## Using a Punnett Square

### Biology - High School

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##### 1. What Is a Punnett Square?
A Punnett square is a chart that shows the allele combinations from a genetic cross. It helps predict the probability of a parental trait showing up in the offspring.
##### 2. Information for a Punnett Square
To make a Punnett square, you need to know the genetic information from each parent. Each parent has two alleles, symbolized with letters.
##### 3. Drawing a Punnett Square
When you make a Punnett square, the first step is to draw a square and divide it into four boxes.
##### 4. Parental Alleles on a Punnett Square
Then, write one parent's alleles above the two boxes on the top and the other parent's alleles along the left side.
##### 5. Filling in a Punnett Square
Copy the parent's alleles into the boxes, moving across the rows. Then copy the other parent's alleles into the boxes moving down the columns.
##### 6. Completed Punnett Square
Each box now has two alleles, one from each parent. These boxes represent the genetic combinations that can occur in the offspring.
##### 7. Allele Combinations and the Punnett Square
In this cross, there are three possible allele combinations for the offspring.
##### 8. Probability and the Punnett Square
The probability of these combinations showing up in the offspring can also be determined.