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18 May 2018

In cross I, we are treating F1 x dp se (cross [b] ) and dp se x F1 (cross [c]) as equivalent crosses, but in Drosophila that is generally a very bad idea! Why is it a bad idea in general and why will we be able to get away with it in cross I? (3 points)

Cross B is (F1 virgin females X dp;se males)

Cross C (dp;se virgin females X F1 males)

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mainLv10

16 Jul 2023

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19 May 2018

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Related questions

3) You have examined the results of the following crosses usingpure-breeding fruit flies.
i) Gray-bodied males Ã ebony-bodied females yield all gray-bodiedflies. The same is true if gray-bodied
females are crossed with ebony-bodied males.
ii) Long-bristled males Ã short-bristled females yield alllong-bristled flies. The same is true if long-bristled
females are crossed with short-bristled males.
iii) Ebony-bodied, short-bristled males Ã gray-bodied,long-bristled females yield all gray-bodied, long
bristled flies.
a) (10 Points) What information concerning body color and bristlelength is provided by crosses (i) and (ii)?
b) (10 Points) Write the genotype for the parents in cross (iii)and the expected genotype of the F1 from.
c) (10 Points) An F1 female from cross (iii) was back-crossed tohis ebony-bodied, short-bristled father. Assuming
independent assortment, write the expected genotype(s) and theproportion of each genotype for the progeny of this
cross.
d) (10 Points) An F1 female and F1 male from cross (iii) were matedto produce an F2. Assuming independent
assortment, what is the probability that a gray-bodied,long-bristled progeny from that cross will be a dihybrid?

coffeemuskrat486

You have four pure-breeding strains of mice that all have white fur. Crosses between brown females from a wild-type strain and white males from your four strains produce only brown progeny, indicating that all four strains carry a recessive mutation that causes white fur. You cross all of the white strains to each other as indicated in the table below, and record the fur color of the offspring.

Mother strain Father strain Progeny

Cross #1 A B brown

Cross #2 A C brown

Cross #3 A D white

Cross #4 C B white

Cross #5 D B brown

Cross #6 D C brown

Cross #7 B A brown females, white males

Cross #8 C A brown females, white males

Cross #9 D A white

Cross #10 B C white

Cross #11 B D brown females, white males

Cross #12 C D brown females, white males

Complete the following table of progeny genotypes from the crosses listed above. You will need as many loci (columns) as there are number of different genes carrying white-fur mutations (this may be more or fewer than three loci). In each row indicate the genotype of the progeny of that cross at all loci. Denote white-fur alleles with w and brown-fur alleles with +. If there are loci where the genotype differs between males and females, list both genotypes and indicate which genotype belongs to each sex.

Cross # locus1 locus2 locus3 ....

1 + +

In a few sentences, describe why some crosses produce all brown offspring, some crosses produce all white offspring, and some produce brown and white offspring. Use the following terms in your answer: complement, fail to complement, X-linked, autosomal.

redyak252

3. Consider a cross between white-eyed female flies and red-eyed male flies. Importantly, the white gene is X-linked. Write out the punnett square here. Be sure to define your allele symbols then indicate the probability (a ratio is fine) of observing any one of the following phenotypes:

a. Red-eyed females _________

b. Red-eyed males _________

c. White-eyed females ________

d. White-eyed males. __________

4. You want to build a double mutant (ab/ab) between two genes, A and B, that are 10 map units apart. You first cross a/a into b/b to create the dihybrid: a+/+b. Next, you do an F1 cross and search the F2 generation for the rare double mutant: ab/ab. What percent of the progeny (offspring) will have the double mutant phenotype in the F2 generation? Show your equation. 5. EXTRA CREDIT. It should be noted that white was not the first sex-linked mutation discovered. In the currant moth Abraxus, DONCASTER and RAYNOR (1906) described a trait called lacticolor segregating among wild females but not among males. How might one explain this?