. a. You want to perform an interrupted-mating mappingwith an E. coli Hfr strain that is Pyr+, Met+, Xyl+,Tyr+, Arg+, His+, Mal+, and Strs. Describe anappropriate bacterial strain to be used as theother partner in this mating.b. In an Hfr × F− cross, the pyrE gene enters therecipient in 5 minutes, but at this time point thereare no exconjugants that are Met+, Xyl+, Tyr+,Arg+, His+, or Mal+. The mating is now allowed toproceed for 30 minutes and Pyr+ exconjugants areselected. Of the Pyr+ cells, 32% are Met+, 94% areXyl+, 7% are Tyr+, 59% are Arg+, 0% are His+, and71% are Mal+. What can you conclude about theorder of the genes?

. a. You want to perform an interrupted-mating mappingwith an E. coli Hfr strain that is Pyr+, Met+, Xyl+,Tyr+, Arg+, His+, Mal+, and Strs. Describe anappropriate bacterial strain to be used as theother partner in this mating.b. In an Hfr × F− cross, the pyrE gene enters therecipient in 5 minutes, but at this time point thereare no exconjugants that are Met+, Xyl+, Tyr+,Arg+, His+, or Mal+. The mating is now allowed toproceed for 30 minutes and Pyr+ exconjugants areselected. Of the Pyr+ cells, 32% are Met+, 94% areXyl+, 7% are Tyr+, 59% are Arg+, 0% are His+, and71% are Mal+. What can you conclude about theorder of the genes?

Biology: The Dynamic Science (MindTap Course List)

4th Edition

ISBN:9781305389892

Author:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Publisher:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Chapter17: Bacterial And Viral Genetics

Section: Chapter Questions

Problem 1ITD

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By conducting conjugation experiments between Hfr and recipientstrains, Wollman and Jacob mapped the order of many bacterialgenes. Throughout the course of their studies, they identified severaldifferent Hfr strains in which the F-factor DNA had been integratedat different places along the bacterial chromosome. A sample of theirexperimental results is shown in the table:Draw a map that shows the order of genes and the locations ofthe origins of transfer among these different Hfr strains?
In a generalized-transduction experiment, phages arecollected from an E. coli donor strain of genotype cys+leu+ thr+ and used to transduce a recipient of genotypecys- leu- thr-. Initially, the treated recipient populationis plated on a minimal medium supplemented with leucine and threonine. Many colonies are obtained.a. What are the possible genotypes of these colonies?b. These colonies are then replica plated onto threedifferent media: (1) minimal plus threonine only, (2)minimal plus leucine only, and (3) minimal. Whatgenotypes could, in theory, grow on these three media?c. Of the original colonies, 56 percent are observed togrow on medium 1, 5 percent on medium 2, and nocolonies on medium 3. What are the actual genotypes ofthe colonies on media 1, 2, and 3?d. Draw a map showing the order of the three genes andwhich of the two outer genes is closer to the middle gene
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.What is the map distance (in minutes) between these two genes?
By conducting conjugation experiments between Hfr and recipientstrains, Wollman and Jacob mapped the order of many bacterialgenes. Throughout the course of their studies, they identified severaldifferent Hfr strains in which the F-factor DNA had been integratedat different places along the bacterial chromosome. A sample of theirexperimental results is shown in the following table:What information do you know based on the question and your understanding of the topic?
By conducting conjugation experiments between Hfr and recipientstrains, Wollman and Jacob mapped the order of many bacterialgenes. Throughout the course of their studies, they identified severaldifferent Hfr strains in which the F-factor DNA had been integratedat different places along the bacterial chromosome. A sample oftheir experimental results is shown in the following table: A. E xplain how these results are consistent with the idea that thebacterial chromosome is circular.B. Draw a map of the bacterial chromosome that shows the orderof genes and the locations of the origins of transfer among thesedifferent Hfr strains.
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.What information do you know based on the question and your understanding of the topic?
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+?
. An Hfr+ strain is used to map three genes: ala, leu, and thr in an interrupted mating experiment. Hfr/ala+, leu+, thr+, camS x F-/ala-, leu-, thr-, camR The cross is initiated at time = 0, and at various times, the mating mixture is plated on three types of medium. Each plate contains minimal medium with chloramphenicol and the amino acids as listed in the table. The data represents the number of colonies growing on each plate. Time of interruption Nutrients added 5 min 10 min 15 min 20 min alanine, leucine 8 21 58 85 leucine, threonine 0 3 19 46 alanine, threonine 0 0 7 16 Based on these data, what is the order of gene transfer relative to one another and to the F-factor.
You co-culture the following bacterial strains: an Hfr prototroph and an F- auxotroph for the genes mal, met, mtl, and xyl. You interrupt conjugation at various time points and place the mixtures on media plates lacking each of the nutrients. Based on the results shown on the right, what is the order of these four genes along the bacterial chromosome? Explain your reasoning.
Four Hfr strains are derived from an F+ strain of E. Coli to serve as donors for an interrupted-mating experiment. Use the time-table and partial map of the F+ strain (shown below) to determine the genes’ respective positions. Keep in mind that the map distances are NOT proportional, only the FIRST 5 markers are indicated per strain, and the entry times, recorded in minutes, are in parentheses. Transferred genes represent wild-type alleles. Based on the data, which gene can be located at position 5 on the map?
As mentioned in question 2 of More Genetic TIPS, origins oftransfer can be located in many different places on a bacterial chromosome,and their direction of transfer can be clockwise or counterclockwise.Let’s suppose a researcher conjugated six differentHfr strains that were thr + leu + tons str r azis lac + gal + pro + met +to an F − strain that was thr − leu − tonr str s azir lac − gal − pro −met −, and obtained the following results: Draw a map of the circular E. coli chromosome that shows thelocations and orientations of the origins of transfer in these six Hfrstrains.
For bacteria that are F+, Hfr, F', and F- answer the following. a. Describe the state of the F factor. b. Which of these cells are donors? Which is the recipient? c. Which of these donors can convert exconjugants to a donor state? d. Which of these donors can transfer a donor gene to exconjugants? e. Describe the results of conjugation (i.e., changes in the recipient and the exconjugant) that allow detection of the state of the F factor in a donor strain. f. Describe a "partial diploid" and how it originates.