A gene that is not expressed in the heterozygous condition is known as what?

A gene that is not expressed in the heterozygous condition is classified as recessive. This means that for the recessive trait to be phenotypically expressed in an organism, an individual must possess two copies of the recessive allele, one inherited from each parent. In contrast, if an individual has one dominant allele present alongside a recessive allele, the dominant trait will mask the expression of the recessive allele, leading to the dominant phenotype being displayed.

The concept of dominance and recessiveness is fundamental in genetics. In a homozygous condition (where both alleles are the same, either both dominant or both recessive), the expression will reflect the nature of that allele pair. However, when a heterozygous condition exists (one dominant and one recessive allele), the presence of the dominant allele dictates the phenotype.

This distinction is critical in understanding inheritance patterns, particularly in Mendelian genetics, where the behavior of alleles can determine traits passed down through generations. The other terms, such as codon and allele, relate to different aspects of genetics; for instance, a codon is a sequence of three nucleotides that represents a specific amino acid in protein synthesis, while an allele refers to the different versions of a