Genetics and Inheritance

Flashcards covering key vocabulary and concepts from the genetics lecture notes.

A (Allele)

Normal allele (wild type).

a (Allele)

Mutant allele.

AA

Homozygous wild genotype.

aa

Homozygous mutant genotype.

Aa

Heterozygous genotype.

Hardy-Weinberg Equilibrium

The principle stating that the frequencies of alleles and genotypes in a population remain constant from generation to generation unless specific disturbing influences are introduced

aa (PKU)

Individuals affected by PKU (phenylketonuria).

Aa (PKU)

PKU carriers.

Adoptive parent-offspring resemblance

Reflects environmental factors.

Biological parent-offspring resemblance

Reflects genetic factors.

Genetic siblings in adoption studies

Share only genes; resemblance reflects genetic factors.

Environmental siblings in adoption studies

Share only environment; resemblance reflects environmental factors.

Monozygotic (MZ; identical) twins

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

Dizygotic (DZ; fraternal or non-identical) twins

Result from the independent fertilization of two eggs by two sperm; share on average 50% of their genes.

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

Similarity of pairs; correlation coefficient.

P = G + E (Total Phenotypic Variance)

Genetic effects + Environmental effects

A

Additive genetic effects.

D

Dominance genetic effects.

C

Common (shared) environmental effects that make siblings similar.

U

Unique (unshared) environmental effects that make siblings different.

Interpreting Heritability

Genetic contribution to individual differences (variance), not to the phenotype of a single individual.