Here's a breakdown:
* Gene: A segment of DNA that codes for a specific protein.
* Allele: A variation of a gene. You inherit one allele from each parent.
* Heterozygous: Having two different alleles for a particular gene.
* Homozygous: Having two identical alleles for a particular gene.
For example, let's say there are two alleles for eye color: brown (B) and blue (b). A person with one brown allele (B) and one blue allele (b) is heterozygous for eye color. The trait they express will depend on whether the brown allele is dominant or recessive.
* Dominant allele: An allele that masks the expression of the other allele. In this case, if brown is dominant, the person will have brown eyes.
* Recessive allele: An allele that is only expressed when two copies of it are present. If blue is recessive, the person will only have blue eyes if they have two blue alleles (bb).
So, in the case of the heterozygous individual with one brown and one blue allele, they would express the dominant trait (brown eyes) if brown is dominant, or the recessive trait (blue eyes) if blue is dominant.
