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True-Breeding Crosses - HELP!!!

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

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True-Breeding Crosses - HELP!!!

Postby jduecker84 » Thu Mar 24, 2011 8:37 pm

Here's the question: A true-breeding red snapdragon was crossed to a true-breeding white snapdragon. The F1 progeny were red. When the F1 was selfed, the following F2 progeny were observed: 1850 red, 670 pink, and 831 white totalling 3351 individuals.

Is this complete dominance of the red?

For the F1 generation, I crossed C/C x c/c (C/C = red & c/c = white) and got the following:
C C
c Cc Cc
c Cc Cc so this would make the F1 progeny all red?

and then to self the F1 would be a cross of C/c x C/c ??
C c
C CC Cc
c Cc cc it just doesn't look right for the number of offspring that occurred. The C/c (pink) has a ratio than the numbers show and they just don't add up. Am I missing something?

Thanks
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Postby canalon » Thu Mar 24, 2011 10:02 pm

You are obviously missing something.
In your original cross you have C/c as red and then in the self-cross you consider C/c as pink...

Have you consider revising your hypothesis about the mode of inheritance?
Patrick

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any proof. (Ashley Montague)
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