HOW TO DO A PUNNETT SQUARE
IN 5 EASY STEPS
WHAT IS A PUNNETT SQUARE?

A punnett square is a chart that is used to
determine the possible combinations of genes
among offspring.
LET’S USE THE TRAIT OF DIMPLES AS AN EXAMPLE:
dominant= dimples (D)
 recessive= no dimples (d)

Mom= pure dominant = DD
 Dad= hybrid = Dd

STEP 1:

Write the genotypes of the parents
DD x Dd
STEP 2:

Make a punnett square
STEP 3:

Place one parent’s genes on the top of the
punnett square and the other parent’s genes
on the left side of the punnett square.
D
D
D
d
STEP 4:

Complete the punnett square by writing the
gene combinations in the appropriate boxes.
D
D
D
DD
DD
d
Dd
Dd
STEP 5:

Write the possible genotypes and phenotypes
of the offspring.
genotypes:
D
D
D
DD
DD
d
Dd
Dd
50% DD: 50% Dd: 0% dd
phenotypes:
100% dimples: 0% no dimples