How do dominant alleles and recessive alleles differ?

A dominant allele produces a dominant trait in individuals who have one copy of the allele, that can come from one parent. To produces a recessive trait, the child must have two copies of the recessive allele, one from each parent.

Explanation:

The terms dominant and recessive describe the patterns of certain traits. They describe how likely it is for certain traits to pass from parent offspring in humans and animals. The two copies of each gene (alleles), can be slightly different from each other. The differences can cause variations in the protein that's produced, Proteins affect traits, so variations in protein activity or expression can create different phenotypes.

A dominant allele produces a dominant phenotype (trait) in individuals who have one copy of the allele, which can come from one parent. For a recessive allele to produce a recessive phenotype, the individual must have two copies, one from each parent. A person with one dominant and one recessive allele for a gene will have a dominant phenotype. They are generally considered carriers of the recessive allele - the recessive allele is there, but the recessive phenotype is not.