In a genetics lab, Kim and Maria infected a samplefrom an E. coli culture with a particular virulent bacteriophage. They noticed that most of the cells werelysed, but a few survived. The survival rate in theirsample was about 1 × 10−4. Kim was sure the bacteriophage induced the resistance in the cells, whileMaria thought that resistant mutants probably alreadyexisted in the sample of cells they used. Earlier, for adifferent experiment, they had spread a dilute suspension of E. coli onto solid medium in a large petri dish,and, after seeing that about 105colonies were growingup, they had replica-plated that plate onto three otherplates. Kim and Maria decide to use these plates totest their theories. They pipette a suspension of thebacteriophage onto each of the three replica plates.What should they see if Kim is right? What shouldthey see if Maria is right?

In a genetics lab, Kim and Maria infected a samplefrom an E. coli culture with a particular virulent bacteriophage. They noticed that most of the cells werelysed, but a few survived. The survival rate in theirsample was about 1 × 10−4. Kim was sure the bacteriophage induced the resistance in the cells, whileMaria thought that resistant mutants probably alreadyexisted in the sample of cells they used. Earlier, for adifferent experiment, they had spread a dilute suspension of E. coli onto solid medium in a large petri dish,and, after seeing that about 105colonies were growingup, they had replica-plated that plate onto three otherplates. Kim and Maria decide to use these plates totest their theories. They pipette a suspension of thebacteriophage onto each of the three replica plates.What should they see if Kim is right? What shouldthey see if Maria is right?

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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Austin Taylor and Edward Adelberg isolated some new strains of Hfr cells that they then used to map several genes in E. coli by using interrupted conjugation . In one experiment, they mixed cells of Hfr strain AB-312, which were xyl+ mtl+ mal+ met+ and sensitive to phage T6, with F− strain AB-531, which was xyl− mtl− mal− met− and resistant to phage T6. The cells were allowed to undergo conjugation. At regular intervals, the researchers removed a sample of cells and interrupted conjugation by killing the Hfr cells with phage T6. The F− cells, which were resistant to phage T6, survivedand were then tested for the presence of genes transferred from the Hfr strain. The results of this experiment are shown in the accompanying graph. On the basis of these data, give the order of the xyl, mtl, mal, and met genes on the bacterial chromosome and indicate the minimum distances between them.
Imagine that you are a student in Alfred Hershey and Martha Chase’s lab in the late 1940s. You are given five test tubes containing E. Coli bacteria infected with T2 bacteriophages that have been labeled with either 32P or 35S. Unfortunately, you forget to mark the tubes and are now uncertain about which tubes is which. You performed their blender experiment and got the following results. Which tube out of these 5 contains E. Coli infected with 32P-labeled phage? Explain your answer.
Austin Taylor and Edward Adelberg isolated some new strains of Hfr cells that they then used to map several genes in Escherichia coli by using interrupted conjugation. In one experiment, the researchers mixed cells of Hfr strain AB‑312, which were xyl+ mtl+ mal+ met+ and sensitive to phage T6, with F− strain AB‑531, which was xyl− mtl− mal− met− and resistant to phage T6. The cells were allowed to undergo conjugation. At regular intervals, the researchers removed a sample of cells and interrupted conjugation by killing the Hfr cells with phage T6. The F− cells, which were resistant to phage T6, survived and were then tested for the presence of genes transferred from the Hfr strain. The results of this experiment are shown in the graph. On the basis of these data, give the order of the xyl, mtl, mal, and met genes on the bacterial chromosome and the minimum distances between them in minutes. The origin of transfer is represented by the red triangle. The distances between genes are not…
In your laboratory, you have an F − strain of E. coli that is resistant to streptomycin and is unable to metabolize lactose, but it can metabolize glucose. Therefore, this strain can grow on media that contain glucose and streptomycin, but it cannot grow on media containing only lactose. A researcher has sent you two E. coli strains in two separate tubes. One strain, let’s call it strain A, has an F factor that carries the genes that are required for lactose metabolism. On its chromosome, it also has the genes that are required for glucose metabolism. However, it is sensitive to streptomycin. This strain can grow on media containing lactose or glucose, but it cannot grow if streptomycin is added to the media. The second strain, let’s call it strain B, is an F − strain. On its chromosome, it has thegenes that are required for lactose and glucose metabolism. StrainB is also sensitive to streptomycin. Unfortunately, when strains A and B were sent to you, the labels had fallen off the…
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 E. coli, the gene bioD+ encodes an enzyme involved in biotin synthesis, and galK+ encodes an enzyme involved in galactose utilization. An E. coli strain that contained wild-type versions of both genes was infected with P1 phage, and then a P1 lysate was obtained. This lysate was used totransduce (infect) a strain that was bioD− and galK−. The cellswere plated on a medium containing galactose as the sole carbonsource for growth to select for transduction of the galK+ gene.This medium also was supplemented with biotin. The resultingcolonies were then restreaked on a medium that lacked biotin tosee if the bioD+ gene had been cotransduced. The following resultswere obtained:What information do you know based onthe question and your understanding of the topic?
In E. coli, the gene bioD+ encodes an enzyme involved in biotin synthesis, and galK+ encodes an enzyme involved in galactose utilization. An E. coli strain that contained wild-type versions of both genes was infected with P1 phage, and then a P1 lysate was obtained. This lysate was used totransduce (infect) a strain that was bioD− and galK−. The cellswere plated on a medium containing galactose as the sole carbonsource for growth to select for transduction of the galK+ gene.This medium also was supplemented with biotin. The resultingcolonies were then restreaked on a medium that lacked biotin tosee if the bioD+ gene had been cotransduced. The following resultswere obtained:What topic in genetics does this question address?
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.
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Imagine that you are a student in Alfred Hershey and Martha Chase’s lab in the late 1940s. You are given five test tubes containing E. coli bacteria infected with T2 bacteriophages that have been labeled with either 32P or 35S. Unfortunately, you forget to mark the tubes and are now uncertain about which were labeled with 32P and which with 35S. You place the contents of each tube in a blender and turn it on for a few seconds to shear off the phage protein coats. You then centrifuge the contents to separate the protein coats and the cells. You check for thepresence of radioactivity and obtain the following results. Which tubes contained E. coli infected with 32P-labeled phage? Explain your answer.