Bioc 384 Exam 3 All Updated Actual Questions And Correct Answers

BIOC 384 EXAM 3 ALL UPDATED ACTUAL QUESTIONS
AND CORRECT ANSWERS

Question:
1. Module 7

Answer:
Start

Question:
2. Acetylcholinesterase is an important enzyme in the
nervous system. Acetylcholinesterase activity is blocked
by the nerve agent sarin gas, which forms a covalent
bond with a Ser in the active site of the enzyme. Sarin gas
is a(n)
irreversible inhibitor.
competitive inhibitor.
reversible inhibitor.
allosteric effector.

Answer:
irreversible inhibitor.
"forms a covalent bond with a Ser"

Question:
3. An inhibitor that binds only to the ES complex and not
free enzyme is known as a(n) ___________ inhibitor.
competitive
uncompetitive
irreversible
mixed

Answer:
uncompetitive

,Question:
4. An enzyme undergoes a mutation that causes it to lose
the ability to be regulated via phosphorylation. Which of
the following mutations may lead to this loss of
regulation? Assume that the overall structure is not
altered by the mutation.
Tyr --> Phe
Thr --> Ser
Ser --> Tyr
Ser --> Thr

Answer:
Tyr --> Phe

Question:
5. Put the following steps in the correct order describing
inhibition of glutamine synthetase by a metabolite
allosteric effector.
A. Adenylation of glutamine synthetase.
B. Glutamine binding to uridylyltransferase
C. Deuridylation of glutamine synthetase
adenylyltransferase
B, C, A
B, A, C
C, B, A
A, B, C

Answer:
B, C, A
B. Glutamine binding to uridylyltransferase
C. Deuridylation of glutamine synthetase adenylyltransferase
A. Adenylation of glutamine synthetase.

,Question:
6. Put the following signal transduction pathway steps in the
correct order:
upstream signaling protein
second messenger
receptor protein
first messenger
target proteins
downstream signaling protein
D, C, A, B, F, E
C, D, A, B, F, E
D, C, B, A, F, E
D, E, C, A, B, F

Answer:
D, C, A, B, F, E
first messenger
receptor protein
upstream signaling protein
second messenger
downstream signaling protein
target proteins

Question:
7. Muscle relaxation in response to neuronal stimulation and
nitric oxide signaling would be reduced if a(n)
______________was present.
inhibitor of protein kinase A
stimulator of cGMP phosphodiesterase
stimulator of guanylate cyclase
inhibitor of acetylcholine esterase

Answer:
stimulator of cGMP phosphodiesterase

Question:
8. The GS-alpha subunit of trimeric G proteins can function
to
inhibit phosphodiesterase.
regulate ion channels.
activate adenylate cyclase.
inhibit phospholipase A.

Answer:
activate adenylate cyclase.

, Question:
9. When protein kinase A (PKA) is inactive, which of the
following is true?
the regulatory subunit has cyclic GMP bound in place of
cyclic AMP
ATP is bound to the regulatory subunit to inhibit subunit
dissociation
the intrinsic pseudo substrate peptide is bound to the
active site
cAMP is bound to the catalytic site to inhibit the
regulatory subunit

Answer:
the intrinsic pseudo substrate peptide is bound to the active site

Question:
10. The β2-adrenergic receptor is best characterized as
which of the following?
:mostly α helices
none of the above
mostly β sheets
mostly β turns

Answer:
:mostly α helices

Question:
11. Which binding site most likely represents the area of
greatest structural change in response to ligand binding?
SOS binding
DNA binding
heterotrimeric G protein binding
cAMP binding

Answer:
heterotrimeric G protein binding