Practice Exam 2

Question 1

Which processes BEST define the major pathways for energy production in the chemoorganotroph Escherichia coli?

a) Anabolism and catabolism
b) Glycolysis and NADH synthesis
c) Respiration and fermentation
d) Photosynthesis and Calvin cycle
e) Substrate-level phosphorylation and glucose synthesis

Answer 1

c) Respiration and fermentation

Question 2

Which of the following is FALSE for catabolic and anabolic pathways?
a) In these pathways, the product of one reaction often serves as a substrate for the next
reaction
b) These pathways are reversible
c) Amphibolic pathways can be used catabolically or anabolically
d) Anabolic pathways generally do not require energy
e) They degrade and build macromolecules, respectively

Answer 2

d) Anabolic pathways generally do not require energy

Question 3

Which of the following concerning respiration in E. coli is TRUE?
a) Electron transfer results in the generation of proton motive force
b) The generated proton motive force is used for substrate level phosphorylation
c) The electron donor is typically NAD+ or FAD+
d) Protons are transferred to an exogenous proton acceptor
e) The membrane potential is generated at the cell’s outer membrane

Answer 3

a) Electron transfer results in the generation of proton motive force

Question 4

Which is regarded as the most general chemical currency for energy in cells?
a) Proton motive force
b) Glucose
c) NADH
d) ATP
e) ADP + Pi

Answer 4

d) ATP

Question 5

Which of the following is not produced by fermentation?
a) Coffee
b) Milk
c) Yogurt
d) Soy sauce
e) Cheese

Answer 5

b) Milk

Question 6

Which of the following statements concerning metabolic fueling is FALSE?
a) Chemoorganoheterotrophs use organic carbon compounds as both energy and carbon sources
b) Photosynthesis provides energy but does not reduce CO2
c) Oxidative phosphorylation does not require oxygen
d) Anaerobic and aerobic respiration in principle can yield similar amounts of energy e) The general strategy is to break-down macromolecules for fuel as needed

Answer 6

d) Anaerobic and aerobic respiration in principle can yield similar amounts of energy

Question 7

Which of the following statements is FALSE concerning the TCA cycle?
a) The TCA cycle can be run in the reverse direction for direct biosynthesis
b) The TCA cycle produces NAD+ and FAD+
c) A major function of running the TCA cycle in the forward direction is for respiration
d) The TCA cycle occurs in the cytoplasm of bacteria
e) Other names for the TCA cycle are the citric acid cycle and the Krebs cycle

Answer 7

b) The TCA cycle produces NAD+ and FAD+

Question 8

Using the following values for E0, which of the electron acceptors in principle should generate the most ATP during aerobic respiration [consider NADP+ and NAD+ as interchangeable]:
a) Fe3+
b) O2
c) NO2-
d) NAD+
e) NO3-

Answer 8

b) O2

Question 9

Which of the following statements concerning oxidative phosphorylation is FALSE?
a) It requires O2 as the terminal electron acceptor
b) Endogenous electron acceptors are not used as the terminal electron acceptors
c) NADH and FADH2 are important substrates used in this process
d) Proton motive force is used to synthesize ATP using the F1FO ATP synthase
e) It needs a functional electron transport chain

Answer 9

a) It requires O2 as the terminal electron acceptor

Question 10

The chemical compound oligomycin, when added to cells, binds to the FO subunit of F1FO ATP synthase and blocks proton flow through the channel. Which of the following would be expected to be a consequence of adding oligomycin to cells:
a) Decrease fermentation pathway use
b) Increase ATP production by the ATP synthase
c) Increase cell growth
d) Increase respiratory capacity
e) Decrease the efficiency of oxidative phosphorylation

Answer 10

e) Decrease the efficiency of oxidative phosphorylation

Question 11

Which of the following statements concerning fermentation is TRUE?
a) Fermentation ultimately provides NAD+
b) Fermentation requires oxygen
c) Glucose is an important direct end-product of fermentation
d) The F1FO ATP synthase is important for fermentation
e) Proton motive force is used in fermentation

Answer 11

a) Fermentation ultimately provides NAD+

Question 12

Which of the following statements concerning peptidoglycan synthesis is TRUE?
a) Animal cells also synthesize peptidoglycan
b) Bactoprenol leaves the membrane each time it ferries molecules across the membrane c) Peptidoglycan contains fatty acids
d) The pentapeptide is added to NAM in the cytoplasm.
e) Uridine diphosphate (UDP) derivatives of NAG and NAM combine in the periplasm

Answer 12

d) The pentapeptide is added to NAM in the cytoplasm.

Question 13

Which of the following is not a direct step in bacterial cell wall biosynthesis?
a) Polymerization of individual peptidoglycan chains
b) Cross-linking of adjacent peptidoglycan chains
c) Synthesis of lipopolysaccharide
d) Synthesis of Lipid I
e) Synthesis of UDP-NAG

Answer 13

c) Synthesis of lipopolysaccharide

Question 14

The finished product of peptidoglycan synthesis is:
a) The periplasmic space
b) The cell wall
c) The cell matrix
d) The cell envelope e) The capsule

Answer 14

b) The cell wall

Question 15

Which of the following components is MOST directly responsible for the physical mechanism of E. coli chromosomal DNA replication?
a) Synthesis by the ribosome
b) RNA-dependent RNA polymerase
c) DNA-dependent RNA polymerase
d) RNA-dependent DNA polymerase
e) DNA-dependent DNA polymerase

Answer 15

e) DNA-dependent DNA polymerase

Question 16

Which of the following statements concerning bacterial chromosomal DNA replication is FALSE?
a) Chromosomal DNA replication is bi-directional and requires a defined origin
b) DNA synthesis occurs by a mechanism that is called semi-conservative
c) No special machinery is needed to complete the process of separating the duplicated
chromosomes at the completion of chromosomal DNA replication
d) DNA or RNA can serve as primers for DNA synthesis
e) It requires the replisome

Answer 16

c) No special machinery is needed to complete the process of separating the duplicated
chromosomes at the completion of chromosomal DNA replication

Question 17

Which of the following statements about DNA replication is TRUE based on the model presented in class?
a) The leading strand is replicated discontinuously; the lagging strand is replicated continuously
b) Both the leading and lagging strands are replicated discontinuously
c) The leading strand is replicated continuously; the lagging strand is replicated
discontinuously
d) The leading and lagging strands are each replicated both continuously and discontinuously e) Both the leading and lagging strands are replicated continuously

Answer 17

c) The leading strand is replicated continuously; the lagging strand is replicated
discontinuously

Question 18

Which of the following statements concerning E. coli RNA polymerase function is TRUE?
a) Fully functional enzyme requires in addition only a proper DNA template and NTPs (ATP,
GTP, CTP and UTP) for normal function
b) The holoenzyme is composed of the catalytic subunits only
c) E. coli RNA polymerase requires a primer
d) RNA polymerase binds to DNA at the promoter to initiate translation
e) Three distinct types of RNA polymerase are used: one for rRNA, one for tRNA and one
for mRNA

Answer 18

a) Fully functional enzyme requires in addition only a proper DNA template and NTPs (ATP,
GTP, CTP and UTP) for normal function

Question 19

Which of the following statements concerning bacterial transcription is TRUE?
a) Transcription initiates at start codons
b) The promoter sequence is included in the transcript
c) Sigma factor is important for choosing the transcription initiation site
d) The transcript is produced by addition of nucleotides in the 3’ to 5’ direction
e) Rho factor is important for the transcription apparatus to remain associated with the DNA
it is transcribing

Answer 19

c) Sigma factor is important for choosing the transcription initiation site

Question 20

Which of the following components is needed for the function of Rho-independent prokaryotic transcription terminators discussed in class?
a) A GC-rich stem structure
b) A stop codon
c) A sigma factor binding site
d) A GC-rich stem structure followed by a string of U nucleotides
e) A Rho factor binding site

Answer 20

d) A GC-rich stem structure followed by a string of U nucleotides

Question 21

Which of the following statements concerning bacterial translation is FALSE?
a) The peptidyl-transferase reaction occurs in the large ribosomal subunit
b) The large and the small ribosomal subunits are both needed for translation elongation
c) Codon-recognition occurs in the small ribosomal subunit
d) Aminoacylated tRNA must enter the ribosome at the ribosome E-site
e) Occurs in the same cellular compartment as transcription

Answer 21

d) Aminoacylated tRNA must enter the ribosome at the ribosome E-site

Question 22

Which of the following statements concerning Escherichia coli translation is TRUE?
a) Deacylated tRNA can be used to insert amino acids into polypeptides if the level of
aminoacylated tRNA gets too low
b) Sigma-subunit is directly important for initiating translation
c) Formyl-methionine (fMet) is used as the first amino acid to be put into new polypeptides
d) Translation terminates when special tRNAs are used to decode stop codons
e) Base-pairing between the large ribosomal subunit rRNA and the mRNA is important for
translation termination

Answer 22

c) Formyl-methionine (fMet) is used as the first amino acid to be put into new polypeptides

Question 23

What are these molecules as presented from left to right?
a) A,C,G,T,U
b) T,A,C,G,U
c) T,G,C,A,U
d) U,A,C,G,T
e) U,G,C,A,U

Answer 23

b) T,A,C,G,U

Question 24

Two antibiotics that interfere with bacterial peptidoglycan synthesis and the steps they affect are:
a) tetracycline – crosslinking peptidoglycan chains; bacitracin – membrane shuttling of peptidoglycan subunits
b) doxycycline – pentapeptide synthesis; ampicillin – crosslinking peptidoglycan chains c) vancomycin – peptidoglycan elongation; cycloserine – pentapeptide synthesis
d) rifampin – peptidoglycan elongation; cycloserine – peptidoglycan crosslinking
e) bacitracin – NAG synthesis; vancomycin – pentapeptide synthesis

Answer 24

c) vancomycin – peptidoglycan elongation; cycloserine – pentapeptide synthesis

Question 25

Based on the genetic code table, what are the FIRST THREE AMINO ACIDS encoded by the following DNA sequence, starting at the +1 nucleotide:
AUGCCUCAGAGGUAUUGA
a) Met His Gly
b) Cys Met Asp
c) Ala Trp Ile
d) Ile Gln Gly
e) None of the above

Answer 25

e) None of the above