All courses · core course
Genetics and Molecular Biology
A core course for biology majors and premedical students. It starts with Mendel and the logic of crosses, follows the gene onto chromosomes and into DNA, then shows how genes are copied, changed, expressed and controlled, how modern tools read and edit genomes, and how genetics works across populations and complex traits.
6 units · 26 lessons
Unit 1 · Inheritance
- Unit 1: Inheritance Mendel's Peas: Segregation and Independent Assortment Mendel counted 7,324 seeds from his round-by-wrinkled hybrids: 5,474 round and 1,850 wrinkled. Why near 3 to 1?
- Unit 1: Inheritance Chromosomes and Meiosis: The Physical Basis of Mendel's Laws A fruit fly cell has eight chromosomes and its sperm have four. Which four is settled at one step of one division.
- Unit 1: Inheritance Probability, Crosses and the Chi-Square Test Mendel expected 312.75 round yellow seeds and counted 315. How far off can a count be before the ratio is wrong?
- Unit 1: Inheritance Extending Mendel: Dominance, Multiple Alleles and Gene Interaction Mate two yellow mice as often as you like: you will never get a yellow mouse that breeds true. Why?
- Unit 1: Inheritance Reading Pedigrees: Human Inheritance Your brother has cystic fibrosis and you do not. Is your chance of being a carrier 1/2 or 2/3?
- Unit 1: Inheritance Sex Linkage, Dosage Compensation and Non-Mendelian Inheritance Cross a white-eyed fly one way and the sons and daughters match. Cross it the other way and they do not. Why?
- Unit 1: Inheritance Chromosome Number and Structure: Aneuploidy and Rearrangements In 1959 a laboratory in Paris counted 47 chromosomes, not 46, in cells from children with Down syndrome.
Unit 2 · Mapping and gene function
- Unit 2: Mapping and gene function Linkage and Recombination Mapping Of 1,000 test-cross flies, Mendel predicts 500 that look like a grandparent. Why do 830?
- Unit 2: Mapping and gene function Three-Point Crosses: Gene Order and Double Crossovers Two crossovers between the same pair of genes cancel out. How do you count what you cannot see?
- Unit 2: Mapping and gene function Complementation and Gene Function: From Beadle and Tatum to Benzer Two pure-breeding white-eyed flies can have red-eyed offspring. What does that tell you about their genes?
- Unit 2: Mapping and gene function Bacterial and Phage Genetics: Conjugation, Transduction and Transformation Two E. coli strains that each cannot make several nutrients are mixed. A few cells can now make them all. Where did the genes come from?
Unit 3 · DNA: copying, changing, repairing
- Unit 3: DNA: copying, changing, repairing DNA Is the Genetic Material Dead bacteria changed living ones into their own type. What was passed across?
- Unit 3: DNA: copying, changing, repairing DNA Replication: Semiconservative Copying and Its Machinery One generation after a switch from heavy to ordinary nitrogen, all of E. coli's DNA sat halfway between heavy and light. Why halfway?
- Unit 3: DNA: copying, changing, repairing Mutation: Where Variation Comes From Ten identical bacterial cultures meet the same virus. Why does one give 52 survivors while five give none?
- Unit 3: DNA: copying, changing, repairing DNA Repair and Recombination Humans have no photolyase, the enzyme that lets bacteria and plants undo UV damage with light. So how do your skin cells fix sunburned DNA?
Unit 4 · From gene to protein, and its control
- Unit 4: From gene to protein, and its control Transcription: From DNA to RNA Which strand of a gene does RNA polymerase read, and which way does it go?
- Unit 4: From gene to protein, and its control RNA Processing: Caps, Tails and Splicing Why is a message copied from more than 5,000 nucleotides of DNA only 737 nucleotides long?
- Unit 4: From gene to protein, and its control The Genetic Code and Translation Sixty-four codons, twenty amino acids, three stops: how was the dictionary read, and who reads it in the cell?
- Unit 4: From gene to protein, and its control The lac Operon: How Bacteria Regulate Genes Give E. coli glucose and lactose together and it eats the glucose first, pauses, then starts on the lactose. How does it choose?
- Unit 4: From gene to protein, and its control Eukaryotic Gene Regulation and Epigenetics A liver cell and a kidney cell share one genome. How does each read a different part of it, and remember which part after it divides?
- Unit 4: From gene to protein, and its control Cancer as a Genetic Disease Every cell of a child who inherits one broken RB1 allele carries it. Why do only a few of those cells become tumors?
Unit 5 · Tools and genomes
- Unit 5: Tools and genomes Recombinant DNA, Cloning and PCR Thirty rounds of copying can turn ten molecules of DNA into about ten billion. Why does a real reaction stop short?
- Unit 5: Tools and genomes Sequencing and Genomes Two drafts of the human genome appeared in 2001. Why did a gapless one take until 2022?
- Unit 5: Tools and genomes Forward and Reverse Genetics: Screens, RNAi and CRISPR You cut both copies of a gene in every cell of a dish. Why is half the dish still making the protein?
Unit 6 · Populations and complex traits
- Unit 6: Populations and complex traits Population Genetics: Hardy-Weinberg and Evolutionary Forces If a trait is dominant, why does it not take over a population?
- Unit 6: Populations and complex traits Complex Traits, Heritability and GWAS If height is 80 percent heritable, is 80 percent of your height genetic? No, and the reason is the whole lesson.