Two pure bred Drosophila flies are bred. The male fly has stunted antennae with a grey body and the female has normal antennae with a black body. All of the progeny have normal antennae with grey bodies. Diagram the mating of the F1’s with a Punnett square assuming that there is no epistastis and the traits are controlled by two alleles that show simple dominant recessive relationships.
I've already asked this question, but i just cannot verify what they told me. They said:
"For situation #2, you are crossing two traits which is called a dihybrid cross. Let A stand for normal antennae and let 'a' stand for recessive stunted antennae. Let "G" stand for dominant grey bodies and 'g' stand for recessive black. Because all offspring were normal antennae with grey bodies, both of which are dominant traits and NONE of the offspring showed the recessive phenotype, then the male's genotype is aaGG and the females genotype is AAgg. All offspring would get one dominant allele for each trait and all offspring would be heterozygous for both traits.
If you were to take the the F1s and cross two from that falial, you'd end up with the following phenotype ratio: 9 normal antennae w/ grey body : 3 normal antennae with black body : 3 stunted antennae with grey body : 1 stunted antenaee with black body.
Sorry, but I'm not going to do the genotype ratios. All of this was done with a 16 box punnett square."
I am not getting this ratio, nor can I figure out what the genotype would be without getting a smaller punnett square. If anyone can tell me what the punnett square looks like, I'd greatly appreciate it.
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Verified answer
set up a four by four punnet square. Now for example the female will be AAgg and the male aaGG. Set it up like this:
/////////aG aG aG aG
Ag AaGg AaGg
Ag (F1's are all the same)
Ag
Ag
where along the side for each gender you put every possible combination of genotypes. You have 2 possible genotypes for each gene (a and A, g and G) and so you need to use a 4x4 square.
Now take the F1's (AaGg) and put them into a punnet square:
///////AG Ag aG ag
AG AAGG AAGg AaGG AaGg
Ag AAGg AAgg AaGg Aagg
aG AaGG AaGg aaGG aaGg
ag AaGg Aagg aaGg aagg
Now if you count them up you can find that in a cross of two heterozygous genotypes there is a ratio (all dominant trait: one of the traits recessive: the other trait recessive: both traits recessive) of 9:3:3:1. Just memorize the ratio.
That big thing up there is what he meant by a 16 box punnett square.
Hope this helps
Sorry the squares don't come out right, but draw them out
Punnett Square Diagram
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RE:
PUNNETT SQUARE HELP!! Diagram the mating of the F1’s with a Punnett square....?
Two pure bred Drosophila flies are bred. The male fly has stunted antennae with a grey body and the female has normal antennae with a black body. All of the progeny have normal antennae with grey bodies. Diagram the mating of the F1’s with a Punnett square assuming that there is no epistastis...