Concept explainers
An Hfr strain that is
Duration of conjugation (minutes)
A. Determine the map distance (in minutes) between these two genes.
B. In a previous experiment, it was found that
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Genetics: Analysis and Principles
- An Hfr strain that is leuA+ and thiL+ was mixed with a strain thatis leuA− and thiL−. In the data points shown in the following graph,the conjugation was interrupted at different time points, and thepercentage of recombinants for each gene was determined bystreaking on a medium that lacked either leucine or thiamine.Make a calculation.arrow_forwardAn Hfr strain that is leuA+ and thiL+ was mixed with a strain thatis leuA− and thiL−. In the data points shown in the following graph,the conjugation was interrupted at different time points, and thepercentage of recombinants for each gene was determined bystreaking on a medium that lacked either leucine or thiamine.What information do you know based on the question and your understanding of the topic?arrow_forwardAn Hfr strain that is hisE + and pheA + was conjugated to a strain that is hisE − and pheA −. The conjugation was interrupted at different times, and the percentage of recombinants for each gene was determined by streaking on media that lacked either histidine or phenylalanine. The following results were obtained: A. Determine the map distance (in minutes) between these twogenes.B. In a previous experiment, it was found that hisE is 4 minutesaway from pabB and that PheA is 17 minutes from pabB. Drawa genetic map showing the locations of all three genes.arrow_forward
- In E. coli, four Hfr strains donate the following markers,shown in the order donated:Strain 1: M Z X W CStrain 2: L A N C WStrain 3: A L B R UStrain 4: Z M U R BAll these Hfr strains are derived from the same F+ strain.What is the order of these markers on the circularchromosome of the original F+?arrow_forward) In a conjugation experiment, we used two strains: Hfr: streptomycin sensitive and F-: auxotrophic for isoleucine and threonine, streptomycin resistant. If we interrupt conjugation when only threonine gene has been transferred and spread this mixture on: Minimal media, Minimal media with streptomycin Minimal media with threonine and streptomycin Minimal media with isoleucine and streptomycin LB agar plates with streptomycin On which plates do we expect bacterial growth? Why?arrow_forwardThe 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.arrow_forward
- Three different Hfr donor strains are mixed with separate samples of an F− strain, and the following mapping data are provided from studies of interrupted conjugation: Appearance of genes in F − cells Hfr1: Genes b+ d+ c+ f+ g+ Time* 3 5 16 27 59 Hfr2: Genes e+ f+ c+ d+ b+ Time 6 24 35 46 48 Hfr3: Genes d+ c+ f+ e+ g+ Time 4 15 26 44 58 Construct a genetic map for these genes, indicating their order on the bacterial chromosome and the distances between them.arrow_forwardAn 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 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +arrow_forwardAn interrupted mating study is carried out on Hfr strains 1, 2, and 3. After conjugation is established, a small sample of the mixture is collected every minute for 20 minutes to determine the distance between the genes on the chromosome. Times of entry for each of the three Hfr strains studied in the interrupted mating are provided in parenthesis. The total duration of conjugation (in minutes) is given for each transferred gene. Hfr Strain Genes Transferred Hfr 1 oriT(0) met(2) ala(8) lac(13) gal(17) Hfr 2 oriT(0) met(2) leu(7) thr(10) azi(17) Hfr 3 oriT (0) gal(3) pro(8) trp(14) azi(19) Hfr 4 oriT leu met ala lac Hfr 5 oriT trp azi thr leu a. Use the data to construct a circular map of the bacterium.arrow_forward
- 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.arrow_forwardTwo auxotrophic triple Escherichia coli strains (A: met- phe- ade- val+ bio+ thr+ and B: met+ phe+ ade+ val- bio- thr-) are mixed in LB liquid medium, diluted and then spread on LB solid rich medium. Six colonies are observed: Then, replicates are performed on 6 different media (minimum medium + glucose + indicated substances). The results are shown below. Determine the genotype of the 6 colonies observed. Which ones are from strain A? From strain B? Which hypotheses can explain these results and which one do you prefer? met phe val bio Abbreviations: met ade val thr phe ade bio thr Met: methionine; Phe: phenylalanine; Ade: adenine; Val: valine; Bio: biotin; Thr: threonine.arrow_forwardA series of Hfr strains that have genotype m+ n+ o+ p+ q+ r+ are mixed with an F− strain that has genotype m− n− o− p− q− r−. Conjugation is interrupted at regular intervals and the order of the appearance of genes from the Hfr strain is determined in the recipient cells. The order of gene transfer for each Hfr strain is What is the order of genes on the circular bacterial chromosome? For each Hfr strain, give the location of the F factor in the chromosome and its polarity. Hfr5 m+ q+ p+ n+ r+ o+ Hfr4 n+ r+ o+ m+ q+ p+ Hfr1 o+ m+ q+ p+ n+ r+ Hfr9 q+ m+ o+ r+ n+ p+arrow_forward
- Biology: The Dynamic Science (MindTap Course List)BiologyISBN:9781305389892Author:Peter J. Russell, Paul E. Hertz, Beverly McMillanPublisher:Cengage Learning