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 19P
| a. | You want to perform an interrupted-mating mapping with an E. coli Hfr strain that is Pyr, Met, Xyl Tyr, Arg, His, Mal, and Strs. Describe an appropriate bacterial strain to be used as the other partner in this mating. |
| b. | In an Hfr × F cross, the pyrE gene enters the recipient in 5 minutes, but at this time point there are no exconjugants that are Met, Xyl, Tyr, Arg, His, or Mal . The mating is now allowed to proceed for 30 minutes and Pyr exconjugants are selected. Of the Pyr cells, 32% are Met, 94% are Xyl, 7% are Tyr, 59% are Arg, 0% are His, and 71% are Mal . What can you conclude about the order of the genes? |
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. a. You want to perform an interrupted-mating mappingwith an E. coli Hfr strain that is Pyr+, Met+, Xyl+,Tyr+, Arg+, His+, Mal+, and Strs. Describe anappropriate bacterial strain to be used as theother partner in this mating.b. In an Hfr × F− cross, the pyrE gene enters therecipient in 5 minutes, but at this time point thereare no exconjugants that are Met+, Xyl+, Tyr+,Arg+, His+, or Mal+. The mating is now allowed toproceed for 30 minutes and Pyr+ exconjugants areselected. Of the Pyr+ cells, 32% are Met+, 94% areXyl+, 7% are Tyr+, 59% are Arg+, 0% are His+, and71% are Mal+. What can you conclude about theorder of the genes?
In 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 gene
a) Sam wants to alter his interrupted mating experiment by placing a filter in between the donor and the recipient cells in order to separate the two. Is Sam’s suggestion for this modification to the procedure utilized in interrupted mating experiments valid? Explain.
b) Much to the dismay of the researcher with whom Sam is working, Sam is not only forgetful, but he is also lazy! Rather than devoting the necessary hours to conducting his assigned interrupted mating experiments, Sam has decided that his time would be better spent modifying the F plasmid so that the experiments wouldn’t require quite so much time. The diagram below shows a map of the E. coli F plasmid, similar to that shown in lecture. Sam is determined to “get rid of some of the excess DNA” present in the plasmid. Please keep in mind that the PI in the lab in which Sam works utilizes these F plasmids for interrupted mating experiments between Hfr and F- cells as well as for interrupted mating experiments involving F+…
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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- Four Hfr strains are derived from an F+ strain of E. Coli to serve as donors for an interrupted-mating experiment. Use the time-table and partial map of the F+ strain (shown below) to determine the genes’ respective positions. Keep in mind that the map distances are NOT proportional, only the FIRST 5 markers are indicated per strain, and the entry times, recorded in minutes, are in parentheses. Transferred genes represent wild-type alleles. Based on the data, which gene can be located at position 5 on the map?arrow_forwardAn Hfr strain is used to map three genes in an interrupted mating experiment. The cross is Hfr/a+b+c+ rif x F-a-b-c- rifr (note that rifr is resistance to the antibiotic rifampicin). The a+ gene is required for the biosynthesis of nutrient A, the b+ gene for nutrient B, and the c+ gene for nutrient C. The cross is initiated at time=0. At various times, the mating mixture is plated out on three different types of medium. Each plate contains minimal medium (MM) plus rifampicin, plus specific supplements that are listed in the table below. The results for each time interval are shown as the number of colonies growing on each plate.An Hfr strain is used to map three genes in an interrupted mating experiment. The cross is Hfr/a+b+c+ rif x F-a-b-c- rifr (note that rifr is resistance to the antibiotic rifampicin). The a+ gene is required for the biosynthesis of nutrient A, the b+ gene for nutrient B, and the c+ gene for nutrient C. The cross is initiated at time=0. At various times, the…arrow_forwardBy 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?arrow_forward
- In five Hfr strains, each of which was used to build a time-of-transfer map, the genes entered the recipient cells as follows: Strain 1: S L A C T F Strain 2: N P F T C A Strain 3: T F P N U Y Strain 4: S H Y U N P Strain 5: U N P F T C Which of the following represents a correct gene map of these results? N P F T S L A C H U Y S L A C T F P N H Y U C T F P N U Y H S L A T C A L S P N U Y H F U N P C A L S F T H Yarrow_forwardBy 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 following table:What information do you know based on the question and your understanding of the topic?arrow_forwardT. 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?arrow_forward
- 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.arrow_forwardT. 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?arrow_forwardAustin 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…arrow_forward
- With the technique of interrupted mating four Hfr strains were tested for the sequence in which they transmitted a number of different genes to an F strain. Each Hfr strain was found to transmit its genes is a unique sequence, as shown in the accompanying table. What is the gene sequence in the original strain from which these Hfr strains were derived?arrow_forwardAn Hfr strain that is leuA+ and thiL+ was mixed with a strain thatis leuA− and thiL−. In the data points shown in the following graph,the conjugation was interrupted at different time points, and thepercentage of recombinants for each gene was determined bystreaking on a medium that lacked either leucine or thiamine.What is the map distance (in minutes) between these two genes?arrow_forwardAustin 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.arrow_forward
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