Phenotypically wild-type F1 female Drosophila, whose mothers had purple eyes (pr) and fathers had curved wings (cw), produced the following offspring when crossed to homozygous curved-wings and purple eyed males:   Phenotype                         Number Purple-curved wing          220 wild-type                           200 purple                               770 curved wing                      810                              Total: 2000   Compute the map distance between the purple and curved wing loci.单项选择题

A

2 map units

B

77 map units

C

4 map units

D

21 map units

E

11 map units

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Question textA Drosophila female heterozygous for two satellite DNA markers A and B (genotype A1 A2; B1 B2) was crossed with a Drosophila male homozygous for a different allele for each marker (genotype A3 A3; B3 B3). 600 progeny were genotyped for the two markers and the following numbers in each class were obtained:A1 A3; B1 B3 30A1 A3; B2 B3 270A2 A3; B2 B3 30A2 A3; B1 B3 270Fill in the gaps in the following sentences, providing the appropriate word, allele or whole number.a) If markers A and B were not linked, Answer 1 Question 13[input] flies would have been expected in each of the four classes. Provide answer as a numeral e.g. ‘1' not 'one'b) In the double heterozygote female parent, the A2 allele would have been on the same chromosome as the Answer 2 Question 13[input] allele.c) The map distance between markers A and B isAnswer 3 Question 13[input] (numeral) Answer 4 Question 13[input] (provide appropriate units)Provide answer as a numeral e.g. ‘1' not 'one'

Question text In the pedigree shown below, the mother and two children have an autosomal dominant disorder for which the gene has not been identified. The disorder has previously been mapped to chromosome 5, and to further map the disease gene, the individuals in this pedigree have been scored for alleles for five different micro-satellite marker loci on this chromosome, called A, B, C, D and E. These markers are shown in the table below in the order they are already known to be located on the chromosome. The mother’s full genotype is shown in the table as two columns, with the different columns indicating the specific combination of alleles present on each of her two homologous chromosomes (left and right). For the children, only the alleles inherited from their mother (determined previously) are shown. a. Fill in the table below, indicating for each child whether they have inherited a parental or recombinant combination of alleles from their mother. (2 marks) [table] Individual | Parental or Recombinant II-1 | Answer 1 Question 10 ParentalRecombinant II-2 | Answer 2 Question 10 ParentalRecombinant II-3 | Answer 3 Question 10 ParentalRecombinant II-4 | Answer 4 Question 10 ParentalRecombinant II-5 | Answer 5 Question 10 ParentalRecombinant II-6 | Answer 6 Question 10 ParentalRecombinant [/table] b. Which of the mother’s homologous chromosomes (left or right) carries the disease allele? Answer 7 Question 10[select: , Left, Right] (1 mark) c. Between which two markers is the disease gene located? Answer 8 Question 10[select: , A and B, B and C, C and D, D and E] (2 marks) d. The mother is pregnant with a seventh child and prenatal tests show that the fetus has inherited A7 B1 C5 D3 and E1 from the mother. What is the probability that this child will also have the dominant disorder given new information showing that the disease locus is 20 map units from the nearest marker on the left and 10 map units from the nearest marker on the right? Enter answer to 2 decimal places. Answer 9 Question 10[input] (1 mark)

Question textUse the following information to answer questions below In Drosophila the two X- linked genes, yellow body (y, y+ alleles) and vermillion eyes (v, v+ alleles) are 30 map units apart, and a third X-linked gene, singed bristles (s, s+ alleles), is 20 map units from yellow and 10 map units from vermillion. True-breeding females that are yellow, singed and vermillion were crossed with true-breeding wild type males and the F1 consisted of wild type females and yellow, singed and vermillion males. The F1 females were then testcrossed. a. Enter the genotype of both the F1 females and the test cross males, clearly indicating the gene order along the chromosome. Start with the y allele, follow by s and v alleles. Use these notations: "a+" for dominant alleles and "a" for recessive alleles . Do NOT leave spaces. Use the forward slash "/" to separate chromosomes. Use "Y" for the Y chromosome. For the X chromosome, just give the alleles for each gene, do NOT include X in your notation. (e.g. ab+c/Y) Genotype of F1 females = Answer 1 Question 9[input] Genotype of test cross males = Answer 2 Question 9[input] (2 marks) b. In the following table, indicate the genotypes of the eight expected gametes produced by the F1 females, matching each with the correct description of parental, recombinant or double recombinant gametes given in the right-hand column. Start with the y allele. Do NOT leave spaces. Just give the alleles for each gene, do NOT include X in your notation (e.g. ab+c ). [table] F1 female Gamete Genotypes | Parental or Recombinant or double recombinant Answer 3 Question 9 | parental Answer 4 Question 9 | parental Answer 5 Question 9 | recombinant Answer 6 Question 9 | recombinant Answer 7 Question 9 | recombinant Answer 8 Question 9 | recombinant Answer 9 Question 9 | double recombinants Answer 10 Question 9 | double recombinants [/table] (3 marks) c. Assuming no interference, what is the expected frequency of double crossovers between the two outer genes, either side of the middle gene? Provide a numerical answer to maximum two decimal places if needed. Answer 11 Question 9[input] (1 mark) d. If amongst a total progeny of 1000, 8 progeny were the result of double crossovers between the two outer genes, either side of the middle gene, give the following values: (i) the coefficient of coincidence = Answer 12 Question 9[input] Provide a numerical answer to maximum two decimal places if needed. (ii) the interference value = Answer 13 Question 9[input] Provide a numerical answer to maximum two decimal places if needed. (2 marks)

Question textA true-breeding Drosophila strain (P1) with blistered wings (b) was crossed with a true-breeding line of flies (P2) with ebony bodies (e). The F1 were phenotypically wild type. F1 females were testcrossed, and the F2 testcross progeny obtained are: F2 phenotype number Wild type 50 blistered 450 ebony 450 blistered, ebony 50 total 1000 a. Using the b+/b and e+/e gene notation (where + is the dominant allele), give the following genotypes, indicating clearly the arrangement of the alleles on the homologous chromosomes (e.g., ??/??). When entering your answers: 1) Do not leave spaces; 2) separate homologous chromosomes with a forward slash i.e. / P1 genotype Answer 1 Question 8[input] P2 genotype Answer 2 Question 8[input] F1 genotype Answer 3 Question 8[input] (1 mark) b. In the F1 female, are the alleles in coupling or repulsion phase? Answer 4 Question 8[select: , coupling, repulsion] phase (1 mark) c. What is the map distance between the blistered and ebony genes? Answer 5 Question 8[input] cM Give a numerical answer, do not include units (1 mark)

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