Microbiology: An Evolving Science (Fourth Edition)
4th Edition
ISBN: 9780393615098
Author: John W. Foster, Joan L. Slonczewski
Publisher: W. W. Norton & Company
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Chapter 9.4, Problem 2TQ
Summary Introduction
To review:
The advantages of mutator strains for the growth of pathogens.
Introduction:
Pathogenesis is the process of development of diseases in an individual. Pathogens have the ability to infect healthy cells. However, in the clinical samples of bacteria, it is reported that there is more mutant strain present than the reference strains. This shows that the cells containing mutator strain will acquire diseases more frequently than normal cells.
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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…
Two mutations that affect plaque morphology in phages (a− and b −) have been isolated. Phages carrying both mutations (a− b−) are mixed with wild-type phages (a+ b+) and added to a culture of bacterial cells. Once the phages have infected and lysed the bacteria, samples of the phage lysate are collected and cultured on plated bacteria. The following numbers of plaques are observed: Plaque phenotype Number a+ b+ 2043 a+ b− 320 a− b+ 357 a− b− 2134 What is the frequency of recombination between the a and b genes?
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 9 Solutions
Microbiology: An Evolving Science (Fourth Edition)
Ch. 9.1 - Prob. 1TQCh. 9.1 - Prob. 2TQCh. 9.1 - Prob. 3TQCh. 9.1 - Prob. 4TQCh. 9.2 - Prob. 1TQCh. 9.3 - Prob. 1TQCh. 9.4 - Prob. 1TQCh. 9.4 - Prob. 2TQCh. 9.5 - Prob. 1TQCh. 9.6 - Prob. 1TQ
Ch. 9 - Prob. 1RQCh. 9 - Prob. 2RQCh. 9 - Prob. 3RQCh. 9 - Prob. 4RQCh. 9 - Prob. 5RQCh. 9 - Prob. 6RQCh. 9 - Prob. 7RQCh. 9 - Prob. 8RQCh. 9 - Prob. 9RQCh. 9 - Prob. 10RQCh. 9 - Prob. 11RQCh. 9 - Prob. 12RQCh. 9 - Prob. 13RQCh. 9 - Prob. 14RQCh. 9 - Prob. 15RQCh. 9 - Prob. 16RQCh. 9 - Prob. 1TQCh. 9 - Prob. 2TQCh. 9 - Prob. 3TQCh. 9 - Prob. 4TQCh. 9 - Prob. 5TQCh. 9 - Prob. 6TQ
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