Recessive traits

Definition

Recessive traits are traits that are expressed only when two copies of the recessive allele are present. They remain masked by dominant traits in heterozygous pairings.

5 Must Know Facts For Your Next Test

1. 1. Recessive traits can skip generations and reappear if both parents contribute a recessive allele.
2. 2. Gregor Mendel discovered the concept of recessive traits through his experiments with pea plants.
3. 3. An organism must have two recessive alleles (homozygous recessive) for the trait to be expressed.
4. 4. The presence of a dominant allele will mask the expression of a recessive trait in a heterozygous pairing.
5. 5. Examples of human recessive traits include blue eyes, attached earlobes, and cystic fibrosis.

Review Questions

• 1. What is required for a recessive trait to be expressed in an organism?
• 2. How did Gregor Mendel's experiments contribute to our understanding of recessive traits?
• 3. Can a person carry a recessive trait without expressing it? Explain why or why not.

Related terms

Dominant Trait: A trait that is expressed when at least one dominant allele is present in the genotype.

Heterozygous: Having two different alleles for a specific gene, one dominant and one recessive.

Homozygous: Having two identical alleles for a specific gene, either both dominant or both recessive.