Genetics Vocabulary

Allele

An alternative form of a gene that can occupy the same position on homologous chromosomes.

Carrier

An individual who has one allele for a recessive trait and can pass it to offspring but does not express the trait.

Codominance

A genetic situation in which both alleles are expressed equally in the phenotype of the heterozygote.

Dihybrid cross

A cross that examines the inheritance of two different traits.

Dominant

An allele that expresses its phenotype even in the presence of a recessive allele.

Fertilization

The process by which sperm and egg combine to form a zygote.

Gene

A segment of DNA that codes for a specific protein or trait.

Generations (P / F1 / F2)

P is the parental generation, F1 is the first generation of offspring, and F2 is the second generation of offspring.

Genetics

The study of heredity and the variation of inherited characteristics.

Genotype

The genetic constitution of an individual, often represented by alleles.

Gregor Mendel

The father of modern genetics known for his experiments with pea plants.

Heredity

The passing of traits from parents to offspring.

Heterozygous

An organism that has two different alleles for a particular gene.

Homozygous

An organism that has two identical alleles for a particular gene.

Hybrid

Offspring resulting from the cross between two genetically different individuals.

Incomplete dominance

A genetic situation where neither allele is completely dominant, resulting in a blended phenotype.

Independent assortment

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

Law of Segregation

The principle that pairs of alleles separate during gamete formation.

Multiple alleles

More than two possible alleles exist for a particular gene.

Pedigree

A diagram that shows the occurrence and appearance of phenotypes of a particular gene or organism and its ancestors.

Phenotype

The physical expression or characteristics of a trait.

Pleiotropy

A situation in which a single gene affects multiple traits.

Polygenic traits

Traits controlled by multiple genes, often showing a continuum of variation.

Principle of Dominance

The principle that states some alleles are dominant and others are recessive.

Punnett square

A diagram used to predict the genotypes of a genetic cross.

Recessive

An allele that is masked in the presence of a dominant allele and only expresses its phenotype in homozygous condition.

Sex-linked genes

Genes located on sex chromosomes, often associated with traits that are inherited differently in males and females.

Trait

A specific characteristic of an organism that can be observed or measured.

True-breeding

Organisms that, when mated, always produce offspring with the same phenotype.