Inheritance
Chromosomes, genes and proteins
- Chromosomesmade of DNAcontain genes
- Gene and allelegene: DNA coding for proteinallele: alternative form
- Inheritance of sexXX female, XY malesperm decides sex1 : 1 ratio
- Bases decide amino acidsSupplementamino acid sequencegives protein shape
- Making a proteinSupplementgene stays in nucleusmRNA copy to cytoplasmribosome assembles amino acids
- Gene expressionSupplementsame genes in body cellsonly some expressed
- Haploid and diploidSupplementhaploid: one setdiploid: two setshuman: 23 pairs
Mitosis and meiosisSupplement
- MitosisSupplementidentical cellschromosomes copied firstnumber maintained
- Roles of mitosisSupplementgrowthrepairreplacementasexual reproduction
- Stem cellsSupplementunspecialiseddivide by mitosisdaughters specialise
- MeiosisSupplementmakes gametesreduction divisiondiploid to haploidgenetically different
Monohybrid inheritance
- Key termsGenotypePhenotypeHomozygousHeterozygous
- Dominant and recessiveDominant: expressed if presentRecessive: needs no dominant
- Pure-breedingIdentical homozygous parentsHeterozygous: not pure-breeding
- Genetic diagramsPunnett squares3 : 1 ratio1 : 1 ratio
- Pedigree diagramsSquares male, circles femaleUnaffected parents, affected child: recessive
- Test crossSupplementUnknown × homozygous recessiveAll dominant: homozygousSome recessive: heterozygous
- CodominanceSupplementBoth alleles expressedABO: IA, IB, Io
- Sex linkageSupplementGene on X chromosomeColour blindnessMore common in males