Non-Mendelian Inheritance and Population Dynamics- week 4

Flashcards testing core vocabulary and key terms related to Non-Mendelian genetics, complex inheritance patterns, and gene interaction mechanisms.

X Inactivation

A genetic process in females where one of the two X chromosomes is randomly inactivated in each cell so that only one X chromosome is expressed.

Sex Limited Traits

Traits encoded by autosomal or X-linked genes that are only expressed in one sex, even though they can be inherited from and passed along by either sex.

Intersex

Naturally occurring developmental variations where reproductive or sexual anatomy does not fit typical male or female classifications, estimated to affect approximately $1.7\%$ of the population.

Locus

The specific physical chromosomal address or position of a gene, such as $7q31.2$ for the CFTR gene.

Multiple Alleles

A genetic pattern where three or more alternative forms of a gene exist within a population rather than just two.

Pseudodominance

A condition in which a heterozygous individual exhibits a recessive phenotype, making a recessive allele incorrectly appear dominant.

Penetrance

The proportion or percentage of individuals carrying a specific genetic variant that actually display the corresponding phenotypic trait.

Incomplete Penetrance

A situation where a gene or trait is not expressed in $100\%$ of the individuals who carry the allele.

Variable Expressivity

A characteristic of inheritance where individuals with the exact same genotype express the phenotype to varying degrees or intensities.

Anticipation

A genetic phenomenon where symptoms of a inherited disorder manifest at an earlier age and with increasing severity in successive generations due to expanded repeat sequences.

Stuttering Alleles

Unstable sections of DNA containing repetitive sequences (expandable repeats) that tend to expand in copy number across generations.

Epistasis

A gene interaction in which the alleles of one gene mask, modify, or override the phenotypic expression of a separate gene.

Digenic Inheritance

An inheritance pattern where expression of a specific phenotype or genetic disease requires concurrent mutations or specific alleles at two distinct loci.

Pleiotropy

A genetic phenomenon in which a single gene has multiple distinct biological effects on different phenotypic traits.

Polygenic Trait

A phenotypic trait whose expression is influenced and determined by the additive effect of multiple independent genes.

Genetic Heterogeneity

A situation where different genetic mechanisms or variations across multiple genes can lead to similar phenotypic outcomes.

Mitochondrial Inheritance

A non-Mendelian pattern of extranuclear inheritance where organellar genes are transmitted exclusively through the maternal lineage.

Y-Linked Inheritance

A mode of inheritance involving genes located on the Y chromosome, which are passed exclusively from father to sons.