Dominant Allele

Key Stage 4

Meaning

A Dominant allele is an allele which can be expressed in the phenotype when there is only one copy of that allele.

About Dominant Alleles

When a genotype includes one dominant allele and one recessive allele the physical appearance of the person will be based on the dominant allele.

In a Punnett Square or Genetic Cross Diagram dominant alleles are written with a capital letter while the recessive alleles are written with a lower case letter.