The phrases dominant and recessive refer to the patterns of inheritance for specific features. That is, they quantify the likelihood of a particular phenotype being transmitted from parent to offspring.
Each gene is duplicated in sexually reproducing species, including humans and other animals. The two copies, referred to as alleles, can differ significantly from one another. The variances may result in variations in the protein produced, or they may alter protein expression: the timing, location, and amount of protein generated. Because proteins influence characteristics, differences in their activity or expression might result in distinct phenotypes.
A dominant allele results in a dominant phenotype in people who have a single copy of the allele, which can be inherited from only one parent. To have a recessive phenotype, a person must have two copies of the recessive allele, one from each parent. A dominant phenotype is one in which an individual has one dominant and one recessive allele for a gene. They are sometimes referred to as “carriers” of the recessive allele since the recessive allele is present but the recessive phenotype is absent.