Complex Inheritance Patterns Flashcards

Vocabulary-style flashcards covering incomplete dominance, codominance, blood types, multiple alleles, polygenic inheritance, epistasis, and sex-linked traits.

Complex Inheritance

A pattern where alleles are neither strictly dominant nor recessive, and traits may be controlled by multiple alleles or multiple genes.

Incomplete Dominance

A pattern of inheritance where the heterozygous phenotype is a blend somewhere between the two homozygous phenotypes, such as pink flowers produced from red and white parents.

Wavy hair ($HH'$)

The heterozygous phenotype in humans resulting from incomplete dominance between curly hair ($HH$) and straight hair ($H'H'$).

Codominance

A pattern where both traits are fully and separately expressed, such as red and white speckled flowers or $AB$ blood type.

Appaloosa Horse

The heterozygous ($BW$) phenotype of a horse that is white with brown spots, resulting from codominance between brown ($BB$) and white ($WW$) traits.

Multiple Alleles

Having more than two alleles for one gene, such as the alleles $A$, $B$, and $i$ for human blood types or fur color in rabbits.

Agglutinogens

Antigens located on red blood cells (RBCs) that determine an individual's blood type.

Antibodies

Proteins in the plasma that bind and attack foreign antigens; for example, Type A blood contains Anti-B antibodies.

Type O Blood

A blood type characterized by having no agglutinogens on the red blood cells, Anti-A and Anti-B antibodies in the plasma, and the genotype $ii$.

Polygenic Inheritance

A trait produced by two or more genes that usually results in a range of phenotypes, such as skin color, eye color, height, and personality.

Epistasis

A condition where one gene overshadows or modifies the phenotypic expression of all other genes, seen in Labrador retriever fur colors and albinism.

Linked Genes

Genes physically located on the same chromosome that tend to be inherited together, like blonde hair and blue eyes.

Crossing Over

The biological process during which linked genes can be separated or broken apart.

Autosomes

The first $22$ pairs of chromosomes that are identical in both males and females.

Sex Chromosomes

The last pair of chromosomes ($XX$ for females and $XY$ for males) that determine the biological sex of the individual.

X-Linked Genes

Genes located on the $X$ chromosome; females inherit two copies and follow the principle of dominance, while males express the single copy they inherit regardless of whether it is dominant or recessive.

Carrier

An individual (usually female) who carries a recessive trait on one $X$ chromosome but does not express it because it is masked by a dominant allele on the other $X$ chromosome.