Single Gene Inheritance & Probability Terminology

Self-Fertilization

Fertilization using gametes from the same organism; increases homozygosity

Cross-Fertilization

Fertilization between two different individuals; increases genetic variation

Testcross

A cross with a homozygous recessive organism to determine an unknown genotype

Backcross

A cross between offspring and one of its parents to reinforce a trait

Monohybrid Cross

A genetic cross involving one trait

Dihybrid Cross

A genetic cross involving two traits

Genotypic Ratio

The ratio of different genotypes in offspring

Phenotypic Ratio

The ratio of observable traits in offspring

Law of Independent Assortment

Alleles for different traits separate independently during gamete formation

Wild Type

The most common phenotype found in nature

Mutant

A version of a gene with a DNA change that alters the phenotype

Genotype

The genetic makeup of an organism

Phenotype

The observable traits of an organism

Homozygous

Having two identical alleles for a gene

Heterozygous

Having two different alleles for a gene

True-Breeding

Organisms that always produce offspring with the same traits

Hybrid

An organism that is heterozygous for a trait

Dominant Allele

An allele that masks the expression of another allele

Recessive Allele

An allele expressed only when two copies are present

Carrier

An individual with one recessive allele who does not show the trait