Understanding Dominant and Recessive Alleles: How Genes Determine Traits in Genetics

One dominant allele, one recessive allele

In genetics, traits are typically determined by the presence of specific alleles – alternative forms of a gene

In genetics, traits are typically determined by the presence of specific alleles – alternative forms of a gene. Alleles can be either dominant or recessive, and they play a role in how traits are expressed in an organism.

A dominant allele is one that is able to express itself, or be “seen,” if it is present in the genotype. This means that even if there is only one copy of the dominant allele in an individual’s genetic makeup, it will manifest as the dominant trait. For example, if we consider the trait of eye color, brown eye color is usually the dominant allele. So, if a person carries one copy of the brown allele (B) and one copy of the blue allele (b), their eye color will be brown because the brown allele is dominant.

On the other hand, a recessive allele is only expressed if it is present in a homozygous state, meaning an individual has two copies of that recessive allele. If only one copy of the recessive allele is present along with one copy of the dominant allele, the dominant trait will be expressed. Using the same example, if a person carries one copy of the dominant brown allele (B) and one copy of the recessive blue allele (b), their eye color will still be brown because the dominant allele masks the presence of the recessive allele.

In summary, one dominant allele can determine the expression of a trait in an individual if it is present in the genotype, while one recessive allele will only be expressed if it is present in a homozygous state (both alleles being recessive). It’s important to note that this is a simplified explanation, and in reality, traits are often influenced by multiple genes and can have more complex inheritance patterns.

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