Lecture 32_Variations to Mendel's Principles

Mendel's Principles

Fundamental laws of inheritance proposed by Gregor Mendel, including the Law of Segregation and the Law of Independent Assortment.

Locus

The specific physical location of a gene on a chromosome, akin to a genetic street address.

Law of Segregation

The principle stating that alleles segregate independently into gametes during meiosis.

Law of Independent Assortment

The principle stating that genes for different traits segregate independently of one another during the formation of gametes.

Incomplete Dominance

A form of inheritance where the phenotype of the heterozygote is intermediate between the phenotypes of the two homozygotes.

Codominance

A form of inheritance where both alleles are fully expressed in the phenotype of the heterozygote.

Multiple Alleles

A situation where a gene has more than two alleles, leading to a variety of phenotypes.

Pleiotropy

The phenomenon where one gene influences multiple, seemingly unrelated phenotypes.

Epistasis

A genetic interaction where the effect of one gene is completely masked by another gene.

Polygenic Inheritance

A type of inheritance where multiple independent genes collectively influence a trait, resulting in a continuous distribution of phenotypes.

Phenotypic Ratio of Incomplete Dominance

Changes from 3:1 in complete dominance to 1:2:1 in incomplete dominance.

ABO Blood Type

A human example of codominance determined by the alleles IA, IB, and i.

Degrees of Dominance

Refers to how completely one allele overshadows the other, including complete dominance, incomplete dominance, and codominance.

Skin Color Inheritance

An example of polygenic inheritance where multiple genes affect the phenotype of skin color.

Dominant Allele

An allele that expresses its phenotype even when heterozygous with a recessive allele.

Recessive Allele

An allele that only expresses its phenotype when homozygous.

Genotype

The genetic constitution of an individual.

Phenotype

The observable physical or biochemical characteristics of an individual.