AP BIOLOGY

Detailed explanation-1: -Dominant alleles show their effect even if the individual only has one copy of the allele (also known as being heterozygous?). For example, the allele for brown eyes is dominant, therefore you only need one copy of the ‘brown eye’ allele to have brown eyes (although, with two copies you will still have brown eyes).

Detailed explanation-2: -A dominant allele produces a dominant phenotype in individuals who have one copy of the allele, which can come from just one parent. For a recessive allele to produce a recessive phenotype, the individual must have two copies, one from each parent.

Detailed explanation-3: -Individuals inherit two versions of each gene, known as alleles, from each parent. In the case of a dominant trait, only one copy of the dominant allele is required to express the trait.

Detailed explanation-4: -A dominant phenotype refers to a trait which is expressed in one of two conditions: the inheritance of two dominant alleles (homozygous dominant) or the inheritance of one dominant and one recessive allele (heterozygous dominant).

Detailed explanation-5: -So the dominant allele is always expressed, but it can differ in penetrance and is therefore not always as clearly expressed in the cell’s phenotype as you expect from a dominant allele.