Punnet Suaqres Im struggling can somebody please help?

Genetics as it applies to evolution, molecular biology, and medical aspects.

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Punnet Suaqres Im struggling can somebody please help?

Post by koqie » Sun Mar 12, 2006 8:15 pm

http://www.biologycorner.com/worksheets ... s_bio2.htm

Can somebody please go out of their way and help me on the worksheet on this site. This is an assignment I took home and Im really stumped. Im so aggrivated because im an excellent biology student but once we hit genetics my understanding just took a flop. It would be great if someone could guide me or maybe show me an example, on how this work sheet should be handled. I am really embarrased by asking but i hope someone will have the understanding to help a struggling biology student.

Thank you for your time.....

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Post by Poison » Sun Mar 12, 2006 8:59 pm

This is not a homework answering forum. Try to do it yourself and ask the points that are not clear.

PS: please do not double post.
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Post by canalon » Sun Mar 12, 2006 10:42 pm

Ok. The answer are rather obvious. On top of the page you have the correspondance between genotypes (GG, Gg etc..) and phenotypes (gray hair, white hair etc).

So for 1 you just look at each trait and make the translation.

For 2 and 3 in each square you make the produce of the crossing of the gametes which corresponds to this cells. ie: GbxGb=GGbb, and you translate that in phenotype, and you count how many cells you have for each phenotype that will give you the frequency of each phenotype (here: n/16)

4 is the same as 2 and 3 but you have to do it by yourself instead of using tables already made. So you have to determine the genotype of each parent (if many genotypes are possible, you will have to treat them independantly) and draw the punnet square. Et voila.

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Post by CrovaxPT » Tue Mar 14, 2006 11:36 am

Hey there. Well you have here a dominance-recessivity exercise. You note that some aspects are dominant to others.

This is a case of dihybridism and you can do it the same way you work on monohybridism, but with 2 letters. Try to do it for yourself and get your doubts here... We'll keep in touch!

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Post by AlyHawthorne » Wed Mar 15, 2006 2:47 am

Note: If you're having trouble coming up with the gametes for a dihybridism cross, use a punnett square for the first parent, then do a separate punnett square for the second parent. Decide which trait will go first, then keep it that way, no matter which one is dominant. Just a helpful tip - some of us can look at it and see which gametes will be formed, but others of us have difficulties with that.

Ex. Parent: AaGg
Gametes: AG, Ag, aG, ag (A goes first, but you can do G if you like)
Punnett Square:
dddA a
g Ag ag

Hope that helps!

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