Dominant and Recessive Genes
Your genes will determine your eye color, depending on which gene is recessive and which is dominant.
Goal:
Goal:
Imagine that in one family both children have brown eyes. One child has a pure trait for brown eyes because both parents gave him a brown-eyed gene. When an offspring has two of the same alleles, he is homozygous. The other child is a hybrid for brown eyes because one parent gave her a blue-eyed gene, which is recessive, and the other parent gave her a brown-eyed dominant gene, which has shown up. This is called heterozygous, or the child has two different alleles for the trait.
A Punnett square can be used to predict what traits an offspring will display. To complete a Punnett square you need to know the allele, or form of the trait the parent has. For the child mentioned above, both parents have brown eyes, but one is homozygous, which means he is made up of BB, and one is heterozygous, which means he is made up of Bb.
Fill in the following Punnett square by clicking on the parent genes. Click on the B genes to check your answer.
| B | B | |
| B | BB | BB |
| b | Bb | Bb |
All of these offspring will have brown eyes because there is a dominant B (brown eye) trait in each square.