Genetics Lecture: Penetrance, Maternal Effects, and Epigenetics

Vocabulary flashcards focusing on non-Mendelian genetics topics from the lecture, including penetrance, maternal effect, snail shell coiling chirality, and epigenetic mechanisms.

Penetrance

The degree to which the genotype predicts the phenotype, or the degree to which a phenotypic outcome is predictable based on genetic information and environmental factors.

Maternal effect

A non-Mendelian inheritance pattern in which the genotype of the mother directly determines the phenotype of her offspring due to gene products accumulated in the egg from maternal nurse cells.

Dextral

The right-handed shell coiling pattern or chirality found in snails, which is the dominant phenotype associated with the $D$ allele.

Sinistral

The left-handed shell coiling pattern or chirality found in snails, which is the recessive phenotype associated with the $d$ allele.

Reciprocal cross

A pair of genetic crosses in which the sexes and phenotypes of the parent organisms are reversed relative to one another to test for sex-linked or maternal inheritance effects.

Nurse cells

Diploid maternal cells within the ovaries that nurture developing eggs and provide essential RNA and protein gene products to direct early embryogenesis.

Epigenetic inheritance

A pattern of inheritance where a modification to a nuclear gene or chromosome alters gene expression without changing the underlying DNA sequence.

Dosage compensation

An epigenetic mechanism that equalizes the expression of X-linked genes between males and females, such as by inactivating one X chromosome in female mammalian cells.