Mendelian Genetics and Inheritance Patterns

A collection of vocabulary flashcards based on lecture notes covering Mendelian inheritance, non-Mendelian patterns, and genetic principles.

Mendelian genetics

A branch of genetics based on the laws of inheritance proposed by Gregor Mendel, involving dominant and recessive traits.

Complete dominance

A form of inheritance where the dominant allele completely masks the recessive allele, such as when a red flower ($RR$) crossed with a white flower ($rr$) produces all red offspring ($Rr$) in a ratio of $4 \text{ (Red)} : 0 \text{ (white)}$.

Incomplete dominance

A pattern of inheritance where neither allele is completely dominant, resulting in an intermediate phenotype, such as a black dog and white dog producing grey offspring in a ratio of $1 \text{ (Black)} : 2 \text{ (Grey)} : 1 \text{ (White)}$.

Codominance

A condition in which both alleles for a gene are fully expressed, such as fur color in cats that can be both brown and black simultaneously.

Polygenic trait

A characteristic, such as human skin color, that is controlled by the interaction of multiple different genes rather than a single gene.

Sex-linked trait

A trait associated with a gene that is carried only by the male or female parent on a sex chromosome, such as male pattern baldness being an X-linked trait.

Multiple alleles

An inheritance pattern where three or more alleles exist for a single gene, such as the human blood type system involving types A, B, and O.

Zygote

The cell produced by the union of two gametes, which is the direct result of fertilization.

Pedigree chart

A diagram representing a family tree that shows the occurrence of phenotypes across generations, used to determine the genotypes of individuals.

Mendel’s law of segregation

The principle stating that during gamete formation, the two alleles for each gene separate so that each gamete receives only one; this determines how alleles are distributed in a dihybrid cross.

Mendel’s law of independent assortment

The law stating that the alleles of different genes for various traits are distributed into gametes independently of one another.

Mutation

A change in the DNA sequence that can lead to alterations in genotypes and phenotypes.