A homozygous dominant individual has two copies of the dominant allele for a gene (for example, AA instead of Aa or aa).

Quick Scoop: What that really means

  • “Homozygous” = both alleles are the same at a gene (like AA or aa).
  • “Dominant” = this allele is the one that shows up in the trait, even if just one copy is present.
  • Put together, homozygous dominant = two dominant alleles, usually written as something like AA or BB.

So if A is the dominant allele for brown eyes, then:

  • AA = homozygous dominant → brown eyes.
  • Aa = heterozygous → still brown eyes (because A is dominant).
  • aa = homozygous recessive → the recessive trait shows (like blue eyes).

A classic example: pea plants with PP for purple flowers are homozygous dominant for purple-flower color, and they will always pass on a P allele to their offspring.