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Genetic diagram question!

In co-dominance, I don't get why the symbols we use are different.

eg. C-colour.
R-red, W-white

C^RC^R = red
C^RC^W

Whereas when not dealing with co-dominance, it's just
RR = red
WW = White

Why can't you just do that, why do you need the 'C'?
Or am I just reading too much into this and it's just to show that you're dealing with co-dominance
Reply 1
Original post by ILoveUSA
In co-dominance, I don't get why the symbols we use are different.

eg. C-colour.
R-red, W-white

C^RC^R = red
C^RC^W

Whereas when not dealing with co-dominance, it's just
RR = red
WW = White

Why can't you just do that, why do you need the 'C'?
Or am I just reading too much into this and it's just to show that you're dealing with co-dominance


Well, it is common convention to denote dominant alleles with an upper-case letter and recessive alleles with a lower-case letter. It wouldn't make sense to do this with co-dominant alleles because neither has dominance over the other. The use of "C" for both alleles shows that they are alleles of the same gene, despite having different letters ("r" and "w"). I really wouldn't worry about it if I were you.
Reply 2
Codominance uses, like Ashnard said, same symbols because neither gene is dominant over the other. For instance, in the MN blood group system, if a child inherits I^M and I^N both then his genotype will be I^M*I^N.

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