Unveiling Dominance in Biology: Understanding the Role of Dominant Alleles in Determining Phenotype

Dominant

In biology, the term “dominant” refers to a trait or allele that is expressed or observed in an organism’s phenotype (physical characteristics) when at least one copy of it is present

In biology, the term “dominant” refers to a trait or allele that is expressed or observed in an organism’s phenotype (physical characteristics) when at least one copy of it is present. It is denoted by a capital letter (such as “A”) in genetic notations.

When an organism has two different alleles for a particular gene, one allele is usually dominant over the other. This means that the dominant allele masks the expression of the recessive allele. Consequently, the dominant allele is the one that determines the phenotype of the organism.

For example, let’s consider the trait of eye color in humans. The gene for eye color has multiple alleles, but for simplicity, let’s say there are two alleles: brown (B) and blue (b). The brown allele is dominant over the blue allele. Therefore, if an individual has at least one copy of the brown allele (BB or Bb), their eyes will appear brown. Only individuals with two copies of the blue allele (bb) will have blue eyes.

However, it is important to note that dominance is not an absolute quality. There are cases where alleles do not adhere strictly to the dominant or recessive pattern. In incomplete dominance, for instance, both alleles contribute to the phenotype, creating an intermediate or blended expression. An example of this is seen in snapdragons, where red and white alleles produce pink flowers when they occur together.

In summary, dominance refers to the Mendelian inheritance pattern where one allele (dominant) masks the expression of another (recessive) in an organism’s phenotype.

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