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Title: How to do a dihybrid cross in fruit flies Post by: aerodude30 on Nov 13, 2013 I have a homework question here that is confusing me
"In fruit flies the long L allele for wing length is dominant over the short l allele and grey bodied G is dominant over black g. For the two offspring phenotypic ratios below give the genotypes of the P generation 9:3:3:1 and 1:1:1:1 " Any help would be much appreciated Title: Re: How to do a dihybrid cross in fruit flies Post by: Doctor-2-B on Nov 13, 2013 Those phenotypic ratios are:
DD:Dr:rD:rr This first one corresponds to a heterozygous parental cross of LlGg x LlGg The second one corresponds to a parental cross of LlGg x llgg You sorta have to memorize that a heterozygous self-cross results in a 9:3:3:1 ratio (assuming no epistasis or other anomalies) and to get a 1:1:1:1 ratio, you have to have at least one homozygous recessive for both alleles and one heterozygous for both alleles. Title: Re: How to do a dihybrid cross in fruit flies Post by: aerodude30 on Nov 14, 2013 I can definitely see what your saying but what is the genotype of the P generation exactly? I understand the punnett square cross of it really well and how you got the 9:3:3:1 and 1:1:1:1 ratios would i just list all the answers in the punnett square?
Title: Re: How to do a dihybrid cross in fruit flies Post by: Doctor-2-B on Nov 14, 2013 Content hidden
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