Classical Genetics and Evolution

MCAT Prep: Biology Part 6

Law of segregation

homologous alleles (chromosomes) separate so that each gamete has one cope of each gene

• If both parents are Rr, the alleles separate to give a genotypic ratio of 1:2:1 and a phenotypic ratio of 3:1

Law of independent assortment

alleles of unlinked genes assort independently in meiosis

• For two traits: AaBb parents will produce AB, Ab, aB, and ab gametes

• The phenotypic ratio for this cross is 9:3:3:1

product

The probability of producing a genotype that requires multiple events to occur equals the __________ of the probability of each event

sum

The probability of producing a genotype that can be the result of multiple different events equals the ________ of each probability minus the probability of multiple events occurring

Prophase I

crossing over during meiosis I can unlink genes

unlinked

Genes are most likely ________ when far apart

Autosomal recessive

may skip generations

Autosomal dominant

appears in every generation

X-linked (sex-linked)

no male-to-male transmission, and more males are affected

Hardy-Weinberg equilibrium

the population is in this when frequencies are stable; no mutations, large population, random mating, no migration, and equal reproductive success

p + q = 1

Hardy-Weinberg equilibrium equation with frequency of dominant and recessive alleles only

p² + 2pq + q² = 1

Hardy-Weinberg equilibrium equation with frequency of dominant and recessive alleles, homozygotes, and heterozygotes

p

frequency of dominant allele

q

frequency of dominant homozygotes

p²

frequency of dominant homoxygotes

2pq

frequency of heteroygotes

q²

frequency of recessive homozygotes