Study Guide for Campbell Biology
11th Edition
ISBN: 9780134443775
Author: Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Jane B. Reece, Martha R. Taylor, Michael A. Pollock
Publisher: PEARSON
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Chapter 27, Problem 13TYK
O157:H7, a pathogenic strain of E. coli, has over 1,000 genes that are not present in the harmless strain K-12. Many of these genes are associated with phage DNA in the bacterial chromosome. These observations suggest that
- a. this virulent strain has many more R plasmids than does the harmless strain and is resistant to almost all antibiotics.
- b. at least some of these genes were acquired through phage-mediated horizontal gene transfer.
- c. virulence genes appear to have been acquired through conjugation with K-12.
- d. all of the above are correct.
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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.
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 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 27 Solutions
Study Guide for Campbell Biology
Ch. 27 - Fill in the following table with brief...Ch. 27 - Complete the following concept map that summarizes...Ch. 27 - This is a micrograph of the cyanobacterium...Ch. 27 - Prob. 4IQCh. 27 - Prob. 5IQCh. 27 - One might think of prokaryotes as primitive,...Ch. 27 - Prob. 2SYKCh. 27 - Prob. 1TYKFCh. 27 - __________ region in which the prokaryotic...Ch. 27 - __________ common staining technique that...
Ch. 27 - Prob. 4TYKFCh. 27 - Prob. 5TYKFCh. 27 - Prob. 6TYKFCh. 27 - Prob. 7TYKFCh. 27 - Prob. 8TYKFCh. 27 - ___________ use of organisms to remove...Ch. 27 - __________type of respiration that uses molecules...Ch. 27 - The Gram stain distinguishes among bacteria based...Ch. 27 - Prob. 2TYKCh. 27 - Some prokaryotes have specialized internal...Ch. 27 - Prob. 4TYKCh. 27 - Prob. 5TYKCh. 27 - Prob. 6TYKCh. 27 - Prob. 7TYKCh. 27 - Prob. 8TYKCh. 27 - Prob. 9TYKCh. 27 - Prob. 10TYKCh. 27 - Which of the following statements accurately...Ch. 27 - Prob. 12TYKCh. 27 - O157:H7, a pathogenic strain of E. coli, has over...
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