Biology · Genetics
Genetics
Cross parents, fill the Punnett square and meet the offspring in 3D.
Also on your phone · Genetics Lab
The course
8 worlds · 52 lessons
World 1 · Mendel Basics
FREEAlleles, dominance & the monohybrid cross- 01What is a trait?Genes, alleles & the Glimmerbeast · 5 min
- 02Dominant & recessiveWhich allele you see · 5 min
- 03Genotype vs phenotypeThe code and the creature · 6 min
- 04The monohybrid crossBreeding one trait · 7 min
- 05The Punnett squareA grid for predicting offspring · 7 min
- 06Reading ratiosGenotype vs phenotype ratios · 6 min
- 07Homozygous crossesTrue-breeding lines · 6 min
- 08World 1 lab challengeBreed a cream Glimmerbeast · 8 min
World 2 · Dihybrid & Probability
PROTwo traits, independent assortment & the odds- 01Two traits at onceThe dihybrid cross · 7 minPRO
- 02Independent assortmentMendel’s second law · 7 minPRO
- 03The 9:3:3:1 ratioReading the dihybrid grid · 8 minPRO
- 04The product ruleMultiply independent odds · 6 minPRO
- 05The sum ruleAdd mutually exclusive odds · 6 minPRO
- 06The test crossRevealing a hidden genotype · 7 minPRO
- 07Branch diagramsProbability without the grid · 7 minPRO
- 08World 2 lab challengeHit a two-trait target · 9 minPRO
World 3 · Beyond Mendel
PROBlends, co-expression, multiple alleles & sex-linkage- 01Incomplete dominanceWhen the heterozygote blends · 7 minPRO
- 02CodominanceBoth alleles show at once · 7 minPRO
- 03Multiple allelesMore than two variants · 7 minPRO
- 04Dominance hierarchiesRanking the alleles · 7 minPRO
- 05Sex-linked traitsGenes on the S-chromosome · 8 minPRO
- 06Polygenic traitsMany genes, one feature · 7 minPRO
- 07EpistasisOne gene masking another · 8 minPRO
- 08PleiotropyOne gene, many effects · 6 minPRO
- 09Environment & expressionGenes are not the whole story · 6 minPRO
- 10World 3 lab challengeBlend and co-express · 9 minPRO
World 4 · Population Genetics
PROAllele frequencies, Hardy–Weinberg, DNA & mutation- 01Allele frequenciesCounting alleles in a population · 7 minPRO
- 02The Hardy–Weinberg equationPredicting genotype frequencies · 8 minPRO
- 03Equilibrium conditionsWhen frequencies stay put · 7 minPRO
- 04Pedigree analysisReading a family tree · 8 minPRO
- 05DNA & base pairingThe molecule behind the allele · 7 minPRO
- 06MutationsWhen a base is misplaced · 7 minPRO
- 07Selection & driftHow frequencies change · 8 minPRO
- 08World 4 lab challengeEngineer a helix · 10 minPRO
World 5 · Linked Genes
PRORecombination, map distance, and the end of 9:3:3:1- 01Genes that travel togetherWhy 9:3:3:1 is only sometimes true · 7 minPRO
- 02Map distanceCentimorgans and recombination frequency · 7 minPRO
- 03Coupling and repulsionWhich alleles started on which chromosome · 8 minPRO
- 04A linked cross, class by classWhat the litter actually looks like · 9 minPRO
- 05Measuring it: the testcrossTurning a litter into a distance · 9 minPRO
- 06How many offspring is enough?Sampling error, and the World 5 challenge · 10 minPRO
World 6 · Chromosomes in motion
PROMitosis, meiosis and reshuffling alleles
World 7 · From DNA to a peptide
PRODirection, copying, transcription and translation
World 8 · Natural selection
PROColour, predators and many generationsRead first
All guides →Guides for Genetics
Exam prepGeneticsAP and IB Biology: Cells and Genetics Study GuidePlan your revision of cell structure and Mendelian genetics for AP and IB Biology, with free interactive lessons, common pitfalls and a simple weekly study plan.
ExplainerHuman BodyHow the Human Body Is Organized: Cells, Tissues, BonesSee how cells build tissues, tissues build organs, and how the skeleton works as a living frame of bones, joints, cartilage and ligaments. With a live 3D lab.
ExplainerGeneticsPunnett Squares Explained: Mendel’s Rules of InheritanceLearn alleles, dominant and recessive traits, genotype versus phenotype and how to fill a Punnett square, then breed virtual creatures in a live 3D lab.