Question

In Drosophila, the gene for white (w) eyes is on the X chromosome and it is...

In Drosophila, the gene for white (w) eyes is on the X chromosome and it is epistatic over brown and scarlet. White eyes can also result by crossing brown-eyed females (bw) with scarlet eyed males (st) (that is, when both mutant alleles are present).

A cross is made between white-eyed females with the genotype w//w (otherwise, homozygous for wild type alleles) and white-eyed males hemizygous for the wild type allele (w+ ).

List the expected: a) Genotypes of the P1 and P2 flies. b) F1 phenotypes and genotypes. 26 c) Expected F2 phenotypic ratios. Show your work.

CONCEPT PROBLEM How can the same phenotype stem from many different genotypes? Explain.

Homework Answers

Answer #1

a) Male and female parents genotype is given XWXW and XWY+ respectively.

b) A cross between the above-mentioned parents,

XWXW   XWY+

F1 genotype, XWXW XWXW   XWY+ XWY+

F1 phenotype = 1, all progeny will be white

c) Parents, XWXW XWY+

Gametes, XW   XW XW Y+

F2generation,  XWXW XWXW   XWY+ XWY+

All F2females and males will be white

The same phenotype can result from different genotypes because a single dominant allele of white is epistatic to other alleles in females and males. Moreover, males are hemizygous for the X-chromosome, so the only allele present on its X-chromosome can determine the X- linked phenotype.

Know the answer?
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Not the answer you're looking for?
Ask your own homework help question
Similar Questions
In Drosophila, the gene for white (w) eyes is on the X chromosome and it is...
In Drosophila, the gene for white (w) eyes is on the X chromosome and it is epistatic over brown and scarlet. White eyes can also result by crossing brown-eyed females (bw) with scarlet eyed males (st) (that is, when both mutant alleles are present).A cross is made between white-eyed females with the genotype w//w (otherwise, homozygous for wild type alleles) and white-eyed males hemizygous for the wild type allele (w+ ). List the expected: a) Genotypes of the P1 and...
In Drosophila, the X-linked recessive mutation vermillion (v) causes bright red eyes, in contrast to the...
In Drosophila, the X-linked recessive mutation vermillion (v) causes bright red eyes, in contrast to the brick-red eyes caused by the wild-type allele. A separate autosomal recessive mutation, brown (bw), causes flies to have brown eyes. Flies with both mutations have no eye pigmentation and are white-eyed. Determine the F1 and F2 phenotypic ratios for each sex from the following crosses: (a) vermillion females X brown males (b) wild-type females X white-eyed males
In Drosophila, the X-linked recessive mutation vermillion (v) causes bright red eyes, in contrast to the...
In Drosophila, the X-linked recessive mutation vermillion (v) causes bright red eyes, in contrast to the brick-red eyes caused by the wild-type allele. A separate autosomal recessive mutation, brown (bw), causes flies to have brown eyes. Flies with both mutations have no eye pigmentation and are white-eyed. Determine the F1 and F2 phenotypic ratios for each sex from the following crosses: (a) vermillion females X brown males (b) wild-type females X white-eyed males
Question text In drosophila (fruit flies): The yellow gene is on the X-chromosome, the gene product...
Question text In drosophila (fruit flies): The yellow gene is on the X-chromosome, the gene product plays a role in body colour. Wild type flies are a light brown/tan in colour, homozygote yellow mutants have a more yellow shaded body colour. We'll use y+ to represent the wild type allele, and y to represent the mutant allele. y+ is dominant to y. The vestigial gene is on chromosome 2. Homozygote vestigial mutants have very short wings, and cannot fly. We'll...
Cross Category 2: P1 - virgin white-eyed females x P2 - sepia-eyed males A) Are the...
Cross Category 2: P1 - virgin white-eyed females x P2 - sepia-eyed males A) Are the genes for white eyes and sepia eyes dominant or recessive? B) Give the genotypes of P1 white-eyed females and P2 sepia-eyed males. Note: remember that two different genes are responsible for the white and sepia phenotypes. C)Based on your answer to the previous question, please provide the expected phenotype and genotype of the F1 flies. Show your work. 16 D)What are the expected F2...
Please answer all the questions, they're related The autosomal recessive allele bw, for brown eyes in...
Please answer all the questions, they're related The autosomal recessive allele bw, for brown eyes in Drosophila interacts with the X-linked recessive allele, v, for vermilion eyes, since flies that are recessive for both genes have white eyes. Wild type flies have red eyes. What eye color phenotypes, in what proportions, would be expected in the progeny from a cross of a white-eyed female and a brown eyed male?  Choose the best answer. Select one: a. all females with brown eyes,...
9. With reference to eye color phenotypes produced by the recessive, autosomal, unlinked brown and scarlet...
9. With reference to eye color phenotypes produced by the recessive, autosomal, unlinked brown and scarlet loci in Drosophila, predict the F1 and F2 results of the following P1 crosses. When both the brown and the scarlet alleles are homozygous, no pigment is produced, and the eyes are white. a.) wild type x white b.) wild type x scarlet c.) brown x white Please show work
The white eyes w gene of Drosophila is located on the X chromosome. A fly will...
The white eyes w gene of Drosophila is located on the X chromosome. A fly will be ‘hemizygous’ for the w gene if it has which karyotype? Group of answer choices XX XXY XY Which of the following determines the correct segregation of X and Y chromosomes during meiosis I in humans (males): Group of answer choices Lack of homology between X and Y Presence of “pseudoautosomal” (PAR) regions shared by X and Y The presence of the SRY gene...
In silkmoths (Bombyx mori), red eyes (re) and white-banded wings (wb) are encoded by two mutant...
In silkmoths (Bombyx mori), red eyes (re) and white-banded wings (wb) are encoded by two mutant alleles that are recessive to those that produce wild-type traits (re+and wb+); these two genes are on the same chromosome. A moth homozygous for red eyes and white-banded wings is crossed with a moth homozygous for the wild-type traits. The F1 have normal eyes and normal wings. The F1 are crossed with moths that have red eyes and white-banded wings in a testcross. The...
If the gene for white eyes (W gene) is located on X chromosome W= allele for...
If the gene for white eyes (W gene) is located on X chromosome W= allele for red (Dominant) w= allele for white The parents are true breeding. Prediction of Reciprocal crosses 1.) Red Female x White Male (show punnet square) Genotype Proportion Female: Male: Phenotype Proportion Female: Male: 2.) White Female x Red Male (show punnet square) Genotype Proportion Female: Male: Phenotype Proportion Female: Male:
ADVERTISEMENT
Need Online Homework Help?

Get Answers For Free
Most questions answered within 1 hours.

Ask a Question
ADVERTISEMENT