Part of Lesson Plan: Punnett Square Discovery
Activity Overview / Details
Let's practice with sheep. Unfortunately sheep have a condition
called "spider lamb" due to inbreeding in the Suffolk breed. Let's
see if we can determine how many lambs will be spiders based on the
genetics of the parents.
1. Normal body type is dominant over the spider condition (thank goodness!)
2. N = normal n = spider
3. If a ram is "clean" or in other words has a clean pedigree, and is bred to carrier (heterzygous) ewes, how many of the lambs will be spider lambs?
4. If a ram is heterozygous for the spider gene and is bred to heterozygous ewes, how many lambs will be spider lambs?
5. If you have a flock of 100 ewes that are all heterozygous bred to a heterozygous ram, and every lamb that is born that is free of the spider gene is worth $500, a lamb that is normal appearing but a carrier for the gene is worth $100, and a spider lamb, well, is worth $0 because it is going to die, what will be your income from your flock?
Show all your work for full credit!
6. Now, it is time to complete the lab about probability and monohybrid crosses.
Materials / Resource
- punnett square lab.doc [ Download ] This lab should be completed once the students understand how the Punnett square helps to predict the offspring.