|MadSci Network: Genetics|
Greetings - Check out the links on the following page: Re: Explain the Punett Square . You might find some more examples on Punnett squares there. As long as you have every combination of alleles on the top row and first column of your Punnett square, you should be doing it right. An easier way, if you're looking for the probability of a certain genotype, is to do each cross independantly as a simple statistical probability problem. For example, if you're crossing TtSsAa X TtSsAa and wondering about the chance of getting TtSSaa, you could look at each trait separately and multiply the probabilities to get the combined probability. I.e. Tt X Tt gives 1/2 Tt Ss X Ss gives 1/4 SS Aa X Aa gives 1/4 aa (do a Punnett square if you're unconvinced of these numbers) So, the chance of TtSSaa together is 1/2X 1/4 X 1/4 = 1/32! In the real world, geneticists often find the above method much much easier than doing Punnett squares, though I do admit, they are fun! Sanjida Rangwala, Admin MadSci Network
Try the links in the MadSci Library for more information on Genetics.