Genetic Terms

Allele

One of two or more different versions of the same gene.

Chromosome

A coiled structure made of DNA and proteins containing sister chromatids, which form a cell's genetic material.

Codominance

Relationships between two alleles for the same gene in which both alleles are expressed equally in the phenotype of the heterozygote.

Cross Fertilization

The process in which the sperm from one organism fertilizes the egg of another organism, increasing genetic diversity.

Dihybrid Cross

A cross between F1 offspring of two individuals that differ in two traits.

Dominant

An allele that masks the presence of another allele for the same gene when both alleles are present.

Genetic Linkage

The tendency of genes that are located close to each other on the same chromosome to be inherited together during meiosis.

Gene

A portion of DNA strand that codes for a protein.

Genetics

The study or science of heredity.

Genotype

Alleles an individual inherits at a particular genetic locus.

Heterozygous

An organism that inherits two different alleles for a given gene.

Homozygous

An organism that inherits two alleles of the same type for a given gene.

Hybrids

Offspring resulting from a cross between two different types of parents.

Intermediate Inheritance (Incomplete Dominance)

A relationship between the alleles for a gene in which one allele is only partly dominant to the other.

Locus

The position of a gene on a chromosome.

Monohybrid Cross

A genetic mix between two individuals who have different alleles at one genetic locus of interest.

Phenotype

Characteristics of an organism that depend on how the organism's genotype is expressed.

Polygenic (characteristics)

Characteristics controlled by more than one gene, each of which may have two or more alleles.

Punnett Square

Chart for determining the expected percentages of different genotypes in the offspring of two parents.

Recessive

An allele that is masked by the presence of another allele for the same gene in a heterozygote.

Sex-Linked

A gene located on a sex chromosome.

Testcross

A genetic experiment used to determine the genotype of an individual showing a dominant trait.

Trait

A specific characteristic or feature of an organism, often inherited from their parent.