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MCB 3020 General Microbiology
Fall, 2011
EXAM 2
Name:
PantherID:
Directions: Write and Bubble-In your Name and Panther ID on the Scantron Answer Sheet AND Write
them on the Exam (above). Please answer each multiple choice question with the BEST POSSIBLE answer
on the Scantron Answer Sheet ONLY.
Multiple Choice Questions (2 pts each)
1. The RNA genome of the potato spindle tuber viroid requires which type of host polymerase to replicate
itself?
a. DNA-dependent DNA polymerase. b. DNA-dependent RNA polymerase.
c. RNA-dependent DNA polymerase. d. RNA-dependent RNA polymerase. e. reverse transcriptase.
2.
gained notoriety when they were implicated in brain infections, such as the popularly
known mad cow disease.
a. Viroids. b. Viruses. c. Prions. d. Bacteria. e. Virons.
3. In bacteriophage T4, the DNA denome is contained in the head, and binding to the host is facilitated by:
a. capsid. b. neck. c. tail fibers. d. envelope. e. tegument.
4. The genome of
a. positive sense.
5.
a.
c.
e.
ssRNA viruses can serve directly as mRNA.
b. negative sense. c. all. d. double stranded. e. prion.
Which of the following is NOT part of the life cycle of a lytic phage?
Phage DNA is injected into the bacteria. b. Phage DNA integrates into the host chromosome.
Many copies of phage DNA are made. d. Phage DNA is transcirbed and translated to capsomeres.
All of the above are steps of the life cycle of a lytic phage.
6. Which of the following is false concerning HIV?
a. It causes AIDS. b. It makes a DNA copy of its RNA genome. c. Reverse transcriptase is translated from
an early gene. d. the virion contains two copies of the HIV genome. e. Viral RNA is positive stranded.
7. Conjugation takes approximately how many minutes to move the entire Escherichia coli genome from one
cell to another?
a. 10.
b. 20. c. 50. d. 100. e. 200.
8.
are bicyclic bases and
a. Prymidines; purines. b. Adenines; guanines.
e. Purines; pyrimidines.
are monocyclic bases.
c. Thymines; uracils. d. Thymines; cytosines.
9. The nucleoid of E. coli when gently released appears as 30 to 100 tightly wound loops, each defined by
anchoring proteins called:
a. histones. b. histone-like proteins. c. supercoils. d. gyrase.. e. topoisomerase.
10. The DNA of phage T4 recplicates by the
a. semiconservative. b. conservative. c. bidirectional.
11.
a. Histones.
method.
d. operon.
e. rolling circle.
naturally function to cut the DNA of invading plasmids and phages at specific points.
b. Gyrases. c. Ligases. d. Polymerases. e. Restriction enzymes.
12. The housekeeping sigma factor of E. coli is:
a. sigma-28. b. sigma-38. c. sigma-70. d. sigma- 54.
e. sigma-90.
13. What do codons and anticodons have in common?
a. They are part of t-RNA. b. They are sequences on DNA being 3 nucleotides long.
c. They are identical RNA sequences. d. They are complimentary RNA sequences.
e. none of the above.
14. The signifcance of the Shine-Dalgarno sequence is that it is the site where:
a. RNA polymerase binds to DNA. b. ribosomes bind to begin translation.
c. DNA polymerase binds to begin replication. d. t-RNA binds to begin m-RNA translation.
e. DNA polymerase binds to begin synthesis of Okazaki fragments on the lagging strand.
15. The energy source for translation is:
a. proton motive. force. b. ATP. c. phosphoenol-pyruvate hydrolysis.
d. GTP. e. none is required.
16. The general protein secretion complex known as SecYEG is found in the:
a. nucleus. b. inner membrane. c. cell wall. d. periplasmic space. e. outer membrane.
17.
a. Ubiquitination.
controls protein turnover by closely regulating the degradation of specific proteins.
b. Half-life. c. Amino acid sequence. d. Tertiary structure. e. Protease.
18. Interrupted mating involves breaking the
a. transformation. b. transduction. c. conjugation.
19. A
a. Colored.
bridges using a blender.
d. transposition. e. recombination.
colony is the result of a high mutation rate.
b. Wrinkled. c. Large. d. Sectored. e. Convex.
20. In some, but not all, instances,
molecules bind RNA transcripts and help or hinder degradation.
a. sRNA. b. rRNA. c. tRNA. d. mRNA. e. tmRNA.
21. Transcription attenuation is a common regulatory strategy used to control many operons that code for:
a. amino acid degradation. b. carbohydrate degradation. c. amino acid synthesis.
d. carbohydrate synthesis. e. none of these.
22. The stringent response relies on the production of:
a. pG. b. ppG. c. pppG. d. ppGpp. e. pGp.
23. Quorum sensing gene systems require the accumulation of secreted small molecules called a/an:
a. autoinducer. b. activator. c. inducer.
d. repressor. e. corepressor.
24. A bacterium capable of producing methane and water from carbon dioxide and hydrogen performs a type
of metabolism called
and given its source of electrons, it is a/an
.
a. methanogenesis; lithotroph. b. respiration; heterotroph.
c. fermentation; organotroph.
d. carbon fixation; phototroph. e. none of the above.
25. Glycolytic reactions with a near-zero ∆Go’ can particpate in the over all pathway of gluconeogenesis
because they are:
a. reversible. b. irreversible. c. have low energy of activation. d. contradict the thermodynamic laws.
e. none of the above.
26. Fermentation can be defined as a metabolism:
a. without an electron transport system. b. without a terminal electron acceptor.
c. without further production of ATP after a few substrate-level phosphorylations.
d. in the absence of oxygen. e. all of the above.
27. What molecule serves as the major entry for lipid derived fatty acids from the TCA cycle.
a. acetyl phosphate. b. malonlyl-S-CoA. c. acetyl-S-CoA. d. all of these. e. none of these.
28. Which of the following is NOT an end product of fermentation?
a. carbon dioxide. b. acetone. c. pyruvate. d. butanol. e. none of the above.
29. The dye
turns
broths used in diagnostic tests..
in the presence of acid products and is part of fermentation
a. phenol red; yellow.
e. phenol red; red.
b. aniline blue; green.
c. ethidium bromide; pink.
d. malachite green; blue.
30. The greatest amount of NADH is produced during which stage of aerobic respiration?
a. glycolysis. b. puryvate conversion to acetyl-S-CoA. c. TCA cycle. d. glyoxylate bypass.
e. oxidative phosphorylation.
31. In the electron transport system, each cytochrome receives electrons from a stronger
and
transfers them to a stronger
.
a. nitrogen compound series; sulfur compound series. b. oxidant; reductant. c. inorganic donor; oranic
donor. d. reductant; oxidant. e. none of the above.
32. Which of the following is NOT a terminal electron acceptor in anaerobic respiration.
a. ntirate. b. nitrite. c. sulfate. d. carbon dioxide. e. hydrogen sulfide.
33. The chomophore of bacteriorhodopsin is?
a. tochopherol. b. chlorophyl. c. folic acid.
d. retinal.
e. β-carotene.
34. The chemiosmotic model does NOT explain synthesis of ATP in:
a. the chloroplast thylakoid membrane. b. the inner mitochondrial membrane.
c. substrate level phosphorylations. d. the purple bacterial thylakoids. e. inner memrane of Gram-negative
bacteria.
35. The proton motive force drives the following processes in bacteria:
a. ATP biosynthesis from ADP and Pi. b. flagella rotation. c. nutrient uptake. d. answers a and c.
e. answers a and b.
Written Answer Questions.
1. A culture containing 3 x 106 E. coli /mL was infected with phage T-4 at a multiplicity of infection of 1.0.
After 25 minutes, the lytic cycle of T-4 was complete with a burst size of 123. What is the resulting virus titer in
this culture? (10 points).
2. An ORF of 1400 base pairs in length (not including the promoter and terminator complexes) could encode
a protein of: a) what length (in amino acids) and; b) molecular weight (assume 110 daltons as the weight of the
average amino acid in proteins)? (10 points)
3. Suppose an E. coli culture growing aerobically on acetate (1 µM) is pulsed labeled with 14C-acetate (in sub
µM amounts) for 10 seconds and then chased with 10 mM 12C-acetate. Using the graph below what you would
expect to happen to the radioactivity observed in TCA intermediates. (10 points)
14
C in TCA Intermediates
Time, minutes ==>