Micro 320, Exam 1. Name______________
Place your name at the top. Your exam should have 20 questions and 6 pages. If not, please let me know. Each question is worth 5 points.
1. From the graph below, what is the generation time (g). logN – logN o
/t-t o
= µ/2.303 calculate µ (specific growth rate constant).
Generation time (g) = 0.693/μ
N number of cells
N o
= number of cells at the starting time. t = time t o
= the starting time
2. If you wanted to replicate DNA in vitro (in a test tube) without helicase (all the other enzymes are present), what would you need to do?
3. What distinguishes leading and lagging strand replication?
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4. Your goal is to engineer E. coli to express 10 specific genes (used for production of a new drug) when it enters stationary phase but you do not want these genes expressed at other times. How might a sigma factor be used to accomplish this, explain.
5. What does it mean to say that transcription and translation are coupled in bacteria?
6. Draw an mRNA and show the five key parts of the mRNA that are needed for translation.
7. Explain the function of EF-tu/Ef-ts in translation
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8. Considering how they function, do you think that DnaKJ and GroEL/GroES should be classified in the same group of chaperones, explain.
9. How do cells protect normal, properly folded, proteins from the Lon and Clp proteases?
10. How would a mutation that inactivates the Sec system affect proteins that are
(i) destined for the periplasm
(ii) destined for insertion in the inner membrane
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11. Explain how type III secretion systems function and their evolutionary relationships?
12. What is the role of proteases in the regulation of gene expression?
13. Consider homologous recombination between the linear and circular DNA molecules shown at the right.
(i) draw the results of a single cross over
(ii) draw the result of a double cross-over
(iii) show the effects of branch migration on the single crossover.
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14. What is the role of the RecA protein in recombination?
15. Which two of the three systems listed below are best for the repair of thymine dimers and why? methyl-directed mismatch repair photoreactivation repair nucleotide excision repair
16. Explain how the SOS response is induced?
17. Suggest how a restriction modification system could be converted to a toxin antitoxin module used for plasmid maintenance?
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18. How is quorum sensing involved in competence in Streptococcus?
19. What determines host specificity of a particular bacteriophage?
20. How does the CRISPR system in recognize an invading virus?
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