Genetics: Analysis and Principles
6th Edition
ISBN: 9781259616020
Author: Robert J. Brooker Professor Dr.
Publisher: McGraw-Hill Education
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Chapter 7, Problem 12EQ
Let’s suppose a new strain of P1 phage has been identified that packages larger pieces of the E. coli chromosome. This P1 strain packages pieces of the E. coli chromosome that are 5 minutes long. If two genes are 0.7 minute apart along the E. coli chromosome, what would be the cotransduction frequency using a normal strain of P1 and using the new strain of P1 that packages larger pieces? What would be the experimental advantage of using this new P1 strain?
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In Hershey-Chase experiment, bacteriophages protein coats were tagged with radioactive isotope S-32. These phages were used to infect E. coli cells and the cells were further centrifuged to form pellets.
Why was the radioactivity level of S-32 found greater outside the cells compared to the E. coli cell pellets? Explain briefly.
If the experiment is repeated in the same manner but this time the phage protein coats are labelled with isotope X and the phage DNA with isotope Y, which isotope’s radioactivity will be found in greater amounts in the E. coli cell pellets after centrifugation? Explain briefly.
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.
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…
Chapter 7 Solutions
Genetics: Analysis and Principles
Ch. 7.1 - 1. A form of genetic transfer that involves the...Ch. 7.2 - 1. A bacterial cell with an F factor conjugates...Ch. 7.2 - 2. Which of the following is a type of plasmid?...Ch. 7.3 - 1. With regard to conjugation, a key difference...Ch. 7.3 - 2. In mapping experiments, ______ strains are...Ch. 7.4 - Prob. 1COMQCh. 7.4 - Cotransduction may be used to map bacterial genes...Ch. 7.5 - Prob. 1COMQCh. 7.5 - Prob. 2COMQCh. 7.6 - 1. Which of the following is an example of...
Ch. 7 - 1. The terms conjugation, transduction, and...Ch. 7 - Prob. 2CONQCh. 7 - If you mix together an equal number of F+ and F...Ch. 7 - What is the difference between an F+ and an Hfr...Ch. 7 - 5. What is the role of the origin of transfer...Ch. 7 - 6. What is the role of sex pili during...Ch. 7 - Prob. 7CONQCh. 7 - Prob. 8CONQCh. 7 - Prob. 9CONQCh. 7 - 10. What is cotransduction? What determines the...Ch. 7 - Prob. 11CONQCh. 7 - Prob. 12CONQCh. 7 - Describe the steps that occur during bacterial...Ch. 7 - Prob. 14CONQCh. 7 - Prob. 15CONQCh. 7 - Antibiotics such as tetracycline, streptomycin,...Ch. 7 - Prob. 1EQCh. 7 - 2. In the experiment of Figure 7.1, Lederberg and...Ch. 7 - Explain how a U-tube apparatus can distinguish...Ch. 7 - Prob. 4EQCh. 7 - 5. In a conjugation experiment, what is meant by...Ch. 7 - In your laboratory, you have an F strain of E....Ch. 7 - 7. As mentioned in question 2 of More Genetic...Ch. 7 - An Hfr strain that is hisE+ and pheA+ was mixed...Ch. 7 - Acridine orange is a chemical that inhibits the...Ch. 7 - Prob. 10EQCh. 7 - Prob. 11EQCh. 7 - Lets suppose a new strain of P1 phage has been...Ch. 7 - If two bacterial genes are 0.6 minute apart on the...Ch. 7 - 14. In a cotransduction experiment involving P1,...Ch. 7 - Prob. 15EQCh. 7 - Prob. 16EQCh. 7 - 1. Discuss the advantages of the genetic analysis...Ch. 7 - Prob. 2QSDC
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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 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.arrow_forwardIn recombination studies of the rII locus in phage T4, what is the significance of the value determined by calculating phage growth in the K12 versus the B strains of E. coli following simultaneous infection in E. coli B? Which value is always greater?arrow_forwardIn 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 genearrow_forward
- 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.arrow_forwardIn 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?arrow_forwardIn 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?arrow_forward
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