Understanding Dominant Alleles in Genetics: The Basics Explained

Dominant

An allele that is always expressed

In genetics, dominant refers to an allele that masks the expression of another allele in the case of a heterozygous genotype. In simpler terms, if an individual has one copy of a dominant allele and one copy of a recessive allele, the dominant allele will determine the observable trait. This is because the dominant allele is expressed, while the recessive allele remains hidden or masked by the dominant allele. The dominant allele is often represented by a capital letter, while the recessive allele is represented by a lowercase letter. For example, in a pea plant, the allele for tall plant height (T) is dominant over the allele for short plant height (t). If a plant has one allele for tall height and one allele for short height (Tt), it will be tall because the dominant allele for tall height will be expressed.

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