Definition

Noun: 1. A form of a gene whose phenotypic effect is masked by a dominant allele: A recessive allele is a variant of a gene that will only be expressed in an organism's observable traits (its phenotype) if the individual has two copies of that allele (one from each parent). If paired with a different, dominant allele, the recessive allele's trait will not be visible.

Usage

The term is used in the field of genetics to describe the inheritance pattern of specific traits. * The gene for blue eye color is a recessive allele. * For a child to have cystic fibrosis, they must inherit a recessive allele from both parents. * The plant carried the recessive allele for white flowers, but it displayed purple flowers because of the dominant allele.

Advanced Usage

• Carrier: An individual who possesses one copy of a recessive allele for a genetic disorder but does not exhibit the disorder because they also have a dominant, healthy allele. They can pass the recessive allele to their offspring.
  • Both parents were carriers of the recessive allele, leading to a 25% chance their child would have the condition.

Variants and Related Words

• Recessive (adjective): Describing the quality of an allele that is masked by a dominant allele.
  • The trait is recessive and requires two copies of the gene to appear.
• Dominant allele (noun): The contrasting form; an allele that produces its phenotypic effect even when paired with a different, recessive allele.
• Allele (noun): One of two or more alternative forms of a gene found at the same place on a chromosome.

Synonyms

• Recessive gene

Related Concepts

• Homozygous recessive: A genetic condition where an individual has two identical copies of a recessive allele for a particular gene.
  • Only individuals who are homozygous recessive for the trait will express it.
• Mendelian inheritance: The pattern of inheritance for traits affected by single genes with dominant and recessive alleles, as described by Gregor Mendel.

Noun

1. an allele that produces its characteristic phenotype only when its paired allele is identical