1. If penicillin is added to a culture of bacterial cells in a liquid minimal me

Question

1. If penicillin is added to a culture of bacterial cells in a liquid minimal medium, which of the following will occur? • biochemical mutants survive because they are unable to divide in minimal medium • biochemical mutants die because they cannot divide without supplementation • wildtype cells survive because they are able to divide in the minimal medium • a few random cells may survive, but penicillin is highly lethal to all bacteria

2. In experiments in which they replica plated colonies from one non-selective plate to three different selective plates, the Lederburgs observed that most of the resistant colonies on the selective plates were in the same locations on all three plates, but a few were not in the same location. How did the Lederburgs explain the location of the colonies in the same place? • resistance to the selective agent was present in some colonies on the non-selective plate • resistance mutations occurred after the colonies were placed on the selective plates • variations in the surface of the agar could lead to colonies in the same places • physiological responses to the selective agent would account for this result

3. A bulk culture of bacteria is treated with penicillin. The survivors of this treatment should all be _____, which will be unable to grow on _____ medium. • wildtype - minimal • mutant - minimal • mutant - supplemented • there will be no survivors from a penicillin treatment

4. That mutation is a random process means that • all mutations are equally likely to occur • environmental agents have no effect on mutation rates • any gene may mutate at any time • beneficial mutations will be about as common as harmful ones

5. Which of the following methods would be best for isolating a bacterial mutant lacking the ability to synthesize the amino acid leucine? • replica plate on minimal and leucine supplemented medium, then penicillin enrich • penicillin enrich, then replica plate on minimal and leucine supplemented medium • penicillin enrich, then plate on minimal medium • any of these would work

6. 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

7. Which of the following strains represent a donor/recipient combination? • Hfr/F+ • F-/Hfr • F+/Hfr • Hfr/F-

Explanation / Answer

1. biochemical mutants survive because they are unable to divide in minimal medium

2. resistance to the selective agent was present in some colonies on the non-selective plate •

3. wildtype - minimal

4. beneficial mutations will be about as common as harmful ones

5. penicillin enrich, then replica plate on minimal and leucine supplemented medium

6. minimal only

7. Hfr/F+

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.