A cross is made between two E. coli strains: Hfr arg+ bio* leu* XF arg bio leu¯. Interrupted mating studies show that arg+ enters the recipient last, and so arg+ recombinants are selected on a medium containing bio and leu only. These recombinants are tested for the presence of bio+ and leu*. The following numbers of individuals are found for each genotype: arg+ bio+ leu+ 320 arg bio+ leu 8 arg+ bio leu+ 0 arg bio leu-48

A cross is made between two E. coli strains: Hfr arg+ bio* leu* XF arg bio leu¯. Interrupted mating studies show that arg+ enters the recipient last, and so arg+ recombinants are selected on a medium containing bio and leu only. These recombinants are tested for the presence of bio+ and leu*. The following numbers of individuals are found for each genotype: arg+ bio+ leu+ 320 arg bio+ leu 8 arg+ bio leu+ 0 arg bio leu-48

Human Anatomy & Physiology (11th Edition)

11th Edition

ISBN:9780134580999

Author:Elaine N. Marieb, Katja N. Hoehn

Publisher:Elaine N. Marieb, Katja N. Hoehn

Chapter1: The Human Body: An Orientation

Section: Chapter Questions

Problem 1RQ: The correct sequence of levels forming the structural hierarchy is A. (a) organ, organ system,...

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DNA obtained from the indicated donor strains is used to TRANSFORM the indicated recipient strains. The resulting progeny are plated on minimal medium so that only wild-type recombinants are scored. The number of wild-types for each cross is given in the chart below. donor donor arg+ val- ser- val+ ser- arg- val- ser+ val- ser+ arg+ val- ser- O valine recipient recipient none of these. O arginine arg- val+ ser+ arg+ val- ser+ Which locus is closest to serine? arg+ val+ ser- wild-types wild-types 70 98 0 2 arg- arg-
DNA obtalned from the indicated donor strains is used to TRANSFORM the indicated recipient strains. The resulting progeny are plated on minimal medium so that only wild- type recombinants are scored. The number of wild-types for each cross is given in the chart below. What is the order of the genes? Donor Recipient wid type colonies a-b- c+ a+ b+ c- 273 a- b+ c- a+ b-c+ 462 a- b+ C+ a+ b-c- 2 a b- C+ a- b+ c+ O 4-b-c a-o-b b-a-c cannot be determined Question 18 of 26
An Hfr strain of E. coli that is pro * thr leu * lac was "mated" with an F- strain that is pro thr leu lac. Conjugation was interrupted at 10, 13, 17, and 21 minutes with a kitchen blender, and the % occurrence of donor alleles in F- recombinants was determined at each time point (by replica plating cells on minimal media plates that lacked proline, threonine, leucine, or lactose). The data shown below were obtained. % occurrence pro" % occurrence thr* % occurrence leu* % occurrence lac+ Minutes phenotype phenotype phenotype phenotype 10 6. 13 318 1 20 17 41 11 2 29 21 45 18 10 36 What is the order of these four genes on the bacterial chromosome, starting from the origin? Please write your answer as genes separated by dashes, e.g., thr-leu-lac-pro.
E. coli strain B (permissive) were co-infected with rlla and rllb mutant phage T4. Progeny were plated in a dilution series with the following results: Lawn Dilution Number of plaques Strain B 10-6 10 Strain K 10-4 What is the recombination frequency? Remember that the readout is viability and you cannot see the inviable progeny. Answer:
An Hfrstrain that is a *b*c*d* e*f* g *h* is mated with an F strain that is a b e d e f gh. The mating is interrupted at 5 minutes interval, and the genotypes of the F recombinants are determined. The results obtained are tabulated in Table 2. Draw the map of the Hfrchromosome and indicate the position of the origin of transfer, the direction of the transfer and the minutes between genes. Table 2:Entry time of Hfr chromosome into recipient cell. Time a d e f h 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
Why are the recombinants produced from an Hfr * F- cross rarely, if ever, F+?
A bacterial strain with genotype his− leu− thr− is transformed with DNA from a strain that is his+ leu+ thr+. A few leu+ thr+ cells and a few his+ thr+ cells are found, but no his+ leu+ cells are observed. Which genes are farthest apart?
A particular Hfr strain normally transmits the pro+marker as the last one in conjugation. In a cross of thisstrain with an F− strain, some pro+ recombinants are recovered early in the mating process. When these pro+cells are mixed with F−cells, the majority of the F− cellsare converted into pro+ cells that also carry the F factor.Explain these results.
The following two strains of E. coli are crossed with each other: Hfr pan* thi* ala* and F¯pan¯ thi¯ ala¯ It was shown that the pan marker entered last in interrupted conjugation experiments. By spreading the bacteria from these experiments on different selection media, the following results (in number of colonies) were obtained: MM + Gluc IM + Gluc + ala MM + Gluc + thi MM + Gluc + thi + ala 280 281 286 339 Give the number of each phenotypic class and justify your answer. Determine the order of the genes. What are the genetic distances between the different loci? Abbreviations: Gluc: glucose; Ala: alanine; Thi: thiamine; Pan: pantothenic acid.
Four E. coli strains of genotype a+ b- are labeled 1, 2, 3, and 4. Four strains of genotype a- b+ are labeled 5, 6, 7, and 8. The two genotypes are mixed in all possible combinations and (after incubation) are plated to determine the frequency of a+ b+ recombinants. The following results are obtained, where M = many recombinants, L = low numbers of recombinants, and 0 = no recombinants:On the basis of these results, assign a sex type (either Hfr, F+, or F-) to each strain.
An Hfr strain that is hisE+ and pheA+ was mixed with a strain thatis hisE− and pheA−. The conjugation was interrupted and the percentageof recombinants for each gene was determined by streakingon a medium that lacked either histidine or phenylalanine. Thefollowing results were obtained:Determine the map distance (in minutes) between these twogenes.
An Hfr strain that is hisE+ and pheA+ was mixed with a strain thatis hisE− and pheA−. The conjugation was interrupted and the percentageof recombinants for each gene was determined by streakingon a medium that lacked either histidine or phenylalanine. Thefollowing results were obtained:It was found that hisE is 4 minutes away from pabB. The gene pheA was shown to be 17 minutes from pabB. Draw a genetic map describing the locations of all three genes.