Genetics and Inheritance

Flashcards covering key vocabulary and concepts from a lecture on genetics, including alleles, genotypes, Hardy-Weinberg equilibrium, adoption and twin studies, and heritability.

A allele

Normal allele (wild type).

a allele

Mutant allele.

AA

Homozygous wild genotype.

aa

Homozygous mutant genotype.

Aa

Heterozygous genotype.

Hardy-Weinberg equilibrium

Describes the principle that allele and genotype frequencies in a population remain constant from generation to generation unless specific disturbing influences are introduced.

p

Allele 1 frequency in Hardy-Weinberg equilibrium.

q

Allele 2 frequency in Hardy-Weinberg equilibrium.

p2

Frequency of AA genotype in Hardy-Weinberg equilibrium.

2pq

Frequency of Aa genotype in Hardy-Weinberg equilibrium.

q2

Frequency of aa genotype in Hardy-Weinberg equilibrium.

Parent-offspring resemblance

Reflects genetic + environmental factors.

Adoptive parent-offspring resemblance

Reflects environmental factors.

Bio parent-offspring resemblance

Reflects genetic factors.

Environmental siblings

Pairs of genetically unrelated children adopted early in life into the same adoptive home

Genetic siblings

Full siblings adopted APART early in life and reared in different homes

Monozygotic (MZ; “identical”)

Result from the fertilization of a single egg by a single sperm; share 100% of their genetic material.

Dizygotic (DZ, “fraternal” or “non-identical”)

Result from the independent fertilization of two eggs by two sperm; share on average 50% of their genes, can be same-sex or opposite-sex.

Equal environment assumption (EEA)

If the twins are raised in the same family, the environmental effect for the MZ and DZ twins are close to identical.

Heritability

The proportion of phenotypic variance that can be accounted for by genetic effects.

r (the correlation coefficient)

Represents similarity of pairs.

Total Phenotypic Variance

Genetic Effects + Environmental Effects

A

Additive genetic effects

D

Dominance genetic effects

C

Common (shared) environmental effects make siblings similar, e.g. shared parenting

U

Unique (unshared) environmental effects make siblings different, e.g. car accident