8. A small circular chromosome within a bacterial host would be called • virus •

Question

8. A small circular chromosome within a bacterial host would be called • virus • phage • mutation • plasmid

9. In experiments to map bacterial genes, which of genetic combinations listed below correctly characterizes the donor and recipient strains? • donor: strepS, wildtype genes; recipient: strepR, mutant genes • donor: strepR, wildtype genes; recipient: strepS, mutant genes • donor: strepS,mutant genes; recipient: strepR, wildtype genes • donor: strepR, mutant genes; recipient: strepR, wildtype genes

10. In an experiment to determine whether DNA or protein is the hereditary material, one culture of phage (A) is grown on a medium with radioactive sulfur and another (B) is grown on a medium with radioactive phosphorus. These are then used to infect different bacterial cultures. The rationale for growing the phage on different cultures is that • DNA contains sulfur, protein contains phosphorus • phage grow at different rates when grown on radioactive media • in strain B the DNA will be radioactive, in strain A the protein will be • only strain B will be able to infect bacteria

11. Given what you know about the identity of the hereditary material, which of the following will be observed as an outcome of the above experiment? • radioactivity will be found inside all infected bacterial cultures • radioactivity will not enter any of the infected bacteria • radioactivity will be found inside only the bacteria infected with phage A • radioactivity will be found inside only the bacteria infected with phage B

12. Bacterial cells divide by a process called binary fission, as opposed to the mitotic process that occurs in eukaryotic cells. Why is bacterial cell division not called mitosis? • bacterial cells do not contain a nucleus • bacterial chromosomes do not have a centromere • spindles do not form in bacterial cells • all of these

13. If mutants deficient in the ability to synthesize histidine are desired, which of the following combinations of plates will allow those mutants to be isolated? • minimal only • histidine supplement only • minimal and histidine supplement • either b or c would work

14. Conjugating strains of bacteria are separated and the wildtype genes present in the recipient assessed. It is found that 80% of the exconjugants have received gene a+, and about 60% have received gene b+. Which of the following conclusions is correct? • gene a is transferred first, then gene b • gene b is transferred first, then gene a • both genes are transferred about the same time • valid conclusions about gene order cannot be inferred from this information

Explanation / Answer

ANSWERS

8 option D Plasmid is correct

9. Option D, Donor: Strep R, mutant gene; recipient: Strep R, wild type gene

10. Option D, only the stain B will be able to infect bacteria is correct

11. option D, radioactivity will be found inside only the bacteria infected with phage B

12. Option D, all the above options are correct

13. Option C, Minimal and histidine supplement

14. Option D, valid conclusion about gene order cannot be inferred from this information

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