Question

how do you do an punnett square?

Answer 1

Each individual parent has two alleles of any given gene. These two alleles each came one apiece from that individual's parents. So Mom gave the individual one allele and Dad gave the individual a second allele.

Let's say for argument's sake that one parent has a genotype Tt where T is a dominant allele and t is a recessive allele; let's say that the other parent has genotype tt, where each the alleles is recessive.

To set up a Punnett square, you put one parent's alleles on the top of the grid, the other parent's alleles on the side. Like so: