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What proportion is homozygous?

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

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What proportion is homozygous?

Postby buurenfanatic » Mon Feb 02, 2009 12:53 am

A hairy leaved, round ovary plant was selfed and the following progeny were obtained.
360 hairy, round;
113 hairy, elongate;
119 smooth, round
40 smooth, elongate
What proportion of the hairy elongate plants are expected to be true breeding?

Attempt at a solution:

I can see that it is a 9:3:3:1 ratio, but I do not understand if the question is simply asking for the proportion of homozygotes in this progeny or if it is asking for the true breeders in 113 hairy, elongate phenotype?

The solution possibility:
A. 1/3
B. 1/4
C. 1/9
D. 1/16
E. None
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Postby mith » Mon Feb 02, 2009 4:57 am

progeny, given that you get a 9331 ratio, you know that the parents are hetero and from there you're supposed to deduce what is "pure".
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Re: What proportion is homozygous?

Postby Lsulou1985 » Wed Feb 18, 2009 2:53 pm

The genotype of the selfed plant is HR Hr hR hr

HR *HHRR HrRr HhRR HhRr

Hr HHRr *HHrr HhRR Hhrr

hR HhRR HhRr *hhRR hhRr

hr HhRr Hhrr hhRr *hhrr

The progenies with homozygous genotypes are HHRR, HHrr, hhRR and hhrr

There the proportion of progenies with homozygous genotypes is 4/16 i.e. 1/4 (One quarter)
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