🧫Genetics

Mendel's pea plants, the crosses that follow from his two laws, and the probability and chi-square tools that test whether real data fits them.

Mendel's Pea Plants and the Law of Segregation · Genotype, Phenotype, and the Monohybrid Cross · The Test Cross · Independent Assortment and the Dihybrid Cross · +6 more

What happens once alleles stop behaving in the simple dominant-recessive way Mendel's peas suggested.

Incomplete Dominance · Codominance · Multiple Alleles and ABO Blood Type · Lethal Alleles · +4 more

How chromosomes set an organism's sex, how genes on those chromosomes inherit differently as a result, and how family trees expose both patterns.

Chromosomal Sex Determination Systems · X-Linked Inheritance and the Criss-Cross Pattern · X-Inactivation and Mosaic Phenotypes · Y-Linked Inheritance · +4 more

The proof that Mendel's factors are physical chromosomes, and the cell divisions whose choreography is that proof in motion.

The Chromosomal Theory of Inheritance · Mitosis and Chromosome Behavior · Meiosis I: Homolog Pairing and Segregation · Meiosis II and the Haploid Products · +4 more

How genes riding on the same chromosome betray their order and distance through the recombinant offspring crossing over leaves behind.

Linked Genes and the Departure from Independent Assortment · Crossing Over Between Homologous Chromosomes · Recombination Frequency and Map Distance · Two-Point Testcross Mapping · +6 more

What happens when whole chromosome segments or whole chromosomes go missing, duplicate, flip, move, or multiply, and how that plays out at meiosis.

Chromosomal Deletions · Chromosomal Duplications · Chromosomal Inversions and the Inversion Loop · Translocations and Their Meiotic Pairing Consequences · +3 more

The molecule's own architecture, how it copies itself with almost no errors, and what happens on the rare occasions it doesn't.

The DNA Double Helix · Semiconservative Replication and the Meselson-Stahl Experiment · The Replication Fork: Leading and Lagging Strands · Enzymes of DNA Replication · +5 more

How a gene's DNA sequence becomes a working protein, from copying it into RNA to reading it three bases at a time on a ribosome.

The Mechanism of Transcription · RNA Processing: Splicing, Capping, and the Poly-A Tail · Alternative Splicing and One Gene, Many Proteins · The Genetic Code and Codons · +3 more

How bacteria switch whole gene sets on and off in response to their environment, and the layered controls eukaryotic cells add on top.

The Lac Operon and Inducible Regulation · The Trp Operon and Repressible Regulation · Eukaryotic Transcription Factors, Promoters, and Enhancers · Chromatin Structure and Gene Accessibility · +3 more

The lab tools that cut, copy, read, and now directly edit DNA, and how each one turns a molecular trick into a working technology.

Restriction Enzymes and DNA Cloning · Gel Electrophoresis · The Polymerase Chain Reaction · DNA Sequencing: Sanger and Next-Generation Methods · +2 more

Reading and comparing whole genomes at once, and what that scale reveals that gene-by-gene genetics never could.

Whole-Genome Sequencing and Assembly · Bioinformatics and Sequence Alignment · Comparative Genomics and Synteny · Gene Density and Noncoding DNA · +2 more

How a single fertilized egg's genes lay out a whole body plan, segment by segment, and what happens when one gene in that plan misfires.

Maternal Effect Genes and Early Embryo Patterning · The Segmentation Gene Cascade · Homeotic Genes and the Hox Cluster · Homeotic Mutations: Antennapedia and Bithorax · +2 more

Traits controlled by many genes at once, how to split their variation into genetic and environmental parts, and how breeders exploit that split.

Continuous Traits and the Normal Distribution · Polygenic Inheritance and Additive Alleles · Broad-Sense and Narrow-Sense Heritability · Twin Studies and Estimating Heritability · +2 more

How allele frequencies behave across a whole population under mating, selection, drift, migration, and inbreeding, and what that reveals about evolution.

Allele and Genotype Frequencies in a Population · Hardy-Weinberg Equilibrium · Testing Whether a Population Is in Hardy-Weinberg Equilibrium · Natural Selection Changing Allele Frequencies · +6 more