Understanding Dominance in Genetics: The Influence of Alleles on Phenotype

Dominant

In the context of genetics, dominance refers to the expression of certain traits over others in an individual’s phenotype

In the context of genetics, dominance refers to the expression of certain traits over others in an individual’s phenotype. It is the concept that some alleles (alternative forms of a gene) mask or overpower the expression of other alleles, resulting in the dominant allele being observed in the phenotype. The allele that is overpowered or masked is referred to as recessive.

Dominant traits are expressed when an individual carries at least one copy of the dominant allele. It means that the presence of a dominant allele will always result in the appearance of the associated trait, regardless of whether the second allele is dominant or recessive. On the other hand, recessive traits are only expressed if an individual carries two copies of the recessive allele.

To better understand the concept of dominance, let’s consider an example with eye color. In this example, let’s assume that the allele for brown eye color is dominant (B), while the allele for blue eye color is recessive (b). Individuals can have three possible genotypes: BB (homozygous dominant), Bb (heterozygous), or bb (homozygous recessive).

If an individual has the genotype BB or Bb, they will express the brown eye color because the dominant allele (B) masks the expression of the recessive allele (b). Only individuals with the genotype bb will have blue eyes because they do not possess the dominant allele to override the expression of the recessive allele.

It is important to note that dominance does not imply that a particular phenotype is more common in a population. It simply means that a dominant allele will mask the expression of a recessive allele when present. In some cases, the dominance relationship between alleles can be incomplete, resulting in an intermediate phenotype in heterozygotes. This is known as incomplete dominance.

Overall, the concept of dominance is crucial in understanding how genetic traits are expressed and inherited. It helps explain the variation and patterns seen in our phenotypes, and it is fundamental to many branches of biology, such as genetics and evolutionary biology.

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