Meiosis

Blending Inheritance

Early theory that hereditary determinants blend irreversibly in the zygote, producing intermediate phenotypes[cite: 2].

Particulate Inheritance

Mendel's theory that hereditary determinants (genes) remain distinct and intact at fertilization[cite: 2].

Allele

Different forms of a specific gene[cite: 2].

Homozygous

An organism that has two identical alleles for a gene, such as RR or rr[cite: 2].

Heterozygous

An organism that has two different alleles for a gene, such as Rr[cite: 2].

Phenotype

The physical appearance or observable traits of an organism[cite: 2].

Genotype

The genetic constitution or allele combination of an organism[cite: 2].

Law of Segregation

Mendel's first law stating that the two copies of a gene separate during gamete formation so each gamete receives only one copy[cite: 2].

Test Cross

Crossing an individual with a dominant phenotype but unknown genotype with a homozygous recessive individual to determine if they are heterozygous[cite: 2].

Law of Independent Assortment

Mendel's second law stating that copies of different genes assort independently of one another during gamete formation[cite: 2].

Incomplete Dominance

A pattern where heterozygotes show an intermediate phenotype, and the original phenotypes reappear in the F2 generation[cite: 2].

Codominance

A pattern where two different alleles both produce phenotypes that are fully present in the heterozygote, such as ABO blood groups[cite: 2].

Epistasis

A gene interaction where the phenotypic expression of one gene is influenced or masked by a different gene, such as coat color in Labrador retrievers[cite: 2].

Expressivity

The degree to which a genotype is expressed in an individual's phenotype, which can be influenced by temperature and environment[cite: 2].

Quantitative Variation

Continuous phenotypic variation usually caused by the additive effects of multiple genes and the environment[cite: 2].

Recombinant Frequency

The proportion of offspring that have non-parental allele combinations due to crossing over, used to map genetic distances[cite: 2].

Genetic Map Unit (Centimorgan)

A measurement of distance between genes on a chromosome, where one map unit equals a 1% recombinant frequency[cite: 2].

Sex-Linked Inheritance

Traits carried on a sex chromosome (like the X chromosome) that appear much more often in males because they lack a second X chromosome to mask the mutation[cite: 2].