BIOC 384 EXAM 3 100% ACCURATE
irreversible inhibitor - ANSWERAcetylcholinesterase 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)
uncompetitive - ANSWERAn inhibitor that binds only to the ES complex and not free
enzyme is known as a(n) __________ inhibitor.
reversible inhibition - ANSWERAn enzyme regulatory mechanism that involves the
noncovalent binding of small biomolecules or proteins to an enzyme subunit.
irreversible inhibition - ANSWERAn enzyme regulatory mechanism in which an
inhibitory molecule forms a covalent bond with catalytic groups in the enzyme active
site.
diisopropylfluorophosphate - ANSWERA highly reactive compound that serves as an
irreversible enzyme inhibitor by forming a covalent link with serine residues, blocking
protease and phospholipase enzymes.
competitive inhibitors - ANSWERA molecule that inhibits substrate binding at the active
site.
uncompetitive inhibitors - ANSWERA molecule that binds to enzyme-substrate
complexes and alters the active site conformation, thus rendering the enzyme less
catalytically active.
mixed inhibitors - ANSWERA molecule that binds to sites distinct from the enzyme
active site, but can bind to both the enzyme and the enzyme-substrate complex.
noncompetitive inhibition - ANSWERA special case of mixed inhibition in which a
molecule has equal affinity for both the free enzyme and the enzyme-substrate
complex.
feedback inhibition - ANSWERAn enzyme regulatory mechanism where the end product
of a pathway functions as an inhibitor of the first enzyme in the pathway.
kinase - ANSWERAn enzyme that catalyzes the transfer of a phosphoryl group, usually
from ATP to a substrate.
adenylylation - ANSWERA covalent modification of an enzyme by addition of AMP that
serves to regulate catalytic activity.
, uridylylation - ANSWERA process that regulates enzyme activity by controlling
adenylylating and deadenylylating activity.
zymogens - ANSWERAn inactive enzyme precursor that is activated by a proteolytic
cleavage reaction. (aka proenzymes)
Enzyme activity in the cell is regulated by both bioavailability and catalytic efficiency.
Regulating enzyme bioavailability can be a rather slow process, but in contrast,
reversibly regulating the catalytic efficiency of an enzyme can be rapid and is an
efficient means to control signal transduction and metabolic processes tightly. The three
primary mechanisms of reversible regulation in the cell are competitive inhibition,
allosteric regulation, and most forms of covalent modification. - ANSWERHow is the
catalytic activity of an enzyme reversibly regulated to facilitate on/off control?
Tyr to Phe - ANSWERAn 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
B, C, A - ANSWERPut 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
D, C, A, B, F, E - ANSWERConstruct a functional signal transduction pathway by
placing the following actors in thecorrect order:A. upstream signaling proteinB. second
messengerC. receptor proteinD. first messengerE. target proteinsF. downstream
signaling protein
stimulator of cGMP phosphodiesterase - ANSWERMuscle relaxation in response to
nitric oxide would be reduced if a(n) __________ was present
receptor protein - ANSWERA protein that stimulates a cellular response after protein
structural changes initiated by binding of a ligand.
target proteins - ANSWERAn intracellular protein that is modified as a result of an
upstream signaling pathway.
covalent protein modifications, protein conformational changes, altered rates of protein
expression - ANSWERthe effect of activating a receptor protein involves one or more of
these biochemical responses
cell signaling pathway - ANSWERA linked set of biochemical reactions that are initiated
by ligand-induced activation of a receptor protein and terminated by a measurable
cellular response.
irreversible inhibitor - ANSWERAcetylcholinesterase 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)
uncompetitive - ANSWERAn inhibitor that binds only to the ES complex and not free
enzyme is known as a(n) __________ inhibitor.
reversible inhibition - ANSWERAn enzyme regulatory mechanism that involves the
noncovalent binding of small biomolecules or proteins to an enzyme subunit.
irreversible inhibition - ANSWERAn enzyme regulatory mechanism in which an
inhibitory molecule forms a covalent bond with catalytic groups in the enzyme active
site.
diisopropylfluorophosphate - ANSWERA highly reactive compound that serves as an
irreversible enzyme inhibitor by forming a covalent link with serine residues, blocking
protease and phospholipase enzymes.
competitive inhibitors - ANSWERA molecule that inhibits substrate binding at the active
site.
uncompetitive inhibitors - ANSWERA molecule that binds to enzyme-substrate
complexes and alters the active site conformation, thus rendering the enzyme less
catalytically active.
mixed inhibitors - ANSWERA molecule that binds to sites distinct from the enzyme
active site, but can bind to both the enzyme and the enzyme-substrate complex.
noncompetitive inhibition - ANSWERA special case of mixed inhibition in which a
molecule has equal affinity for both the free enzyme and the enzyme-substrate
complex.
feedback inhibition - ANSWERAn enzyme regulatory mechanism where the end product
of a pathway functions as an inhibitor of the first enzyme in the pathway.
kinase - ANSWERAn enzyme that catalyzes the transfer of a phosphoryl group, usually
from ATP to a substrate.
adenylylation - ANSWERA covalent modification of an enzyme by addition of AMP that
serves to regulate catalytic activity.
, uridylylation - ANSWERA process that regulates enzyme activity by controlling
adenylylating and deadenylylating activity.
zymogens - ANSWERAn inactive enzyme precursor that is activated by a proteolytic
cleavage reaction. (aka proenzymes)
Enzyme activity in the cell is regulated by both bioavailability and catalytic efficiency.
Regulating enzyme bioavailability can be a rather slow process, but in contrast,
reversibly regulating the catalytic efficiency of an enzyme can be rapid and is an
efficient means to control signal transduction and metabolic processes tightly. The three
primary mechanisms of reversible regulation in the cell are competitive inhibition,
allosteric regulation, and most forms of covalent modification. - ANSWERHow is the
catalytic activity of an enzyme reversibly regulated to facilitate on/off control?
Tyr to Phe - ANSWERAn 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
B, C, A - ANSWERPut 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
D, C, A, B, F, E - ANSWERConstruct a functional signal transduction pathway by
placing the following actors in thecorrect order:A. upstream signaling proteinB. second
messengerC. receptor proteinD. first messengerE. target proteinsF. downstream
signaling protein
stimulator of cGMP phosphodiesterase - ANSWERMuscle relaxation in response to
nitric oxide would be reduced if a(n) __________ was present
receptor protein - ANSWERA protein that stimulates a cellular response after protein
structural changes initiated by binding of a ligand.
target proteins - ANSWERAn intracellular protein that is modified as a result of an
upstream signaling pathway.
covalent protein modifications, protein conformational changes, altered rates of protein
expression - ANSWERthe effect of activating a receptor protein involves one or more of
these biochemical responses
cell signaling pathway - ANSWERA linked set of biochemical reactions that are initiated
by ligand-induced activation of a receptor protein and terminated by a measurable
cellular response.
