon
0781 G-Protein-Linked Receptors Atom Soon
0783 The G-Protein Activation Cycle Procedure Soon
0785 Enzyme-Linked Receptors and Receptor Tyrosine Kinases Atom Soon
0787 Small Hydrophobic Ligands: Steroid Hormones Atom Soon
0789 Water-Soluble Ligands Atom Soon
0791 Nitric Oxide as a Gaseous Ligand Atom Soon
0793 Signal Transduction and Receptor Dimerization Atom Soon
0795 Upstream and Downstream in a Signaling Cascade Atom Soon
0797 Signal Amplification Atom Soon
0799 Signal Integration Atom Soon
0801 Second Messengers, Defined Atom Soon
0803 Calcium as a Second Messenger Atom Soon
0805 Cyclic AMP as a Second Messenger Atom Soon
0807 The Phosphoinositide Pathway: PIP2 to DAG and IP3 Procedure Soon
0809 Signal Transduction Can Regulate Gene Expression Atom Soon
0811 Signal Transduction Can Alter Metabolism: the Epinephrine Case Atom Soon
0813 Signal Transduction Can Drive Cell Growth Atom Soon
0815 Apoptosis: Programmed Cell Death Atom Soon
0817 Terminating a Signal Atom Soon
0819 Tracing a Ligand from Binding to Cellular Response Capstone Soon
0821 Quorum Sensing in Bacteria Atom Soon
0823 Biofilms Atom Soon
0825 Signaling in Yeast Atom Soon
0827 Genome and Chromosome: Prokaryotic vs. Eukaryotic Atom Soon
0829 Gene and Allele, Locked Terms Atom Soon
0831 Locus and Homologous Chromosomes Atom Soon
0833 Diploid and Haploid Atom Soon
0835 Genes, Traits, and Variation Atom Soon
0837 Chromatin Compaction, Overview Atom Soon
0839 Chromatin Compaction: the Nucleosome Atom Soon
0841 Higher-Order Chromatin Packing Atom Soon
0843 Sister Chromatids and the Centromere Atom Soon
0845 The Cell Cycle: Interphase and the Mitotic Phase Atom Soon
0847 G1 Phase Atom Soon
0849 S Phase Atom Soon
0851 G2 Phase Atom Soon
0853 G0 Phase and Quiescence Atom Soon
0855 Mitosis, Overview Atom Soon
0857 Prophase Atom Soon
0859 Prometaphase and the Kinetochore Atom Soon
0861 Metaphase Atom Soon
0863 Anaphase Atom Soon
0865 Telophase Atom Soon
0867 Cytokinesis in Animal Cells Atom Soon
0869 Cytokinesis in Plant Cells Atom Soon
0871 Mitosis Is Not Meiosis Atom Soon
0873 Tracing One Cell Cycle from G1 through Cytokinesis Capstone Soon
0875 External Regulation of the Cell Cycle Atom Soon
0877 Cell-Cycle Checkpoints, Three Gates Atom Soon
0879 The G1 Checkpoint Atom Soon
0881 The G2 Checkpoint Atom Soon
0883 The M (Spindle) Checkpoint Atom Soon
0885 Cyclins and Cyclin-Dependent Kinases Atom Soon
0887 The Cyclin-Cdk Activation Cycle Procedure Soon
0889 Negative Regulation: Rb, p53, and p21 Atom Soon
0891 p53 and the DNA-Damage Response Atom Soon
0893 Cancer as Uncontrolled Cell Division Atom Soon
0895 Proto-oncogenes and Oncogenes Atom Soon
0897 "An Oncogene Is a Foreign, Invading Gene" Atom Soon
0899 Tumor Suppressor Genes Atom Soon
0901 Cancer as a Multi-Hit, Multi-Generational Process Atom Soon
0903 Binary Fission Atom Soon
0905 The FtsZ Ring Atom Soon
0906 FtsZ and Tubulin: Homologous Structures Atom Soon
0907 Comparing Prokaryotic and Eukaryotic Cell Division Capstone Soon
Unit 5

Meiosis and Mendelian Genetics

0961 Meiosis, Overview Atom Soon
0963 Interphase Before Meiosis Atom Soon
0965 Prophase I: Synapsis and the Synaptonemal Complex Atom Soon
0967 Crossing Over and the Chiasma Atom Soon
0969 The Tetrad Atom Soon
0971 Prometaphase I Atom Soon
0973 Metaphase I and Independent Orientation Atom Soon
0975 Anaphase I Atom Soon
0977 Telophase I and Cytokinesis I Atom Soon
0979 Meiosis II, Overview Atom Soon
0981 Prophase II Through Telophase II Atom Soon
0983 Tracing One Diploid Cell Through Meiosis I and II Procedure Soon
0985 Meiosis Compared to Mitosis: Homolog Pairing and Crossover Atom Soon
0987 Crossing Over as a Source of Genetic Variation Atom Soon
0989 Independent Assortment of Tetrads as a Source of Genetic Variation Atom Soon
0991 Random Fertilization as a Source of Genetic Variation Atom Soon
0993 Tracing Genetic Variation from Prophase I Through Fertilization Capstone Soon
0995 Sexual and Asexual Reproduction Compared Atom Soon
0997 The Diplontic Life Cycle Atom Soon
0999 The Haplontic Life Cycle Atom Soon
1001 The Haplodiplontic Life Cycle Atom Soon
1003 The Evolution of Meiosis, an Open Question Atom Soon
1005 Genetics and Mendel's Historical Context Atom Soon
1007 Mendel's Model System: the Garden Pea Atom Soon
1009 True-Breeding Lines and Controlled Pollination Atom Soon
1011 P0, F1, and F2 Generations Atom Soon
1013 The Monohybrid Cross Atom Soon
1015 Particulate Inheritance Atom Soon
1017 "Inherited Traits Blend Like Mixed Paint" Atom Soon
1019 Mendel's 3:1 Ratio, Observed Atom Soon
1021 The Rule of Addition Atom Soon
1023 The Rule of Multiplication Atom Soon
1025 Applying the Probability Rules to a Genetic Cross Procedure Soon
1027 Genotype and Phenotype, Locked Terms Atom Soon
1029 Homozygous and Heterozygous Atom Soon
1031 Dominant and Recessive Alleles Atom Soon
1033 "Dominant Means More Common" Atom Soon
1035 The Punnett Square Atom Soon
1037 The Testcross Atom Soon
1039 Incomplete Dominance Atom Soon
1041 Codominance Atom Soon
1043 Multiple Alleles: the ABO Blood Group Atom Soon
1045 Lethal Alleles Atom Soon
1047 X-Linked Inheritance Atom Soon
1049 The Law of Dominance Atom Soon
1051 The Law of Segregation Atom Soon
1053 The Physical Basis of Segregation in Meiosis I Atom Soon
1055 The Law of Independent Assortment Atom Soon
1057 The Physical Basis of Independent Assortment in Meiosis I Atom Soon
1059 The Dihybrid Cross Atom Soon
1061 The 9:3:3:1 Ratio Atom Soon
1063 The Forked-Line Method Atom Soon
1065 Solving a Trihybrid Cross with the Probability Method Procedure Soon
1067 Genetic Linkage Atom Soon
1069 Recombination Frequency Atom Soon
1071 Epistasis Atom Soon
1073 Full Dihybrid Cross: Genotype to Phenotype Capstone Soon
1075 Sex-Determination Systems Atom Soon
1077 X-Inactivation and the Barr Body Atom Soon
1079 Reading a Pedigree to Infer a Mode of Inheritance Procedure Soon
Unit 6

Modern Inheritance, DNA, and Gene Expression

1181 The Chromosomal Theory of Inheritance Atom Soon
1183 Morgan's Drosophila Evidence for the Chromosomal Theory Atom Soon
1185 Genetic Maps from Recombination Frequency Atom Soon
1187 Nondisjunction Atom Soon
1189 Aneuploidy Atom Soon
1191 Human Trisomy as a Chromosomal-Disorder Example Atom Soon
1193 Griffith's Transformation Experiment (1928) Atom Soon
1195 Avery, MacLeod, and McCarty (1944) Atom Soon
1197 Hershey and Chase's Blender Experiment (1952) Atom Soon
1199 Franklin and Gosling's X-Ray Diffraction (1953) Atom Soon
1201 Watson and Crick's Double-Helix Model (1953) Atom Soon
1203 The Nucleotide Atom Soon
1205 Complementary Base Pairing Atom Soon
1207 Antiparallel Strand Orientation Atom Soon
1209 The Double Helix's Overall Structure Atom Soon
1211 Meselson and Stahl's Semiconservative-Replication Experiment (1958) Atom Soon
1213 "DNA Replication Keeps One Whole Original Helix Intact" Atom Soon
1215 Origins of Replication Atom Soon
1217 Helicase Atom Soon
1219 Primase and the RNA Primer Atom Soon
1221 DNA Polymerase's 5'-to-3' Directionality Atom Soon
1223 The Leading Strand Atom Soon
1225 The Lagging Strand and Okazaki Fragments Atom Soon
1227 DNA Ligase Atom Soon
1229 Tracing One Replication Fork from Origin to Ligation Procedure Soon
1231 Prokaryotic Replication's Single Circular Origin Atom Soon
1233 Eukaryotic Replication's Multiple Origins and Polymerases Atom Soon
1235 Telomeres and the End-Replication Problem Atom Soon
1237 Telomerase Atom Soon
1239 DNA Polymerase Proofreading Atom Soon
1241 Mismatch Repair Atom Soon
1243 Nucleotide Excision Repair Atom Soon
1245 Tracing DNA from Structure Through Replication and Repair Capstone Soon
1247 The Central Dogma Atom Soon
1249 The Genetic Code's Triplet Codons Atom Soon
1251 Codon Degeneracy Atom Soon
1253 The Wobble Hypothesis Atom Soon
1255 The Reading Frame Atom Soon
1257 Start and Stop Codons Atom Soon
1259 Prokaryotic RNA Polymerase and the Promoter Atom Soon
1261 Sigma Factor Atom Soon
1263 Prokaryotic Transcription Elongation and Termination Atom Soon
1265 Eukaryotic RNA Polymerases I, II, and III Atom Soon
1267 The Eukaryotic Promoter: the TATA Box Atom Soon
1269 Eukaryotic Transcription Factors Assembling the Initiation Complex Atom Soon
1271 The 5' Cap Atom Soon
1273 The Poly-A Tail Atom Soon
1275 Introns and Exons Atom Soon
1277 Splicing and the Spliceosome Atom Soon
1279 The 5' and 3' Untranslated Regions Atom Soon
1281 Tracing Pre-mRNA Processing from Transcription to a Mature mRNA Procedure Soon
1283 Ribosome Structure: Large and Small Subunits Atom Soon
1285 The Ribosome's A, P, and E Sites Atom Soon
1287 tRNA Structure and the Anticodon Atom Soon
1289 Translation Initiation Atom Soon
1291 Translation Elongation Atom Soon
1293 Translation Termination Atom Soon
1295 Tracing One Gene from Transcription Through a Finished Protein Capstone Soon
1297 Point Mutations: Silent Atom Soon
1299 Point Mutations: Missense Atom Soon
1301 Point Mutations: Nonsense Atom Soon
1303 Frameshift Mutations Atom Soon
1305 "A DNA Mutation Is Always Harmful" Atom Soon
1307 Trinucleotide Repeat Expansions Atom Soon
1309 Causes of Mutation Atom Soon
1311 Levels of Gene-Expression Regulation, Overview Atom Soon
1313 Operon Structure Atom Soon
1315 The trp Operon: Repressible, Negative Regulation Atom Soon
1317 The lac Operon: Inducible Regulation Atom Soon
1319 Chromatin Packing as Gene Regulation Atom Soon
1321 Histone Modification Atom Soon
1323 DNA Methylation Atom Soon
1325 The Central Dogma's One-Way Information Flow, Restated Atom Soon
1327 "Traits Acquired in Life Are Inherited" Atom Soon
1329 Eukaryotic Transcription Factors and Enhancers Atom Soon
1331 Post-Transcriptional Regulation: Alternative Splicing Atom Soon
1333 Translational Regulation Atom Soon
1334 Post-Translational Regulation Atom Soon
1335 Gene Expression Is Regulated, Not Automatic Atom Soon
1337 "Genes Are Blueprints Executed Literally" Atom Soon
1339 Proto-Oncogenes and Oncogenes, Extended Atom Soon
1341 Tumor Suppressor Genes, Extended Atom Soon
1343 Tracing a Regulatory Failure from Mutated Gene to Unchecked Cell Division Capstone Soon
Unit 7

Biotechnology and Genomics

1521 Genomics Defined Atom Soon
1523 Gel Electrophoresis Atom Soon
1525 PCR: Amplifying a Target DNA Sequence Atom Soon
1527 RT-PCR: Amplifying from an RNA Template Atom Soon
1529 Southern and Northern Blotting Atom Soon
1531 Restriction Endonucleases and Sticky Ends Atom Soon
1533 The Plasmid Vector Atom Soon
1535 Constructing a Recombinant Plasmid Procedure Soon
1537 Recombinant Proteins Atom Soon
1539 Cellular Cloning Atom Soon
1541 Reproductive Cloning and Somatic Cell Nuclear Transfer Atom Soon
1543 "A Clone Is a Perfect Identical Copy" Atom Soon
1545 Genetic Engineering and Transgenic Organisms Atom Soon
1547 Gene Targeting and Reverse Genetics Atom Soon
1549 Recombinant Protein Production in Medicine Atom Soon
1551 Agrobacterium-Mediated Plant Transformation Atom Soon
1553 Bt Toxin as an Organic Insecticide Atom Soon
1555 Genetic Testing Atom Soon
1557 Gene Therapy Atom Soon
1559 The Physical Map Atom Soon
1561 Genetic Markers: RFLP, VNTR, and SNP Atom Soon
1563 Physical Mapping Methods: Cytogenetic, Radiation Hybrid, and Sequence Mapping Atom Soon
1565 Sequence-Tagged Sites Atom Soon
1567 Integrating Genetic and Physical Maps Atom Soon
1569 Sanger Chain-Termination Sequencing Atom Soon
1571 Shotgun Sequencing and Contigs Atom Soon
1573 Pairwise-End Sequencing Atom Soon
1575 Next-Generation Sequencing's Parallel Structure Atom Soon
1577 Whole-Genome versus Whole-Exome Sequencing Atom Soon
1579 Tracing Fragments to an Assembled, Annotated Genome Sequence Procedure Soon
1581 Sequence Alignment and BLAST Atom Soon
1583 Polygenic Disease Risk from Genome Analysis Atom Soon
1585 "A Genetic Risk Result Is a Diagnosis" Atom Soon
1587 Pharmacogenomics Atom Soon
1589 Metagenomics Atom Soon
1591 Mitochondrial Genomics Atom Soon
1593 Genomics in Agriculture Atom Soon
1595 The Proteome Atom Soon
1597 "The Genome Fully Predicts the Proteome" Atom Soon
1599 Techniques for Protein Analysis Atom Soon
1601 Systems Biology Atom Soon
1603 Metabolomics Atom Soon
1605 Tracing a Trait from a Sequenced Gene to Proteome-Level Function Capstone Soon
Unit 8

Evolutionary Processes

1641 Evolution Defined as Change in Allele Frequency Atom Soon
1643 Natural Selection Defined Atom Soon
1645 Darwin, Wallace, and the Path to 1859 Atom Soon
1647 Three Premises of Natural Selection Atom Soon
1649 Descent with Modification Atom Soon
1651 "Evolution Is Only a Theory" Atom Soon
1653 Scientific Theory, the Locked Term Reinforced Atom Soon
1655 Adaptation Defined Atom Soon
1657 Convergent and Divergent Evolution Atom Soon
1659 Homologous Structures Atom Soon
1661 Vestigial Structures Atom Soon
1663 Analogous Structures and Homoplasy Atom Soon
1665 Fossil Evidence for Evolution Atom Soon
1667 Comparative Embryology as Evidence Atom Soon
1669 Biogeography as Evidence Atom Soon
1671 Molecular Evidence: DNA Universality Atom Soon
1673 Genetic Variation from Mutation and Sexual Reproduction Atom Soon
1675 Neutral, Beneficial, and Deleterious Mutations Atom Soon
1677 "Organisms Evolve Because They Need To" Atom Soon
1679 Variation Precedes Selection Atom Soon
1681 "Humans Evolved from Monkeys" Atom Soon
1683 Common Ancestry, Not Common Descendant Atom Soon
1685 The Biological Species Concept Atom Soon
1687 Limits of the Biological Species Concept and Alternative Concepts Atom Soon
1689 The Gene Pool and Reproductive Isolation Atom Soon
1691 Speciation Defined Atom Soon
1693 Allopatric Speciation: Dispersal and Vicariance Atom Soon
1695 Adaptive Radiation Atom Soon
1697 Sympatric Speciation, Overview Atom Soon
1699 Polyploidy Atom Soon
1701 Autopolyploidy Atom Soon
1703 Alloploidy Atom Soon
1705 Nondisjunction as a Route to Polyploid Speciation Atom Soon
1707 Habitat and Behavioral Sympatric Speciation Atom Soon
1709 Prezygotic Reproductive Isolation, Overview Atom Soon
1711 Temporal Isolation Atom Soon
1713 Habitat Isolation Atom Soon
1715 Behavioral Isolation Atom Soon
1717 Mechanical Isolation Atom Soon
1719 Gametic Isolation Atom Soon
1721 Postzygotic Reproductive Isolation, Overview Atom Soon
1723 Hybrid Inviability and Hybrid Sterility Atom Soon
1725 Hybrid Breakdown Atom Soon
1727 Hybrid Zones Atom Soon
1729 Reinforcement, Fusion, and Stability Atom Soon
1731 Gradual Speciation and Punctuated Equilibrium Atom Soon
1733 Tracing One Allopatric Speciation Event Procedure Soon
1735 The Modern Synthesis Atom Soon
1737 Population Genetics Defined Atom Soon
1739 Allele Frequency Atom Soon
1741 Hardy-Weinberg Equilibrium Atom Soon
1743 Hardy-Weinberg's Five Assumptions Atom Soon
1745 The Hardy-Weinberg Equations Atom Soon
1747 Solving a Hardy-Weinberg Calculation Procedure Soon
1749 Polymorphism Atom Soon
1751 Heritability of Phenotypic Variation and Environmental Variation Atom Soon
1753 "Acquired Traits Are Inherited" Atom Soon
1755 Only Germline Variation Is Heritable Atom Soon
1757 Genetic Drift Atom Soon
1759 The Founder Effect Atom Soon
1761 The Bottleneck Effect Atom Soon
1763 Gene Flow and Clines Atom Soon
1765 Mutation as an Evolutionary Force, Population-Level Atom Soon
1767 Nonrandom Mating Atom Soon
1769 Fitness and Relative Fitness Atom Soon
1771 Stabilizing Selection Atom Soon
1773 Directional Selection Atom Soon
1775 Disruptive (Diversifying) Selection Atom Soon
1777 Frequency-Dependent Selection Atom Soon
1779 Sexual Selection and Sexual Dimorphism Atom Soon
1781 The Handicap Principle and the Good Genes Hypothesis Atom Soon
1783 Selection's Limits: No Perfect Organism, Not All Evolution Adaptive Atom Soon
1785 Tracing a Population's Adaptive Evolution from Mutation Through Fixation Capstone Soon
1787 Phylogeny Defined Atom Soon
1789 The Phylogenetic Tree as Hypothesis Atom Soon
1791 Rooted and Unrooted Trees Atom Soon
1793 Branch Points, Basal Taxa, Sister Taxa, and Polytomy Atom Soon
1795 Branch Length Does Not Default to Encoding Time Atom Soon
1797 The Linnaean Taxonomic Hierarchy Atom Soon
1799 Binomial Nomenclature Atom Soon
1801 Homology and Analogy, Applied to Phylogenetics Atom Soon
1803 Molecular Systematics Atom Soon
1805 Cladistics and Clades Atom Soon
1807 Monophyletic, Paraphyletic, and Polyphyletic Groups Atom Soon
1809 Shared Ancestral and Shared Derived Characters Atom Soon
1811 Maximum Parsimony Atom Soon
1813 Building a Phylogenetic Tree from Shared Derived Characters Procedure Soon
1815 Horizontal Gene Transfer, Defined Atom Soon
1817 HGT Mechanisms in Prokaryotes Atom Soon
1819 HGT in Eukaryotes Atom Soon
1821 Endosymbiosis, Revisited as Genome Fusion Atom Soon
1823 Competing Hypotheses for the Eukaryotic Nucleus's Origin Atom Soon
1825 The Web and Ring Models of Life Atom Soon
1827 Tracing Common-Descent Evidence Across One Clade Capstone Soon
1829 Prebiotic Earth Conditions and Abiotic Synthesis Atom Soon
1831 The Miller-Urey Experiment Atom Soon
1833 The RNA World Hypothesis Atom Soon
Unit 9

Microbial and Fungal Diversity

1901 Virion Structure: Genome, Capsid, and Envelope Atom Soon
1903 Four Capsid Shape Classes Atom Soon
1905 Viral Receptors and Host Specificity Atom Soon
1907 Viral Genome Types: DNA and RNA Atom Soon
1909 The Baltimore Classification Logic Atom Soon
1911 Baltimore Groups I–III Atom Soon
1913 Baltimore Groups IV–VII and Retroviruses Atom Soon
1915 Three Hypotheses for Viral Origin Atom Soon
1917 "A Virus Is a Living Organism" Atom Soon
1919 Whether a Virus Is Alive, Revisited Atom Soon
1921 Steps of Viral Replication, Overview Atom Soon
1923 The Lytic Cycle Atom Soon
1925 The Lysogenic Cycle and Latency Atom Soon
1927 Plant Virus Transmission Atom Soon
1929 Animal Virus Entry and Exit Atom Soon
1931 Oncogenic Viruses Atom Soon
1933 Vaccines: Mechanism of Protection Atom Soon
1935 Antiviral Drug Mechanism Atom Soon
1937 Combination Therapy Against a Fast-Mutating Virus Atom Soon
1938 Subviral Agents: Prions and Viroids Atom Soon
1939 Tracing a Viral Infection from Attachment Through Immune Clearance and Treatment Capstone Soon
1941 Prokaryotic Cell Structure, Reused and Extended Atom Soon
1943 Three Prokaryotic Cell Shapes Atom Soon
1945 Bacteria versus Archaea: Membrane Lipid Differences Atom Soon
1947 The Peptidoglycan Cell Wall and the Gram Stain Atom Soon
1949 Gram-Positive versus Gram-Negative Wall Structure Atom Soon
1951 Archaeal Cell Walls Atom Soon
1953 Species Delimitation: Ribosomal RNA Sequencing Atom Soon
1955 Binary Fission and Horizontal Gene Transfer, Reused Atom Soon
1957 The Four Prokaryotic Nutritional Categories Atom Soon
1959 Prokaryotes and the Carbon Cycle Atom Soon
1961 Prokaryotes and the Nitrogen Cycle Atom Soon
1963 Extremophiles and Biofilms Atom Soon
1965 Bacterial Disease Mechanism, Overview Atom Soon
1967 Antibiotic Resistance Mechanism Atom Soon
1969 Nitrogen-Fixation Mutualism Atom Soon
1971 The Human Microbiome Atom Soon
1973 "Germs Are All Bad" Atom Soon
1975 Beneficial Prokaryotes, Correctly Weighted Atom Soon
1977 Bioremediation Atom Soon
1979 Classifying a Prokaryote by Its Nutritional Category Procedure Soon
1981 "Protist" as a Paraphyletic Wastebasket Grouping Atom Soon
1983 Eukaryotic Characteristics of the Last Common Ancestor Atom Soon
1985 Endosymbiosis Among Protists, Revisited Atom Soon
1987 Secondary Endosymbiosis Atom Soon
1989 Protist Cell Structure and Metabolic Diversity Atom Soon
1991 Protist Motility Atom Soon
1993 Protist Life Cycles Atom Soon
1995 The Five-Supergroup Classification Criterion Atom Soon
1997 Archaeplastida Atom Soon
1999 Amoebozoa and Slime Molds Atom Soon
2001 Opisthokonta and Choanoflagellates Atom Soon
2003 The SAR Supergroup: Stramenopiles, Alveolates, and Rhizaria Atom Soon
2005 Alveolates: Dinoflagellates and Ciliates Atom Soon
2007 Apicomplexans and Malaria Mechanism Atom Soon
2009 Stramenopiles: Diatoms and Brown Algae Atom Soon
2011 Rhizaria: Forams and Radiolarians Atom Soon
2013 Excavata Atom Soon
2015 Excavate Parasites: Giardia and Trypanosomes Atom Soon
2017 Protist Ecology: Producers, Decomposers, and Symbionts Atom Soon
2019 Classifying an Unfamiliar Protist by Supergroup-Defining Criteria Procedure Soon
2021 Tracing a Protist Lineage's Endosymbiotic Origin and Ecological Role Capstone Soon
2023 Fungal Characteristics: Heterotrophic Absorption and the Chitin Wall Atom Soon
2025 Hyphae and Mycelium Atom Soon
2027 Septate versus Coenocytic Hyphae Atom Soon
2029 Yeast: The Unicellular Fungal Form Atom Soon
2031 Asexual Fungal Reproduction Atom Soon
2033 Sexual Fungal Reproduction: Plasmogamy, Karyogamy, and Meiosis Atom Soon
2035 Fungal Classification: Reproductive Structure as the Criterion Atom Soon
2037 Chytridiomycota Atom Soon
2039 Zygomycota Atom Soon
2041 Glomeromycota Atom Soon
2043 Ascomycota Atom Soon
2045 Basidiomycota Atom Soon
2047 "Mold and Mushroom Are Unrelated Organisms" Atom Soon
2049 Growth Form versus Taxonomic Group Atom Soon
2051 Fungal Ecology: Decomposers and Nutrient Cycling Atom Soon
2053 Mycorrhizae Mechanism Atom Soon
2055 Lichens Atom Soon
2057 Fungal Plant Pathogens Atom Soon
2059 Fungal Human Pathogens: Mycosis Categories Atom Soon
2061 Antifungal Treatment Difficulty Atom Soon
2063 Fermentation and Food Uses of Fungi Atom Soon
2065 Fungi as Medical Compound Sources Atom Soon
2067 Fungi as Genetic Model Organisms Atom Soon
2069 Tracing a Mycorrhizal Symbiosis from Colonization Through Ecosystem Effect Capstone Soon
Unit 10

Plant and Animal Diversity

2161 Land Plant Origin Among the Charophyte Green Algae Atom Soon
2163 Four Adaptations for Life on Land Atom Soon
2165 The Haplodiplontic Life Cycle in Land Plants Atom Soon
2167 "Seaweed Is a Plant" Atom Soon
2169 Algae versus Land Plants, the Defining Line Atom Soon
2171 Bryophyte Defining Traits: Nonvascular, Gametophyte-Dominant Atom Soon
2173 Bryophyte Diversity: Liverworts, Mosses, and Hornworts Atom Soon
2175 Moss Life Cycle, Worked Procedure Soon
2177 Seedless Vascular Plant Traits: Vascular Tissue, Sporophyte Dominance Atom Soon
2179 Lycophytes versus Monilophytes Atom Soon
2181 Homospory versus Heterospory Atom Soon
2183 Carboniferous Coal Forests Atom Soon
2185 Seed Evolution: Three Key Innovations Atom Soon
2187 Advantages of a Seed over a Spore Atom Soon
2189 Gymnosperm Defining Trait: the Naked Seed Atom Soon
2191 Four Gymnosperm Phyla Atom Soon
2193 Conifer Life Cycle Basics Atom Soon
2195 Angiosperm Defining Traits: Flower and Fruit Atom Soon
2197 Flower Structure Atom Soon
2199 Double Fertilization Mechanism Atom Soon
2201 Monocots versus Eudicots Atom Soon
2203 Angiosperm-Pollinator Coevolution Atom Soon
2205 Fruit Types and Seed Dispersal Atom Soon
2207 Ecological and Economic Role of Seed Plants Atom Soon
2209 Classifying a Plant Sample by Vascular, Seed, and Flower Criteria Procedure Soon
2211 Tracing One Lineage from Charophyte Ancestor to Angiosperm Flower Capstone Soon
2213 Animal Kingdom Defining Features Atom Soon
2215 Embryonic Development: Blastula and Gastrulation Atom Soon
2217 Diploblastic versus Triploblastic Body Plans Atom Soon
2219 Body Symmetry: Asymmetry, Radial, Bilateral Atom Soon
2221 Cephalization Atom Soon
2223 Coelom Types: Acoelomate, Pseudocoelomate, Coelomate Atom Soon
2225 Protostome versus Deuterostome Development Atom Soon
2227 "Plants Are Simpler Than Animals" Atom Soon
2229 Evolutionary Complexity Has No Direction Atom Soon
2231 Animal Phylogeny as Evidence-Based and Revisable Atom Soon
2233 Sponges' Contested Position at the Animal Root Atom Soon
2235 The Cambrian Explosion Atom Soon
2237 Phylum Porifera: Body Structure without True Tissues Atom Soon
2239 "Sponges Aren't Really Animals" Atom Soon
2241 Choanocytes and Positive Evidence for Sponge Ancestry Atom Soon
2243 Cnidarian Body Plan: Polyp and Medusa Atom Soon
2245 Cnidocytes and Nematocysts Atom Soon
2247 Four Cnidarian Classes Atom Soon
2249 Lophotrochozoa Defined Atom Soon
2251 Phylum Platyhelminthes: Flatworms Atom Soon
2253 Phylum Rotifera Atom Soon
2255 Phylum Nemertea: Ribbon Worms Atom Soon
2257 Mollusk Body Plan: Foot, Mantle, Visceral Mass Atom Soon
2259 Three Major Mollusk Classes Atom Soon
2261 Annelid Segmentation Atom Soon
2263 Ecdysozoa Defined: the Molting Cuticle Atom Soon
2265 Phylum Nematoda Atom Soon
2267 Phylum Tardigrada Atom Soon
2269 Arthropod Defining Traits Atom Soon
2271 Four Arthropod Subphyla Atom Soon
2273 "An Insect and a Spider Are Both Bugs" Atom Soon
2275 Insects versus Arachnids, Structurally Distinguished Atom Soon
2277 Deuterostomia Defined Atom Soon
2279 Echinoderm Body Plan: Water Vascular System Atom Soon
2281 Phylum Hemichordata Atom Soon
2283 Classifying an Unfamiliar Invertebrate by Body-Plan Criteria Procedure Soon
2285 Tracing the Protostome-Deuterostome Branch Point Capstone Soon
2287 Chordate Defining Traits Atom Soon
2289 Subphylum Vertebrata: the Vertebral Column Atom Soon
2291 Jawless versus Jawed Fishes Atom Soon
2293 Cartilaginous versus Bony Fishes Atom Soon
2295 Amphibian Traits: Dual Life and Permeable Skin Atom Soon
2297 Reptile Traits: the Amniotic Egg Atom Soon
2299 Birds as a Clade Nested within Reptilia Atom Soon
2301 Bird Flight Adaptations Atom Soon
2303 Mammal Traits: Hair and Mammary Glands Atom Soon
2305 Three Living Mammal Clades Atom Soon
2307 Primate Traits Atom Soon
2309 Human Lineage: Hominins, Not a Line Atom Soon
2311 "Humans Are the Most Evolved Animal" Atom Soon
2313 Evolution Has No Endpoint or Direction Atom Soon
2315 Tracing Tetrapod Evolution from Lobe-Finned Fish to Amniotes Capstone Soon
Unit 11

Plant Structure and Function

2501 Plant Organ Systems: Shoot and Root Atom Soon
2503 Meristematic versus Permanent Tissue Atom Soon
2505 Three Meristem Locations: Apical, Lateral, Intercalary Atom Soon
2507 Dermal, Vascular, and Ground Tissue Atom Soon
2509 Simple versus Complex Tissue: Xylem and Phloem Atom Soon
2511 Stem Anatomy: Parenchyma, Collenchyma, Sclerenchyma Atom Soon
2513 Primary Growth: Apical Meristem Elongation Atom Soon
2515 "A Tree Grows Taller by Pushing Up From the Base" Atom Soon
2517 Why a Nail in a Trunk Never Rises Atom Soon
2519 Apical Dominance Atom Soon
2521 Secondary Growth: Vascular Cambium and Cork Cambium Atom Soon
2523 Annual Rings Atom Soon
2525 Stem Modifications Atom Soon
2527 Taproot versus Fibrous Root Systems Atom Soon
2529 Root Growth Zones Atom Soon
2531 Root Anatomy: Endodermis and Casparian Strip Atom Soon
2533 Root Modifications Atom Soon
2535 Leaf Structure: Mesophyll, Stomata, Veins Atom Soon
2537 Simple versus Compound Leaves Atom Soon
2539 Leaf Arrangement: Phyllotaxy Atom Soon
2541 Water Potential: Solute, Pressure, Gravity, Matric Components Atom Soon
2543 Cohesion-Tension Theory of Sap Ascent Atom Soon
2545 Transpiration and Stomatal Regulation Atom Soon
2547 Translocation: Pressure-Flow in Phloem Atom Soon
2549 Tracing Water and Photosynthate Transport, Worked Procedure Soon
2551 Phototropism: the Phytochrome and Blue-Light Systems Atom Soon
2553 Photoperiodism Atom Soon
2555 Gravitropism Atom Soon
2557 Thigmotropism and Thigmonasty Atom Soon
2559 Auxin Atom Soon
2561 The Darwin and Boysen-Jensen Phototropism Experiments, Worked Procedure Soon
2563 Cytokinins Atom Soon
2565 Gibberellins Atom Soon
2567 Ethylene Atom Soon
2569 Abscisic Acid Atom Soon
2571 Tracing Apical Dominance Through Auxin-Cytokinin Balance, Worked Capstone Capstone Soon
2573 Essential Nutrients: Macronutrients and Micronutrients Atom Soon
2575 Deficiency Symptoms as Diagnostic Method Atom Soon
2577 Soil Composition: Four Major Components Atom Soon
2579 Soil Horizons: O, A, B, C Atom Soon
2581 "Plants Get Most of Their Mass From the Soil" Atom Soon
2583 Photosynthesis Supplies a Plant's Mass, Not Soil Atom Soon
2585 Nitrogen Fixation and the Legume-Rhizobia Symbiosis Atom Soon
2587 Ectomycorrhizae and Endomycorrhizae Atom Soon
2589 Parasitic Plants: Holoparasites and Hemiparasites Atom Soon
2591 Carnivorous Plants as a Nutrient Adaptation Atom Soon
2593 "Carnivorous Plants Eat Insects Instead of Photosynthesizing" Atom Soon
2595 Insect Prey Supplements Nitrogen, Not Energy Atom Soon
2597 Epiphytes Atom Soon
2599 Classifying a Plant's Nutritional Strategy, Worked Procedure Soon
2601 Male Gametophyte Development: Microsporogenesis and the Pollen Grain Atom Soon
2603 Female Gametophyte Development: Megasporogenesis and the Embryo Sac Atom Soon
2605 Complete versus Incomplete Flowers Atom Soon
2606 Monoecious versus Dioecious Species Atom Soon
2607 Pollination Mechanisms and Pollinator Syndromes Atom Soon
2609 Self-Pollination versus Cross-Pollination Atom Soon
2611 Self-Incompatibility Mechanisms Atom Soon
2613 "Self-Pollination and Asexual Reproduction Are the Same Thing" Atom Soon
2615 Self-Pollination Still Requires Meiosis and Fertilization Atom Soon
2617 Double Fertilization Detail: Endosperm and Seed Coat Development Atom Soon
2619 Seed Structure and Monocot/Dicot Storage Strategy Atom Soon
2621 Seed Dormancy and Germination Cues Atom Soon
2623 Fruit Types Revisited: Simple, Aggregate, Multiple, Accessory Atom Soon
2625 Asexual/Vegetative Reproduction: Natural Methods Atom Soon
2627 Asexual/Vegetative Reproduction: Artificial Methods Atom Soon
2629 Evolutionary Tradeoffs: Sexual versus Asexual Reproduction Atom Soon
2631 Plant Life Spans and Flowering Frequency Atom Soon
2633 Tracing a Flower From Pollination to Seed Dispersal, Worked Capstone Capstone Soon
Unit 12

Animal Form, Nutrition, and Control Systems

2721 Body Plans and the Symmetry Constraint Atom Soon
2723 Body Planes Atom Soon
2724 Body Cavities: Dorsal and Ventral Atom Soon
2725 Exoskeleton and Endoskeleton Size Limits Atom Soon
2727 Surface-to-Volume Ratio Limits Size Atom Soon
2729 Endotherms and Ectotherms Atom Soon
2731 Metabolic Rate: BMR and SMR Atom Soon
2733 Torpor, Hibernation, and Estivation Atom Soon
2735 Four Primary Animal Tissue Types Atom Soon
2737 Epithelial Tissue: Simple and Stratified Atom Soon
2739 Connective Tissue: Matrix and Fiber Types Atom Soon
2741 Bone Remodeling: Osteoblasts, Osteocytes, Osteoclasts Atom Soon
2743 Three Muscle Tissue Types Atom Soon
2745 Nervous Tissue: Neurons and Glia, Introduced Atom Soon
2747 The Set Point and Feedback Control Atom Soon
2749 Negative Feedback Loop Atom Soon
2751 Positive Feedback Loop Atom Soon
2753 "Positive Feedback Means Something Has Gone Wrong" Atom Soon
2755 Positive Feedback Is Self-Limiting by Design Atom Soon
2757 Thermoregulation: Four Heat-Exchange Mechanisms Atom Soon
2758 Thermoregulatory Responses: Insulation, Vasodilation, Vasoconstriction, Behavior Atom Soon
2759 Classifying an Animal's Thermoregulatory Strategy, Worked Procedure Soon
2763 Herbivore, Carnivore, Omnivore Diet Classification Atom Soon
2765 Gastrovascular Cavity versus Alimentary Canal Atom Soon
2767 Monogastric versus Ruminant Digestive Systems Atom Soon
2769 Avian Digestive Adaptations Atom Soon
2771 Oral Cavity: Mastication and Salivary Enzymes Atom Soon
2773 Esophagus and Peristalsis Atom Soon
2775 Stomach: Acid Environment and Pepsin Atom Soon
2777 Small Intestine: Villi and Microvilli Atom Soon
2779 Duodenum, Jejunum, Ileum Atom Soon
2781 Large Intestine: Water Reabsorption Atom Soon
2783 Accessory Organs: Liver, Pancreas, Gallbladder Atom Soon
2785 Essential Nutrients Atom Soon
2787 Macronutrient Caloric Density Atom Soon
2789 Four-Step Nutritional Process: Ingestion to Elimination Atom Soon
2791 Carbohydrate Digestion Atom Soon
2793 Protein Digestion Atom Soon
2795 Lipid Digestion: Emulsification Atom Soon
2797 Glycogen Storage and Mobilization Atom Soon
2799 Neural Control: Three Digestive Phases Atom Soon
2801 Hormonal Control: Gastrin, Secretin, CCK Atom Soon
2803 "Skipping a Meal Immediately Starves the Body" Atom Soon
2805 Glycogen Reserves Buffer Short-Term Fasting Atom Soon
2807 Obesity as an Energy-Balance Imbalance Atom Soon
2809 Eating Disorders as Disrupted Energy-Intake Regulation Atom Soon
2811 Tracing a Meal Through the Digestive Tract, Worked Capstone Soon
2815 Neuron Structure: Dendrites, Soma, Axon Atom Soon
2817 Four Neuron Types Atom Soon
2819 Glial Cell Types Atom Soon
2821 Resting Membrane Potential Atom Soon
2823 Action Potential Atom Soon
2825 Myelin and Saltatory Conduction Atom Soon
2827 Chemical Synapse: Neurotransmitter Release Atom Soon
2829 Electrical Synapse: Gap Junctions Atom Soon
2831 EPSP, IPSP, and Summation Atom Soon
2833 Long-Term Potentiation and Long-Term Depression Atom Soon
2835 "Addiction Is a Failure of Willpower" Atom Soon
2837 Addiction as Hijacked Synaptic Plasticity Atom Soon
2839 Meninges and Cerebrospinal Fluid Atom Soon
2841 Cerebral Cortex: Hemispheres and Lobes Atom Soon
2843 Frontal, Parietal, Occipital, Temporal Lobe Functions Atom Soon
2845 Basal Ganglia, Thalamus, and Hypothalamus Atom Soon
2847 Limbic System and the Amygdala Atom Soon
2849 Cerebellum and Brainstem Atom Soon
2851 Spinal Cord: Gray and White Matter Atom Soon
2853 The Spinal Reflex Arc Atom Soon
2855 Autonomic Nervous System: Two-Synapse Relay Atom Soon
2857 Sympathetic Nervous System Atom Soon
2859 Parasympathetic Nervous System Atom Soon
2861 Sensory-Somatic Nervous System Atom Soon
2863 Neurodegenerative Disorders as Neuron Loss Atom Soon
2865 Neurodevelopmental Disorders as Atypical Wiring Atom Soon
2867 Tracing a Reflex Arc Signal Path, Worked Procedure Soon
2871 Sensory Transduction Atom Soon
2873 Receptive Field and Receptor Specificity Atom Soon
2875 Sensation versus Perception Atom Soon
2877 Stimulus Intensity Encoding Atom Soon
2879 Somatosensory Mechanoreceptors Atom Soon
2881 Two-Point Discrimination and Receptor Density Atom Soon
2883 Thermoreception Atom Soon
2885 Nociception and the Subjectivity of Pain Atom Soon
2887 Taste: Five Primary Tastants Atom Soon
2889 Olfaction: Receptor Diversity and Odor Coding Atom Soon
2891 "Humans Have Only Five Senses" Atom Soon
2893 Somatosensation Splits Into Several Distinct Modalities Atom Soon
2895 Sound Wave Properties: Frequency and Amplitude Atom Soon
2897 Outer and Middle Ear: Ossicle Amplification Atom Soon
2899 Cochlea and the Organ of Corti Atom Soon
2901 Place Theory of Pitch Perception Atom Soon
2903 Vestibular System: Utricle, Saccule, Semicircular Canals Atom Soon
2905 Eye Anatomy: Cornea, Lens, Iris Atom Soon
2907 Rods versus Cones Atom Soon
2909 Phototransduction: Rhodopsin and Hyperpolarization Atom Soon
2911 Trichromatic Color Coding Atom Soon
2913 Retinal Processing: Lateral Inhibition Atom Soon
2915 Tracing a Sound Wave From Air to Auditory Cortex, Worked Procedure Soon
2919 Three Hormone Chemical Classes Atom Soon
2921 Lipid-Soluble versus Water-Soluble Receptor Location Atom Soon
2923 Intracellular Hormone Receptors and Gene Transcription Atom Soon
2925 Plasma Membrane Receptors and cAMP Second Messenger Atom Soon
2927 "Hormones and Neurotransmitters Are Entirely Different Things" Atom Soon
2929 One Molecule Can Signal as Both Hormone and Neurotransmitter Atom Soon
2931 Hypothalamic-Pituitary Axis Atom Soon
2933 Anterior versus Posterior Pituitary Atom Soon
2935 ADH and Water Balance Atom Soon
2937 Aldosterone and the Renin-Angiotensin-Aldosterone System Atom Soon
2939 Thyroid Hormones and Metabolic Rate Atom Soon
2941 Parathyroid Hormone and Calcitonin: Opposing Calcium Control Atom Soon
2943 Insulin and Glucagon: Opposing Glucose Control Atom Soon
2945 Growth Hormone: Direct and Indirect Mechanisms Atom Soon
2947 Adrenal Cortex versus Adrenal Medulla Atom Soon
2949 Short-Term versus Long-Term Stress Response Atom Soon
2951 Negative Feedback in Hormone Regulation Atom Soon
2953 Three Stimuli Triggering Hormone Release Atom Soon
2955 Gonadal Hormones and Reproductive Regulation Atom Soon
2957 "Steroid Hormones Are Only a Bodybuilding Drug" Atom Soon
2959 Anabolic Steroids Disrupt the Body's Own Endocrine Feedback Atom Soon
2961 Endocrine Glands With Secondary Function Atom Soon
2963 Tracing the Hypothalamic-Pituitary-Thyroid Feedback Loop, Worked Procedure Soon
2965 Tracing a Stress Response From Stimulus to Hormone Cascade, Worked Capstone Capstone Soon
Unit 13

Animal Support, Transport, Defense, and Reproduction

3081 Hydrostatic Skeleton Mechanism Atom Soon
3083 Exoskeleton Structure and Molting Atom Soon
3085 Endoskeleton Structure Overview Atom Soon
3087 Axial Skeleton Atom Soon
3089 Appendicular Skeleton Atom Soon
3091 Bone Classification by Shape Atom Soon
3093 Compact versus Spongy Bone Atom Soon
3095 Bone Marrow: Red and Yellow Atom Soon
3097 Bone Growth: Ossification and the Epiphyseal Plate Atom Soon
3099 Cartilage Types Atom Soon
3101 Tendons versus Ligaments Atom Soon
3103 Fibrous Joints Atom Soon
3105 Cartilaginous Joints Atom Soon
3107 Synovial Joints and Synovial Fluid Atom Soon
3109 Synovial Movement Types Atom Soon
3111 Skeletal Muscle Organization: Fascicle to Sarcomere Atom Soon
3113 Sarcomere Structure Atom Soon
3115 Sliding Filament Mechanism Atom Soon
3117 Neuromuscular Junction and Excitation-Contraction Coupling Atom Soon
3119 Calcium, Troponin, and Tropomyosin Atom Soon
3121 ATP's Three Roles in Muscle Contraction Atom Soon
3123 Slow-Twitch and Fast-Twitch Muscle Fibers Atom Soon
3125 "Muscles Only Pull, Never Push" Atom Soon
3127 Antagonistic Muscle Pairs Produce Both Directions of Movement Atom Soon
3131 Tracing a Single Muscle Contraction Cycle, Worked Procedure Soon
3141 Partial Pressure and the Diffusion Gradient Atom Soon
3143 Gas Exchange Surface Requirements Atom Soon
3145 Integumentary Gas Exchange Atom Soon
3147 Gills and Countercurrent Exchange Atom Soon
3149 Tracheal System in Insects Atom Soon
3151 Mammalian Lung Structure Atom Soon
3153 Avian Flow-Through Lungs and Air Sacs Atom Soon
3155 Negative-Pressure Breathing Mechanics Atom Soon
3157 Compliance and Resistance in the Lungs Atom Soon
3159 V/Q Mismatch Mechanism Atom Soon
3161 Hemoglobin Structure and Cooperative Binding Atom Soon
3163 The Oxygen-Hemoglobin Dissociation Curve Atom Soon
3165 The Bohr Effect Atom Soon
3167 CO2 Transport: Bicarbonate and Carbaminohemoglobin Atom Soon
3169 "Breathing Is Driven by Low Oxygen" Atom Soon
3171 Rising CO2 and Falling pH Drive the Breathing Reflex Atom Soon
3175 Tracing Gas Exchange Across the Pulmonary-Systemic Loop, Worked Procedure Soon
3185 Open versus Closed Circulatory Systems Atom Soon
3187 Single versus Double Circulation Atom Soon
3189 Blood Plasma Composition Atom Soon
3191 Erythrocyte Structure and Function Atom Soon
3193 Leukocyte Types, Introduced Atom Soon
3195 Platelets and the Clotting Cascade Atom Soon
3197 Heart Chambers and Valves Atom Soon
3199 Cardiac Cycle: Systole and Diastole Atom Soon
3201 SA Node and the Cardiac Conduction System Atom Soon
3203 Artery Structure Atom Soon
3205 Vein Structure Atom Soon
3207 Capillary Structure and Exchange Atom Soon
3209 "Arteries Carry Oxygenated Blood, Veins Carry Deoxygenated Blood" Atom Soon
3211 Vessel Direction, Not Oxygen Content, Defines Artery and Vein Atom Soon
3215 Baroreceptor Reflex and Blood Pressure Regulation Atom Soon
3217 The Lymphatic System's Role Alongside Circulation Atom Soon
3221 Tracing Blood Through Double Circulation, Worked Procedure Soon
3231 Osmoconformers versus Osmoregulators Atom Soon
3233 Osmotic Balance Challenges by Habitat Atom Soon
3235 Nephron Structure Atom Soon
3237 Filtration, Reabsorption, Secretion: the Three-Step Mechanism Atom Soon
3239 The Loop of Henle and the Countercurrent Multiplier Atom Soon
3241 ADH and Aquaporin Insertion in the Collecting Duct Atom Soon
3243 Excretory Organs Across Taxa: Flame Cells, Malpighian Tubules, Nephridia Atom Soon
3245 Nitrogenous Waste Forms and Tradeoffs Atom Soon
3249 Tracing Filtrate Through the Nephron, Worked Procedure Soon
3259 Innate Immunity: Physical and Chemical Barriers Atom Soon
3261 Phagocytes: Neutrophils and Macrophages Atom Soon
3263 Inflammation Mechanism Atom Soon
3265 Fever as a Systemic Innate Response Atom Soon
3267 The Complement System Atom Soon
3269 Interferons and Viral Defense Atom Soon
3271 Natural Killer Cells Atom Soon
3273 Adaptive Immunity: Humoral versus Cell-Mediated Atom Soon
3275 Antigen Specificity and Receptor Diversity Atom Soon
3277 B Cell Activation and Clonal Selection Atom Soon
3279 T Cell Types: Helper and Cytotoxic Atom Soon
3281 MHC Class I and II Antigen Presentation Atom Soon
3283 Antibody Structure Atom Soon
3285 Antibody Classes and Functions Atom Soon
3287 Immunological Memory Atom Soon
3289 "Vaccines Give You the Disease" Atom Soon
3291 A Vaccine Trains Memory Without Causing Disease Atom Soon
3295 "Antibiotics Work on Viruses" Atom Soon
3297 Antibiotics Target Bacterial Structures a Virus Lacks Atom Soon
3301 Autoimmune Disease Mechanism Atom Soon
3303 Immunodeficiency Mechanism Atom Soon
3305 Hypersensitivity and Allergy Mechanism Atom Soon
3307 Cancer Immune Evasion Mechanism Atom Soon
3311 Tracing the Innate Response to a Skin Wound, Worked Procedure Soon
3321 Asexual Reproduction Methods Atom Soon
3323 Sexual Reproduction's Genetic-Diversity Advantage Atom Soon
3325 External versus Internal Fertilization Atom Soon
3327 Oviparity, Ovoviviparity, Viviparity Atom Soon
3329 Male Reproductive Anatomy Atom Soon
3331 Female Reproductive Anatomy Atom Soon
3333 Spermatogenesis Mechanism Atom Soon
3335 Oogenesis Mechanism Atom Soon
3337 The HPG Axis and Hormonal Control of Male Reproduction Atom Soon
3339 Hormonal Control of the Menstrual Cycle Atom Soon
3341 "Fertilization Takes Many Sperm to Break Through the Egg" Atom Soon
3343 One Sperm Fertilizes the Egg; Polyspermy Is Actively Blocked Atom Soon
3347 Placenta Structure and Function Atom Soon
3349 Human Gestation: a Structural Mechanism Atom Soon
3351 Hormonal Signaling for Labor Atom Soon
3353 Cleavage and Blastula Formation Atom Soon
3355 Gastrulation and the Three Germ Layers Atom Soon
3357 Organogenesis Overview Atom Soon
3359 Vertebrate Axis Formation Atom Soon
3361 "Identical Twins Are 100% Genetically Identical" Atom Soon
3363 Somatic Mutation Breaks Perfect Genetic Identity After Twinning Atom Soon
3367 Tracing Fertilization Through Early Embryonic Development, Worked Procedure Soon
3369 Determination and Differentiation Atom Soon
3371 Induction and Morphogen Gradients Atom Soon
3373 Hox Genes and Body-Plan Specification Atom Soon
3375 Stem Cell Potency Atom Soon
3401 Tracing Fluid, Gas, and Waste Balance During Exercise, Worked Capstone Capstone Soon
Unit 14

Ecology, Ecosystems, and Conservation

3481 Ecology's Levels of Organization Atom Soon
3483 Biogeography and Abiotic Distribution Factors Atom Soon
3485 Endemic versus Generalist Species Atom Soon
3489 Light and Nutrient Availability Across Habitats Atom Soon
3491 Temperature as a Distribution Constraint Atom Soon
3493 Biome Definition and Classification Basis Atom Soon
3495 Desert and Tropical Wet Forest Contrast Atom Soon
3497 Grassland and the Role of Fire Disturbance Atom Soon
3499 Tundra and the Permafrost Constraint Atom Soon
3501 Aquatic Biome Classification by Salinity and Zone Atom Soon
3505 Classifying a Biome from Climate and Vegetation Data, Worked Procedure Soon
3521 The Greenhouse Effect Mechanism Atom Soon
3523 How Atmospheric Greenhouse-Gas Concentration Is Measured Atom Soon
3525 How Global Mean Temperature Change Is Measured and Reported Atom Soon
3541 Population Size and Population Density Atom Soon
3545 Quadrat and Mark-Recapture Sampling Methods Atom Soon
3547 Uniform, Random, and Clumped Dispersion Patterns Atom Soon
3549 Life Tables and Age-Specific Mortality Atom Soon
3553 The Three Survivorship Curve Types Atom Soon
3555 Life History Strategy Shaped by Natural Selection Atom Soon
3557 Exponential Population Growth Atom Soon
3559 Logistic Growth and Carrying Capacity Atom Soon
3563 Density-Dependent Limiting Factors Atom Soon
3565 Density-Independent Limiting Factors Atom Soon
3569 Human Population Growth as a Case of the Same Models Atom Soon
3573 Tracing a Population from Exponential Onset Through Logistic Leveling, Worked Procedure Soon
3591 Community Interactions: Competition Atom Soon
3593 Predation and Herbivory Atom Soon
3595 Symbiosis: Mutualism, Commensalism, and Parasitism Atom Soon
3599 "Any Close Species Relationship Is Parasitic" Atom Soon
3601 Fitness Outcome, Not Closeness Alone, Classifies a Symbiosis Atom Soon
3605 Competitive Exclusion and the Ecological Niche Atom Soon
3607 Resource Partitioning Atom Soon
3609 Primary and Secondary Ecological Succession Atom Soon
3613 Pioneer Species and Facilitation Atom Soon
3615 Proximate versus Ultimate Causation in Behavior Atom Soon
3617 Interpreting a Population Change Through Community Interactions, Worked Procedure Soon
3619 Innate Behavior and Fixed Action Patterns Atom Soon
3621 Habituation Atom Soon
3623 Imprinting Atom Soon
3625 Classical Conditioning Atom Soon
3627 Operant Conditioning Atom Soon
3629 Foraging and Optimality Atom Soon
3631 Communication and Pheromones Atom Soon
3633 Mating Systems Atom Soon
3635 Eusociality and Kin Selection Atom Soon
3641 Trophic Levels and Food Chains Atom Soon
3645 Food Webs versus Food Chains Atom Soon
3649 Energy Flow and the Ten-Percent Rule Atom Soon
3653 "Ecosystems Recycle Their Energy the Way They Recycle Matter" Atom Soon
3655 Biogeochemical Cycling Applies to Matter, Not Energy Atom Soon
3659 The Carbon Cycle Atom Soon
3663 The Nitrogen Cycle Atom Soon
3667 The Phosphorus Cycle Atom Soon
3671 The Water Cycle Atom Soon
3675 Tracing Energy Loss and Nutrient Cycling Through a Food Chain, Worked Procedure Soon
3677 Keystone Species Atom Soon
3681 Defensive Adaptations and Mimicry Atom Soon
3685 Character Displacement Atom Soon
3689 Gross and Net Primary Productivity and Ecological Pyramids Atom Soon
3693 Eutrophication and Acid Rain as Nutrient-Cycle Disruptions Atom Soon
3701 Species Richness and Species Diversity Atom Soon
3705 Background Extinction Rate versus Mass Extinction Atom Soon
3709 How the IUCN Red List Classifies Extinction Risk Atom Soon
3713 How an Extinction-Risk Assessment Is Constructed Atom Soon
3717 Instrumental Value of Biodiversity Atom Soon
3721 Intrinsic Value of Biodiversity Atom Soon
3725 Applying Red List Criteria to Classify a Described Species, Worked Procedure Soon
3741 Habitat Loss and Fragmentation Atom Soon
3745 Invasive Species Atom Soon
3749 Overexploitation Atom Soon
3753 Climate Change as a Biodiversity Threat Atom Soon
3757 In Situ Conservation: Protected Areas Atom Soon
3761 Ex Situ Conservation: Captive Breeding and Seed Banks Atom Soon
3765 "An Extinct Species Can Be Fully Restored" Atom Soon
3767 De-Extinction Restores Genome, Not the Original Ecological Context Atom Soon
3771 Conservation Status Is a Reassessed Classification, Not a Fixed Fact Atom Soon
3775 "A Species' Conservation Status Never Changes Once Assigned" Atom Soon
3781 Applying Threat Categories and Conservation Strategy to a Described Case, Worked Procedure Soon
3891 Tracing a Species from Population Decline to Conservation Response, Worked Capstone Capstone Soon

The receipts

Check my work.

Behind the course sits a reference document in which every definition and mechanism is traced to its source. The anchor is an openly licensed university text — OpenStax’s Biology 2e — read against an independently authored second text so that where the two differ, the difference is noted rather than smoothed over. The experiments that settled a question are cited to the papers that ran them: Griffith, Avery, Hershey and Chase, Franklin and Gosling, Watson and Crick, Meselson and Stahl.

Where a question is genuinely open — whether a virus is alive, the relative weight of drift against selection — the course says so and presents the competing positions instead of picking one. Where a topic touches human health, the video carries an on-screen note that it is educational content and not medical advice.

This is outside my own teaching fields — philosophy, logic, and ethics — so the sourcing carries more of the weight than the résumé does. That is the point of publishing it. Spot an error? Tell me the video number and the claim — corrections get made in the open.

Follow along

New videos daily.

The course releases in order on YouTube — one idea at a time until all 1133 are live. Subscribe to catch each one, or leave your email for an occasional note when a course finishes.