Dominant

Definition

A dominant allele is one that expresses its trait in the phenotype when present, even if only one copy is inherited. It masks the presence of a recessive allele.

5 Must Know Facts For Your Next Test

1. Dominant alleles are represented by uppercase letters (e.g., 'A').
2. In heterozygous individuals, the dominant allele determines the observable trait.
3. Gregor Mendel's experiments with pea plants demonstrated how dominant traits are inherited.
4. A single copy of a dominant allele is enough to express the dominant phenotype.
5. Dominant alleles can mask recessive alleles in an organism's genotype.

Review Questions

• What is the representation of a dominant allele?
• How does a dominant allele affect a heterozygous individual's phenotype?
• Why was Gregor Mendel's work important for understanding dominance?

Related terms

Recessive:

An allele that only expresses its trait when two copies are present.

Heterozygous: Having two different alleles for a particular gene.

Phenotype: The observable characteristics or traits of an organism resulting from the interaction of its genotype with the environment.