Recessive<span> and </span>dominant alleles<span>. You will recall that genes have </span>different<span> forms called </span>alleles<span>. An </span>allele<span> can be </span>recessive<span> or </span>dominant<span>. A </span>recessive allele<span> only shows if the individual has two copies of the </span>recessive allele<span>.</span>
Recessive and dominant alleles are the two different forms of a gene that are also known as gene variants.
A dominant allele (represented by capital letter allele such as T for tall pea plant) is the one that masks the expression of a recessive allele.
It shows its phenotype even when a single copy of it is present in the genotype (such as in case of Tt, which represents Tall plant).
On the contrary, a recessive allele (represented by small letter allele such as 't' for dwarf) is the one that only shows its phenotype when present in a homozygous recessive form (like tt for dwarf). This is because it is masked when present with a dominant allele.
