OBJECTIVES: The student will be able to:

1. identify the genotypes
2. accurately complete a Punnett Square
3. calculate the percentages for each genotype represented on the Punnett Square

GUIDELINES FOR COMPLETING A PUNNETT SQUARE

1. Place the genotype for the male above the square
2. Place the genotype for the female along the left side of the square
3. Bring the male gene from the left into the upper left hand box of the square along with the upper gene from the female
4. Bring the male gene from the left into the lower left hand box of the square along with the lower gene of the female
5. Bring the male gene from the right into the upper right hand box of the square along with the upper gene from the female
6. Bring the male gene from the right into the lower right hand box of the square along with the lower gene from the female

CALCULATING THE GENOTYPES OF OFFSPRING

Each of the inner boxes of the square represent a 25% chance that the offspring will have that combination of genetic information from his/her parent gametes.

When each of the squares is identifed as homozygous normal, herterozygous, or homozygous affected determine the out come for that particular Punnett Square in percentages. The total of all the information obtained in the square should be exactly 100%.

ACTIVITY

Develop the six Punnett Square possibilities for which genetic information may be given to the offspring involving the presence of an affected allele.

Introduction	Vocabulary	Micro-activity	Genetics activity
Punnett sq.	Punnett Sq. Illus.	Example of Pedigree	Assessment