Understanding Gene Expression: The Role of Dominant and Recessive Alleles in Shaping Organism Traits

True or false?- Organisms with alternate forms of a gene will express the form that is recessive.

False

False. Organisms with alternate forms of a gene, known as alleles, do not always express the recessive form. The expression of a gene depends on whether the allele is dominant or recessive.

In genetics, dominant alleles are those that mask the presence of a recessive allele, meaning even if an individual carries both a dominant and a recessive allele for a particular gene, the dominant allele will dictate the phenotype or physical expression of the trait.

On the other hand, recessive alleles are only expressed when an individual carries two copies of the recessive allele, one inherited from each parent. If an individual carries one dominant allele and one recessive allele, they will display the phenotype associated with the dominant allele.

For example, let’s consider the gene for hair color. Let’s say having brown hair is dominant (B) and having red hair is recessive (b). If an individual has the genotype BB (two copies of the dominant allele), they will have brown hair. If they have the genotype Bb (one dominant and one recessive allele), they will still have brown hair because the dominant allele masks the presence of the recessive allele.

However, if an individual has the genotype bb (two copies of the recessive allele), they will express the recessive trait and have red hair.

In summary, the expression of alternate forms of a gene is determined by the dominance or recessiveness of the alleles involved, and it is not accurate to claim that organisms with alternate forms of a gene will always express the recessive form.

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