Understanding Dominance in Genetics: Exploring the Powerful Influence of Dominant Alleles

Describes a trait that covers over, or dominates, another form of that trait.

The concept we are referring to is known as dominance in genetics

The concept we are referring to is known as dominance in genetics. Dominance occurs when one form of a trait, called the dominant trait, is expressed over another form of the trait, called the recessive trait.

To understand dominance, let us consider a classic example involving eye color in humans. The gene responsible for eye color has two versions or alleles: brown (dominant) and blue (recessive). If an individual inherits one copy of the brown allele (B) and one copy of the blue allele (b), the brown allele will be dominant and determine the individual’s eye color.

In this scenario, the dominant allele (B) covers over or masks the expression of the recessive allele (b). Therefore, the individual will have brown eyes. This is because the genetic instructions encoded by the brown allele are sufficient to produce the brown pigment, which results in brown eye color.

On the other hand, if an individual inherits two copies of the recessive allele (bb), both alleles are the same and no dominant allele is present to mask its expression. Consequently, the recessive allele will be expressed, leading to blue eye color.

In simple terms, dominance occurs when one allele is more influential than the other in determining the observable trait. The dominant allele “covers over” the recessive allele, so its characteristics are expressed while the recessive allele’s characteristics are not visibly seen.

It is important to note that dominance is not always absolute, and there are cases of incomplete dominance where a blend of both traits is observed. In these situations, neither allele fully dominates the other, resulting in an intermediate or blended phenotype. Additionally, there are instances of co-dominance where both alleles are expressed simultaneously without one allele dominating the other.

Dominance serves as a fundamental principle in genetics, helping to explain the inheritance patterns of traits and the variations seen in different generations.

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