Genetic terms 7-2.5

Genes

A segment of DNA found on a chromosome that determines the inheritance of a particular trait. Genes are responsible for the inherited characteristics that distinguish one individual from another. Genes for a specific trait generally come in pairs. One gene from the pair is called an allele. Genes may be expressed in two different forms. Genotype—the set of genes carried by the organism. Phenotype—the physical expression of the genes. Inherited traits Characteristics that are passed from parent to offspring. Examples of inherited traits may be eye color, eye shape, hair type, or face shape. Some inherited traits are dominant and some are recessive. Dominant trait—A trait that will always be expressed in the phenotype. Alleles for dominant traits are represented by capital letters. Recessive trait—A trait that will only be expressed in the phenotype if two recessive alleles are present. In the presence of a dominant trait, the recessive trait will not be expressed. Alleles for recessive traits are represented by lowercase letters.

Chromosomes

A structure found in the nucleus of a cell that contains the genetic information (DNA)

Dominant traits

A trait that will always be expressed in the phenotype

Recessive traits

A trait that will only be expressed in the phenotype if two recessive alleles are present

Inherited traits

Characteristics that are passed from parent to offspring

Heredity

Is the passing of traits from one generation to the other; or inheritance

Allele

One of the two pairs of genes found in chromosomes

Phenotypes

The physical expression of the genes

Genotypes

The set of genes carried by the organism