PATHOLOGY

Detailed explanation-1: -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-2: -Alleles that exhibit complete dominance will always be expressed in the the cell’s phenotype. However, sometimes dominance of an allele is incomplete. In that that case, if a cell has one dominant and one recessive allele (i.e. heterozygous), the cell can display intermediate phenotypes.

Detailed explanation-3: -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-4: -From this, people often jump to the conclusion that the dominant trait is also the most common one. This isn’t always the case and there is no reason it should be. Whether or not a trait is common has to do with how many copies of that gene version (or allele) are in the population.