his-1 and lys-3 are alleles found in baker's yeast that require histidine and lysine for growth, respectively. A cross was made between two haploid yeasts that are his-1 lys-3 and his lys". From the analysis of 900 individual tetrads, the following numbers of tetrads were obtained: GI: 2 spores are his-1 lys +2 spores are his lys-3= 8 G2: 2 spores are his-1 lys-3+ 2 spores are his lys = 512 G3: 1 spore is his-1 lys-3+1 spore is his-1 lys +1 spore is his lys-3 + 1 spore is his* lys = 380 (i) Name the ascus type of each group as P, NP or T. (ii) Are the genes linked? Explain your answer. (iii) If the genes are linked, calculate the distance between the genes.

his-1 and lys-3 are alleles found in baker's yeast that require histidine and lysine for growth, respectively. A cross was made between two haploid yeasts that are his-1 lys-3 and his lys". From the analysis of 900 individual tetrads, the following numbers of tetrads were obtained: GI: 2 spores are his-1 lys +2 spores are his lys-3= 8 G2: 2 spores are his-1 lys-3+ 2 spores are his lys = 512 G3: 1 spore is his-1 lys-3+1 spore is his-1 lys +1 spore is his lys-3 + 1 spore is his* lys = 380 (i) Name the ascus type of each group as P, NP or T. (ii) Are the genes linked? Explain your answer. (iii) If the genes are linked, calculate the distance between the genes.

Biology (MindTap Course List)

11th Edition

ISBN:9781337392938

Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Publisher:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Chapter11: The Basic Principles Of Heredity

Section: Chapter Questions

Problem 11TYU: Individuals of genotype AaBb were mated to individuals of genotype aabb. One thousand offspring were...

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The alleles his-5 and lys-1, found in yeast, result in cells that require histidine and lysine for growth, respectively. A cross was made between two haploid yeast strains that are his-5 lys-1 and his+ lys+. 973 tetrads were analyzed, with the follow pattern: 7 tetrads with 2 his-5 lys+ spores and 2 his+ lys-1 spores 603 tetrads with 2 his-5 lys-1 spores and 2 his+ lys+ spores 363 tetrads with 1 his-5 lys-1 spore, 1 his-5 lys+ spore, 1 his+ lys-1 spores, and 1 his+ lys+ spore Compute the map distance between these two genes using the method that considered double crossovers and the one that does not. Which gives the higher value? Why? What is the frequency of single crossovers between these genes? Explain. Based on the frequency of single-crossovers, how many double crossovers would one expect? Is positive interference occurring?
The alleles his-5 and lys-1, found in yeast, result in cells that require histidine and lysine for growth, respectively. A cross was made between two haploid yeast strains that are his-5 lys-1 and his+ lys+. 973 tetrads were analyzed, with the follow pattern: 7 tetrads with 2 his-5 lys+ spores and 2 his+ lys-1 spores 603 tetrads with 2 his-5 lys-1 spores and 2 his+ lys+ spores 363 tetrads with 1 his-5 lys-1 spore, 1 his-5 lys+ spore, 1 his+ lys-1 spores, and 1 his+ lys+ spore Compute the map distance between these two genes using the method that considered double crossovers and the one that does not. Show your work. Which give the higher value? Why? What is the frequency of single crossovers between these genes? Explain. Based on the frequency of single-crossovers, how many double crossovers would one expect? Is positive interference occurring?
The alleles his-5 and lys-1, found in yeast, result in cells that require histidine and lysine for growth, respectively. A cross was made between two haploid yeast strains that are his-5 lys-1 and his+ lys+. 973 tetrads were analyzed, with the following pattern: 7 tetrads with 2 his-5 lys+ spores and 2 his+ lys-1 spores 603 tetrads with 2 his-5 lys-1 spores and 2 his+ lys+ spores 363 tetrads with 1 his-5 lys-1 spore, 1 his-5 lys+ spore, 1 his+ lys-1 spores, and 1 his+ lys+ spore Compute the map distance between these two genes using the method that considered double crossovers and the one that does not. Show your work. Which give the higher value? Why? What is the frequency of single crossovers between these genes? Explain. Based on the frequency of single-crossovers, how many double crossovers would one expect? Is positive interference occurring?
The alleles his-5 and lys-1, found in baker’s yeast, result in cellsthat require histidine and lysine for growth, respectively. A crosswas made between two haploid yeast strains that are his-5 lys-1and his+ lys+. From the analysis of 818 tetrads, the followingnumbers of tetrads were obtained:2 spores with his-5 lys+ + 2 spores with his+ lys-1 = 42 spores with his-5 lys-1 + 2 spores with his+ lys+ = 5021 spore with his-5 lys-1 + 1 spore with his-5 lys+ + 1 spore withhis+ lys-1 + 1 spore with his+ lys+ = 312A.What is the frequency of single crossovers between these twogenes?B. Based on your answer to part B, how many NPDs are expectedfrom this cross? Explain your answer. Is positive interferenceoccurring?
The alleles his-5 and lys-1, found in baker’s yeast, result in cellsthat require histidine and lysine for growth, respectively. A crosswas made between two haploid yeast strains that are his-5 lys-1and his+ lys+. From the analysis of 818 tetrads, the followingnumbers of tetrads were obtained: 2 spores with his-5 lys+ + 2 spores with his+ lys-1 = 42 spores with his-5 lys-1 + 2 spores with his+ lys+ = 5021 spore with his-5 lys-1 + 1 spore with his-5 lys+ + 1 spore withhis+ lys-1 + 1 spore with his+ lys+ = 312 Compute the map distance between these two genes using firstthe method of calculation that considers double crossovers andthen the one that does not. Which method gives a higher value?Explain why?
One yeast strain carries the alleles lys+ and arg+, whereas another strain has lys-3 and arg-2. The two strains were crossed toeach other, and an ascus obtained from this cross has four spores with the following genotypes: lys+ arg+, lys+ arg-2, lys-3arg+, and lys-3 arg 2. This ascus has a. a parental ditype.b. a tetratype.c. a nonparental ditype.d. either a tetratype or a nonparental ditype.
Imagine that you have done a cross between two strains of yeast, one of which has the genotype A B C and the other a b c, where the letters refer to three closely linked genes in the order given. You examine many tetrads resulting from this cross, and the two tetrads below are found that have atypical scoring patterns. In tetrad I, the spores are A B C, ABC, a B c, and a b c. In tetrad II, the spores are A B C, A b c, a b C, and a b c. Which tetrad or tetrads indicate(s) that gene conversion has occurred AND show(s) that recombination has occurred between genes A and C? O neither tetrads I and II O tetrad II O tetrad I O both tetrads I and II
Neurospora of genotype a + c are crossed withNeurospora of genotype + b +. (Here, + is shorthandfor the wild-type allele.) The following tetrads areobtained (note that the genotype of the four sporepairs in an ascus are listed, rather than listing alleight spores):a + c a b c + + c + b c a b + a + ca + c a b c a + c a b c a b + a b c+ b + + + + + b + + + + + + c + + ++ b + + + + a b + a + + + + c + b +137 141 26 25 2 3a. In how many cells has meiosis occurred to yieldthese data?b. Give the best genetic map to explain these results.Indicate all relevant genetic distances, both betweengenes and between each gene and the centromere.c. Diagram a meiosis that could give rise to oneof the three tetrads in the class at the far right inthe list
A cross between yeast strains ab x AB produces the following unordered tetrads: a. Label each group of tetrads as parental ditypes (PD), non-parental ditypes (NPD), or tetratypes (T). AB AB ab ab 43 6 22 b. Are the genes linked or on separate chromosomes? Why? aB aB Ab Ab Ab AB ab aB c. If the genes are linked determine the distance between them.
The following results are derived from crosses between Neurospora strain xy and strain ++: Tetrad Class 3 4 ху x+ x+ xy ++ ++ ++ +y +y ху +y 25 ++ 3 124 4 (i) Name the ascus type of each class from 1 to 4 as P, NP or T. (ii) Are genes x and y linked? Explain your answer. (iii) If they are linked, determine the map distance between the two genes. If they are unlinked, provide all the information you can about why you draw this conclusion.
An individual heterozygous for a reciprocal translocation possesses the following chromosomes: A B • C D E F G A B • C D V W X R S • T U E F G R S • T U V W X Q. Give the products that result from alternate, adjacent-1, and adjacent-2 segregation.
A yeast geneticist irradiates haploid cells of a strain that is an adenine-requiring auxotrophic mutant, caused by mutation of the gene ade1. Millions of the irradiated cells are plated on minimal medium, and a small number of cells divide and produce prototrophic colonies. These colonies are crossed individually with a wildtype strain. Two types of results are obtained:(1) prototroph × wild type : progeny all prototrophic(2) prototroph × wild type : progeny 75% prototrophic, 25% adenine-requiring auxotrophsa. Explain the difference between these two types of results.b. Write the genotypes of the prototrophs in each case.c. What progeny phenotypes and ratios do you predict from crossing a prototroph of type 2 by the original ade1auxotroph?