What is the difference between a gene and an allele?

What is the difference between a gene and an allele?

• A. A gene is a unit of heredity; an allele is a variant form of a gene.
• B. An allele is a unit of heredity; a gene is a variant form of a trait.
• C. Genes determine traits; alleles determine environment.
• D. Alleles are found only in plants.

Answer: (A)

Genes are the units of heredity—specific DNA sequences that code for a trait. An allele is a variant form of that gene, a different version of the same genetic instruction. Different alleles can lead to different expressions of the trait, such as one allele for brown eyes and another for blue eyes. In most organisms, you have two alleles for each gene (one from each parent), and which alleles you carry helps determine how the trait appears, with some alleles often being dominant over others. The other statements mix up the roles—an allele isn’t the unit of heredity itself, and environment isn’t determined by alleles. Alleles aren’t limited to plants, either.

Genes are the units of heredity—specific DNA sequences that code for a trait. An allele is a variant form of that gene, a different version of the same genetic instruction. Different alleles can lead to different expressions of the trait, such as one allele for brown eyes and another for blue eyes. In most organisms, you have two alleles for each gene (one from each parent), and which alleles you carry helps determine how the trait appears, with some alleles often being dominant over others. The other statements mix up the roles—an allele isn’t the unit of heredity itself, and environment isn’t determined by alleles. Alleles aren’t limited to plants, either.