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

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

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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a. Bacteriophage P22 was used in generalized transduction experiments to infect the Salmonella typhimurium donor strains described in the table below. The resulting phage lysates were then used to infect the S. typhimurium recipient strains listed in the table. In each cross, a phenotype was selected for one of the three genetic markers studied (str, aceA, thrA), and then replicates were performed to select the corresponding recombinants for the other two markers. The results are given in the following table: Recipient strain Selected phenotype Selected recombinants Donor strain str thrA aceAt thrA str aceA+ strs thrA+ aceA thrA+ str aceA Str Ace+ Str ThrA ThrA+ ThrA ThrA+ Ace Ace+ str: gene involved in streptomycin resistance, aceA: gene involved in the use of acetate as a carbon source, thrA: gene involved in the biosynthesis of threonine. Number 60 40 95 5 10 90 What are the selective media used in these three transduction experiments, on the one hand to obtain the selected…
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:Analyze data. Compare and contrast. Make a drawing.
A prototrophic strain (his" arg" lac') was used as a donor to transform an auxotrophic strain (his arg lac'). Initial transformants are isolated on minimal medium + histidine + arginine + lactose - glucose. i. What genotypes will grow on this medium? ii. These colonies are replicated to minimal medium + histidine, and 50% of the original colonies grow. What genotypes will grow on this medium? iii. The original colonies are also replicated to minimal medium + arginine, and 10% of the colonies grow. What genotypes will grow on this medium? iv. The original colonies are also replicated to minimal medium. No colonies grow. Based on this information, what genotypes will grow on minimal medium + histidine and on minimal medium + arginine? What is the relative gene order for his, arg, and lac? Which two genes are closer? Explain your answer.
Bacteriophage P22 was used in generalised transduction experiments to infect the Salmonella typhimurium donor strains described in the table below. The resulting phage lysates were then used to infect the recipient strains of S. typhimurium recipient strains listed in the table. In each cross, a phenotype was selected for one of the selected for one of the three genetic markers studied (str, aceA, thrA), and were made to select the recombinants corresponding to the other two markers. markers. The results are given in the following table: Strain I donor str thrA aceA thrA str aceA+ Strain recipient strs thrA+ aceA thrA str aceA Phenotype selected Str Ace+ Str recombinants selected ThrA ThrA ThrA ThrA Ace Ace Number 60 40 95 5 10 90 str: gene involved in streptomycin resistance, aceA: gene involved in the use of acetate as a carbon source, thrA: gene involved in threonine biosynthesis. 1) What are the selective media used in these three transduction experiments? to obtain the selected…
Bacteriophage P22 was used in generalized transduction experiments to infect the Salmonella typhimurium donor strains described in the table below. The resulting phage lysates were then used to infect the S. typhimurium recipient strains listed in the table. In each cross, a phenotype was selected for one of the three genetic markers studied (str, aceA, thrA), and then replicates were performed to select the corresponding recombinants for the other two markers. The results are given in the following table: Recipient strain Selected phenotype Selected recombinants Donor strain str thrA aceA+ thrA str aceA+ strs thrA+ aceA thrA+ str aceA Str Ace+ Str ThrA ThrA+ ThrA ThrA+ Ace Ace str: gene involved in streptomycin resistance, aceA gene involved in the use of acetate as a carbon source, thrA: gene involved in the biosynthesis of threonine. Number 60 40 95 5 10 90 Determine the order of the genes and draw a genetic map showing this order
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:Explain how these results are consistent with the idea that thebacterial chromosome is circular?
Two 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.
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.
In Escherichia coli, four different Hfr strains, derived from the same F* strains, were mated with F strains auxotrophic for a number of nutritional requirements (Arg Bio Cys Trp Gal His Lac Mal Xyl Leu Met). Matings were interrupted at various intervals and cells were plated on minimal medium supplemented with particular nutrients to test for gene transfer. The following results show the time of entry for each of the genes in four different Hfr strains. Table 1: Time-of-Entry Mapping Data* Hfr strains Genes lac" his" arg' bio 9. Cys gal" trp' 5 11.5 2.5 mal" xyl" leu met Hfr 1 Hfr 2 Hfr 3 Hfr 4 6.5 3.5 11 15 15 4 6. 17.5 5 14.5 3 20 * The numbers denote the number of minutes elapsed before a gene enters the F cells. Draw a circular map of E. coli chromosome.
A microbial geneticist isolates a new mutation in E. coliand wishes to map its chromosomal location. She usesinterrupted-mating experiments with Hfr strains andgeneralized-transduction experiments with phage P1.Explain why each technique, by itself, is insufficient foraccurate mapping.
When plasmids are isolated from bacterial cells, they may existin a number of forms.a. List the different forms that may be found.b. Which do you think would migrate the fastest and farthest in anelectrophoresis experiment and why?
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?