Which of the following statements about Hfr strains of E. coli is FALSE? Group of answer choices Hfr stands for "high frequency recombination" In Hfr strains, the F factor is integrated into the main bacterial chromosome The location and order of genes along the chromosome can be mapped using the time of transfer of different marker genes. Genetic exchange between Hfr and F− strains is studied using the interrupted mating technique In Hfr strains, the F factor is integrated into a plasmid

Which of the following statements about Hfr strains of E. coli is FALSE? Group of answer choices Hfr stands for "high frequency recombination" In Hfr strains, the F factor is integrated into the main bacterial chromosome The location and order of genes along the chromosome can be mapped using the time of transfer of different marker genes. Genetic exchange between Hfr and F− strains is studied using the interrupted mating technique In Hfr strains, the F factor is integrated into a plasmid

Biology: The Dynamic Science (MindTap Course List)

4th Edition

ISBN:9781305389892

Author:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Publisher:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Chapter17: Bacterial And Viral Genetics

Section: Chapter Questions

Problem 1ITD

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Which of the following statements about conjugation is false? After a F- cell has conjugated with an F+ cell, both cells would be F+. Both Hfr and F+ bacteria have the ability to produce a sex pilus. In F+ × F- conjugation, none of the bacterial chromosome is transferred; only the F factor is. A Hfr strain usually transfers the entire bacterial chromosome to the recipient cell. F' × F- conjugation can produce a partially diploid bacterial cell.
E. coli cells are simultaneously infected with two strains of phage λ. One strain has a mutant host range, is temperature sensitive, and produces clear plaques (genotype h st c); another strain carries the wildtype alleles (genotype h+ st+ c+). Progeny phages are collected from the lysed cells and are plated on bacteria. The following numbers of different progeny phages are obtained: Progeny phage genotype Number of plaques h+ c+ st+ 321 h c st 338 h+ c st 26 h c+ st+ 30 h+ c st+ 106 h c+ st 110 h+ c+ st 5 h c st+ 6 a. Determine the order of the three genes on the phage chromosome. b. Determine the map distances between the genes. c. Determine the coefficient of coincidence and the interference
A general transduction experiment was conducted to determine the gene order of trp, pyrF and qts loci on the bacterial chromosome. The Donor genotype is: trp+pyr+qts The Recipient genotype is: trp pyr qts+ The selected marker in this transduction experiment is trp+. Unselected Markers Number of colonies pyr+qts+ 22 pyr+qts 10 pyr qts+ 68 pyr qts 0 What is the full genotype of each of the 22 colonies for the 3 loci? What is the gene order of the 3 loci on the donor chromosome? How is co-transduction relevant to determining the answer to part b? Why is the name of the viral vector not given to help you answer this question?
The figure below shows a partial chromosome map of an E. coli Hfr strain. Each mark = 10 minutes between conjugation transfer time. If transfer of genes begins at “*” relative to the origin of transfer, what is one of the predicted results from this map? It would take less than 30 minutes to transfer all of the genes that are shown. gal and azi will rarely be transferred together. gal and ton will rarely be transferred together. Ten minutes after transfer of ton, lac will be transferred. This strain will produce very few gal recombinants.
Which of the following statement about conjugation is TRUE: During F+ to F- mating, the donor becomes F-. During the Hfr to F- transfer, the recipient becomes F+. The whole bacteria genome may get transferred during Hfr mating. During the Hfr to F- transfer, some recipients become recombinants in which transferred fragment recombines with homologous region in the genome.
By 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:Analyze data. Compare and contrast. Make a drawing.
A researcher is studying the rII locus of phage T4. FourrII− strains are obtained: A, B, C, and D. In the first experiment, E. coli strain K(λ) is coinfected with two rII− strains simultaneously and the results are recorded. Infection with A and B phage = lysis occurs Infection with A and C phage = lysis occurs Infection with B and C phage = no lysis occurs Infection with B and D phage = no lysis occurs Infection with C and D phage = no lysis occurs In a second experiment, coinfections are performed first in E. coli strain B, then the progeny phage are used to infect E. coli strain K(λ). Progeny of A and B phage = plaques form Progeny of B and C phage = plaques form Progeny of C and D phage = plaques form Progeny of B and D phage = no plaques from Which conclusions are consistent with these data? Why? A) Strains A and B carry mutations in the same gene. B) Strains B and D both carry the same mutation. C) Strains B, C, and D carry mutations in the same gene. D)…
Crosses are carried out between a bacterial F- strain and three different Hfr strains. In these strains, it takes 60 minutes for an Hfr strain to transfer the entire chromosome. Below are the data generated from interrupted mating experiments. Time of transfer of different genes (in minutes) is given for each strain. Appearance of genes in F- cells Hfr1: Genes b+ d+ c+ f+ g+ Time 3 5 16 27 59 Hfr2: Genes e+ f+ c+ d+ b+ Time 6 24 35 46 48 Hfr3 Genes d+ c+ f+ e+ g+ Time 4 15 26 44 58 Based on these data, you could conclude that Group of answer choices b is between g and d and is 4 minutes from g e is between f and g and is 25 minutes from g g is between e and b and is 24 minutes from e none of these is correct d is between b and c and is 10 minutes from b
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?
A group of genetics students mix two auxotrophic strains of bacteria: one is leu+ trp+ his− met− and the other is leu− trp− his+ met+. After mixing the two strains, they plate the bacteria on minimal medium and observe a few prototrophic colonies (leu+ trp+ his+ met+). They assume that some gene transfer has taken place between the two strains. How can they determine whether the transfer of genes is due to conjugation, transduction, or transformation?
By 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 oftheir experimental results is shown in the following table: A. E xplain how these results are consistent with the idea that thebacterial chromosome is circular.B. Draw a map of the bacterial chromosome that shows the orderof genes and the locations of the origins of transfer among thesedifferent Hfr strains.
The Kishony performed a simple but elegant experiment using a “mega-plate.” Which of the following is a fair conclusion that can be drawn from this study? The majority of antibiotic resistance occurs via horizontal gene transfer (HGT) between Actinobacteria Sensitive bacteria may acquire resistance to high concentrations of the antibiotic through many mutations Bacteria will gradually lose resistance to an antibiotic if you plate them on a large enough plate Bacteria will migrate via chemotaxis away from recombinant phage used in phage therapy