Genetics: From Genes to Genomes
6th Edition
ISBN: 9781259700903
Author: Leland Hartwell Dr., Michael L. Goldberg Professor Dr., Janice Fischer, Leroy Hood Dr.
Publisher: McGraw-Hill Education
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Chapter 14, Problem 23P
Starting with an F- strain that was prototrophic (that is, had no auxotrophic mutations) and Strs, several independent Hfr strains were isolated. These Hfr strains were mated to an F- strain that was Strr Arg- Cys- His- Ilv- Lys- Met- Nic- Pab- Pyr- Trp-. Interrupted-mating experiments showed that the Hfr strains transferred the wild-type alleles in the order listed in the following table as a function of time. The time of entry for the markers within parentheses could not be distinguished from one another.
| a. | From these data, derive a map of the relative position of these markers on the bacterial chromosome. Indicate with labeled arrows the position and orientation of the integrated F plasmid for each Hfr strain. |
| b. | To determine the relative order of the trp, pyr, and cys markers and the distances between them, HfrB was mated with the F- strain long enough to allow transfer of the nic marker, after which Trp+ recombinants were selected. The unselected markers pyr and cys were then scored in the Trp+ recombinants were selected. The unselected markers pyr and cys were then scored in the Trp+ recombinants, yielding the following results: |
Draw a map of the trp, pyr, and cys markers relative to each other. (Note that you cannot determine the order relative to the nic or his genes using these data.) Express map distances between adjacent genes as the frequency of crossing-over between them.
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T. Miyake and M. Demerec examined proline-requiring mutations in the bacterium Salmonella typhimurium (). On the basis of complementation testing, they found four proline auxotrophs: proA, proB, proC, and proD. To determine whether proA, proB, proC, and proD loci were located close together on the bacterial chromosome, they conducted a transduction experiment. Bacterial strains that were proC+ and had mutations at proA, proB, or proD were used as donors. The donors were infected with bacteriophages, and progeny phages were allowed to infect recipient bacteria with genotype proC− proA+ proB+ proD+. The recipient bacteria werethen plated on a selective medium that allowed only proC+ bacteria to grow. After this, the proC+ transductants were plated on selective media to reveal their genotypes at the other three pro loci. The following results were obtained:
Q.Which genotypes represent single transductants and which represent cotransductants?
T. Miyake and M. Demerec examined proline-requiring mutations in the bacterium Salmonella typhimurium (). On the basis of complementation testing, they found four proline auxotrophs: proA, proB, proC, and proD. To determine whether proA, proB, proC, and proD loci were located close together on the bacterial chromosome, they conducted a transduction experiment. Bacterial strains that were proC+ and had mutations at proA, proB, or proD were used as donors. The donors were infected with bacteriophages, and progeny phages were allowed to infect recipient bacteria with genotype proC− proA+ proB+ proD+. The recipient bacteria werethen plated on a selective medium that allowed only proC+ bacteria to grow. After this, the proC+ transductants were plated on selective media to reveal their genotypes at the other three pro loci. The following results were obtained:
Q.Is there evidence that proA, proB, and proD are located close to proC? Explain your answer.
T. Miyake and M. Demerec examined proline-requiring mutations in the bacterium Salmonella typhimurium (). On the basis of complementation testing, they found four proline auxotrophs: proA, proB, proC, and proD. To determine whether proA, proB, proC, and proD loci were located close together on the bacterial chromosome, they conducted a transduction experiment. Bacterial strains that were proC+ and had mutations at proA, proB, or proD were used as donors. The donors were infected with bacteriophages, and progeny phages were allowed to infect recipient bacteria with genotype proC− proA+ proB+ proD+. The recipient bacteria werethen plated on a selective medium that allowed only proC+ bacteria to grow. After this, the proC+ transductants were plated on selective media to reveal their genotypes at the other three pro loci. The following results were obtained:
Q.Why are there no proC− genotypes among the transductants?
Chapter 14 Solutions
Genetics: From Genes to Genomes
Ch. 14 - Choose the phrase from the right column that best...Ch. 14 - The unicellular, rod-shaped bacterium E. coli is 2...Ch. 14 - Now that the sequence of the entire E. coli K12...Ch. 14 - Bacterial genomes such as that of E. coli...Ch. 14 - List at least three features of eukaryotic genomes...Ch. 14 - Describe a mechanism by which a gene could move...Ch. 14 - High salt concentrations tend to cause protein...Ch. 14 - Recently, scientists tested the possibility that...Ch. 14 - A recent metagenomic study analyzed the...Ch. 14 - Linezolid is a new type of antibiotic that...
Ch. 14 - A liquid culture of E. coli at a concentration of...Ch. 14 - Pick out the medium i, ii, iii, or iv onto which...Ch. 14 - This problem concerns Fig. 14.14, which...Ch. 14 - In two isolates one is resistant to ampicillin,...Ch. 14 - E. coli cells usually have only one copy of the F...Ch. 14 - In E. coli, the genes purC and pyrB are located...Ch. 14 - DNA sequencing of the entire H. influenzae genome...Ch. 14 - Genes encoding toxins are often located on...Ch. 14 - a. You want to perform an interrupted-mating...Ch. 14 - In Problem 19, do you think that most of the...Ch. 14 - One issue with interrupted-mating experiments such...Ch. 14 - Prob. 22PCh. 14 - Starting with an F- strain that was prototrophic...Ch. 14 - You can carry out matings between an Hfr and F...Ch. 14 - Genome sequences show that some pathogenic...Ch. 14 - Generalized and specialized transduction both...Ch. 14 - This problem highlights some useful variations of...Ch. 14 - A researcher has a Trp auxotrophic strain of E....Ch. 14 - Streptococcus parasanguis is a bacterial species...Ch. 14 - The sequence at one end of one strand of the...Ch. 14 - Scientists who study amino acid biosynthesis...Ch. 14 - Suppose that you could obtain radioactively...Ch. 14 - Prob. 34PCh. 14 - Some scientists are trying to engineer...
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