Here's a breakdown:
* Alleles: Alternative forms of a gene that determine a specific trait.
* Dominant allele: An allele that masks the expression of another allele (the recessive allele) when they are present together in a heterozygous individual.
* Recessive allele: An allele whose expression is masked by a dominant allele in a heterozygous individual.
Example:
Let's consider eye color. If "B" represents the brown eye allele and "b" represents the blue eye allele, and "B" is dominant:
* BB: Homozygous dominant - Brown eyes
* Bb: Heterozygous - Brown eyes (the dominant "B" masks the "b")
* bb: Homozygous recessive - Blue eyes
Therefore, uppercase letters represent the alleles that will be expressed, even if only one copy is present (heterozygous).
