Homework Clinic
Science Clinic => Biology => Topic started by: londonang on Mar 26, 2020
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A mutant gene that produces brown eyes (bw) is located on chromosome 2 of Drosophila melanogaster, whereas a mutant gene producing bright red eyes, scarlet (st), is located on chromosome 3. Phenotypically, wild-type flies (with dull red eyes), whose mothers had brown eyes and whose fathers had scarlet eyes, were mated. The 800 offspring possessed the following phenotypes: wild type (dull red), white, scarlet (bright red), and brown. Most of the 800 offspring had wild-type eyes, whereas those with white eyes were the least frequent.
(a) Using standard symbolism, diagram the cross from the P generation (brown-eyed mothers scarlet-eyed fathers) and the F1 generation. Be certain to provide the alleles of the mutant genes.
(b) From the information presented above, how many white-eyed flies would you expect in the F2 generation?
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| (a) | P: | bw/bw; st+/st+ | × | bw+/bw+; st/st |
| F1: | bw+/bw; st+/st | × | bw+/bw; st+/st |