Phenotypes and proportions

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

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curious1234
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Phenotypes and proportions

Post by curious1234 » Fri Jan 25, 2008 4:51 am

I am trying to answer a question and I'm not sure how the book got the answer they have.

If P and Q loci are 35 mu apart, and PQ / pq is selfed what is the phenotype of the progeny and in what proportion?

I know if you cross PQ/ pq with PQ/ pq you get gamates: PQ, pq the parental and Pq pQ as the recombinants. My book says that you take 1/2(1- 0.35) to get P Q, 1/2 (1 - 0.35) to get pq and 1/2(0.35) is Pq, 1/2(0.35) is pQ.

Why is PQ (1-0.35) when the problem states the distance between P and Q is 35mu ? Why do we calculate 1-0.35 to get 0.65 ??

Also, for the proportion of progeny they say for example that PQ/PQ has F1 genotype of 0.1056. Where does this number come from? I have no idea what numbers they use to come up with this.

Any ideas?

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mith
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Post by mith » Fri Jan 25, 2008 5:06 am

35 mu means 35% are recombinants therefore 65% are parental genotypes. therefore parentals percentalge

PQ + pq = (1-0.35).
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curious1234
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Re: Phenotypes and proportions

Post by curious1234 » Fri Jan 25, 2008 5:07 pm

Thanks!

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lozerface16
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Post by lozerface16 » Sun Feb 10, 2008 6:12 pm

my teacher gave me a take home test and one of the q. is
7. A female calico cat is crossed with a male black cat. What are the phenotypes of the offspring and in what proportion?
:shock:
it makes no sence to me and the test mainly consists of q. like this one! :!:
I do not understand..any of it!!
You were born an original , don't die a copy....

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MrMistery
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Post by MrMistery » Sat Feb 16, 2008 5:08 pm

well you need to know how the gene is transmitted, and if there is complete dominance between the alleles which one is the dominant one.
"As a biologist, I firmly believe that when you're dead, you're dead. Except for what you live behind in history. That's the only afterlife" - J. Craig Venter

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