A geneticist is using a three-point testcross to map three linked Drosophila recessive mutations called a, b, and c, where a is associated with anomalous gait, b is associated with buckled wings, and c is associated with curved bristles. She first crosses homozygous anomalous, buckled flies to homozygous curved flies. Next, she testcrosses the F1 progeny to anomalous, buckled, curved flies. She obtains 1000 progeny distributed as shown. From this data, calculate the map distance between b and c. Testcross progeny phenotype Number curved 281 map distance: m. u. anomalous, buckled 279 wild type 4 anamalous, buckled, curved buckled, curved 128 anomalous 132 anomalous, curved 83 buckled 87

A geneticist is using a three-point testcross to map three linked Drosophila recessive mutations called a, b, and c, where a is associated with anomalous gait, b is associated with buckled wings, and c is associated with curved bristles. She first crosses homozygous anomalous, buckled flies to homozygous curved flies. Next, she testcrosses the F1 progeny to anomalous, buckled, curved flies. She obtains 1000 progeny distributed as shown. From this data, calculate the map distance between b and c. Testcross progeny phenotype Number curved 281 map distance: m. u. anomalous, buckled 279 wild type 4 anamalous, buckled, curved buckled, curved 128 anomalous 132 anomalous, curved 83 buckled 87

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Description: A geneticist is using a three-point testcross to map three linked Drosophila recessive mutations called a, b, and c, where a isassociated with anomalous gait, b is associated with buckled wings, and c is associated with curved bristles. She first cr

Human Biology (MindTap Course List)

11th Edition

ISBN:9781305112100

Author:Cecie Starr, Beverly McMillan

Publisher:Cecie Starr, Beverly McMillan

Chapter20: Chromosomes And Human Genetics

Section: Chapter Questions

Problem 7CT: The following pedigree shows the pattern of inheritance of red-green color blindness in a family....

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A geneticist is using a three‑point testcross to map three linked Drosophila recessive mutations called a, b, and c, where a is associated with anomalous gait, b is associated with buckled wings, and c is associated with curved bristles. She first crosses homozygous anomalous, buckled flies to homozygous curved flies. Next, she testcrosses the F1 progeny to anomalous, buckled, curved flies. She obtains 1000 progeny distributed as shown. From this data, calculate the map distance between b and c. progeny curved 277 anomalous, buckled 283 wild type 5 anamalous, buckled, curved 5 buckled, curved 133 anomalous 127 anomalous, curved 86 buckled 84
Consider the following three autosomal recessive mutations in Drosophila:vestigial wings (v); wild type is long (v+)black body color (b); wildtype is gray (b+)plum eyes (p); wildtype is red (p+)A vestigal, gray, red female (homozygous for all three genes) is crossed with a long wing, black, plum male (homozygous for all three genes). The F1 female progeny are mated with triple homozygous recessive males. Here is the phenotypic data for the F2 progeny:vestigal; gray; red 580long wings; black; plum 592vestigal; black; red 45long; gray; plum 40vestigal; black; plum 89long; gray; red 94vestigal; gray; plum 3long; black; red 5A total of 1448 progeny were counted.Which one of the following values is the approximate distance between the plum eye color and black body color loci?
It is assumed that in Drosophila the following genotypes produce phenotypes. َA- B- = Red color A- bb = Plum color aa B- = Magenta color aa bb = White color The third latent genotype, cc, kills homozygous Plums, but has no effect on other genotypes. Also, genotype C- does not produce a large phenotype. If first-generation Drosophilas are heterozygous for all of these genes and interbreed, what phenotypic ratios are expected in society?
You have a Drosophila line that is homozygous for autosomal recessive alleles a, b, and c, linked in that order. You cross females of this line with males homozygous for the corresponding wild-type alleles. You then cross the F1 heterozygous males with their heterozygous sisters. You obtain the following F2 phenotypes (where letters denote recessive phenotypes and pluses denote wild-type phenotypes): 1364 + + +, 365 a b c, 87 a b +, 84 + + c, 47 a + +, 44 + b c, 5 a + c, and 4 + b +.a. What is the recombinant frequency between a and b? Between b and c? (Remember, there is no crossing over in Drosophila males.)b. What is the coefficient of coincidence?
You have a Drosophila line that is homozygous for autosomal recessive alleles a, b, and c, linked in that order. Youcross females of this line with males homozygous for thecorresponding wild-type alleles. You then cross the F1 heterozygous males with their heterozygous sisters. You obtain the following F2 phenotypes (where letters denoterecessive phenotypes and pluses denote wild-type phenotypes): 1364 + + +, 365 a b c, 87 a b +, 84 + + c,47 a + +, 44 + b c, 5 a + c, and 4 + b +.a. What is the recombinant frequency between a andb? Between b and c? (Remember, there is no crossingover in Drosophila males.)b. What is the coefficient of coincidence?
In Drosophila, white eyes (w) are recessive to red eyes (w+) at one locus and black body (b) is recessive to gray body (b+). A homozygous white eyes, gray bodied female is crossed with a homozygous red eyes, black bodied male to produce the F1 progeny. The F1 progeny are testcrossed and produce the following progeny: White eyes, black body: 212 White eyes, gray body: 288 Red eyes, black body: 308 Red eyes, gray body: 192 Does the evidence indicate that w and b loci are linked? Explain why or why not? If they are linked, what is the map distance between the two loci? If they are not linked, what is the map distance between the two loci? If they are linked, are the allels in the F1 in coupling or repulsion? How do you know? Draw the genotypes of all individuals described in the problem (original parents, F1, testcross, and F2 progeny) using the appropriate notation.
Sepia eyes, spineless bristles, and striped body are three recessive mutations in Drosophila found on chromosome 3. A genetics student crosses a fly homozygous for the alleles encoding sepia eyes, spineless bristles, and striped body with a fly homozygous for the wild-type alleles—encoding red eyes, normal bristles, and solid body. The female progeny are then test-crossed with males that have sepia eyes, spineless bristles, and striped body. Assume that the interference between these genes is 0.2 and that 400 progeny flies are produced by the testcross. Based on the map distances provided in Figure , predict the phenotypes and proportions of the progeny resulting from the test cross.
Vermilion eye color in Drosophila is sex-linked and recessive. What would be the phenotypes of maleand female progenies of a cross between a vermilion female and wild-type (red) male?
The allele b gives Drosophila flies a black body and b+ gives brown, the wild-type phenotype. The allele wx of a separate gene gives waxy wings and wx+ gives non-waxy, the wild-type phenotype. The allele cn of a third gene gives cinnabar eyes and cn+ gives red, the wild-type phenotype. A female heterozygous for these three genes is testcrossed, and 1000 progeny are classified with the following phenotypes. 382 cinnabar 379 black, waxy 69 waxy, cinnabar 67 black 48 waxy 44 black, cinnabar 5 wild type 6 black, waxy, cinnabar Based on this data, what is the correct map of these genes in terms of order and distance?
Three recessive mutations in Drosophila melanogaster, roughoid (ru, small rough eyes), javelin (jv, cylindrical bristles), and sepia eyes (se, dark brown eyes) are linked. A three-point cross was carried out and the following progeny obtained: jv+ ru+ se+ 37 jv+ ru+ se 2 jv+ ru se 14 jv+ ru se+ 146 jv ru se+ 2 jv ru se 35 jv ru+ se 154 jv ru+ se+ 10 a. Determine the order of the genes on the chromosome. b. Determine which progeny contain single crossovers and which contain double crossovers and indicate where among the genes the crossovers occurred. c. Calculate the map distances among the genes. d. Calculate the coefficient of coincidence and interference among the genes
The recessive allele s causes Drosophila to have small wings, and the s+ allele causes normal wings. This gene is known to be X linked. If a small-winged male is crossed with a homozygous wild-type female, what ratio of normal to small-winged flies can be expected in each sex in the F1? If F1 flies are intercrossed, what F2 progeny ratios are expected? What progeny ratios are predicted if F1 females are backcrossed with their father?
Two pure-breeding strains of flies are mated, and the F1 are intercrossed. The first strain has curled wings and black bodies. The second strain has straight wings and brown bodies. The F2 progeny are 271 straight wings with brown bodies, 31 curled wings with black bodies, 94 curled wings with brown bodies and 90 straight wings with black bodies. If the F1 were backcrossed to the straight, wing brown bodied parent, what phenotypes would be produced among the progeny? What would be the proportion of each phenotype?