A dominant allele is one copy of the gene that will always be expressed whether homozygous or heterozygous for the gene. The phenotype of the organism will show the dominant trait whenever this allele is present.
(WW) - Homozygous dominant (W phenotype expressed)
(Ww) - Heterozygous (W phenotype expressed - due to the dominant allele masking the expression of the recessive allele).
(ww) - Homozygous recessive (w phenotype expressed)
- ↑ Hartl. D and Ruvolo. M, (2012) Genetics. Analysis of Genes and Genomes, 8th Edition, Burlington: Jones and Barlett Learning.