BCH 369 Exam Questions| Already
Answered| GRADED A+
Activation of a G protein in response to hormone binding requires binding of _____ to the _____
subunit. A) GTP; β B) GDP; γ C) GTP; α D) GDP; α E) GDP; β - ANSWER-C) GTP
All known porins are _____ proteins composed of _____.
A) trimeric; four transmembrane α-helices
D) dimeric; three transmembrane α-helices
B) monomeric; seven transmembrane α-helices
E) trimeric; β-barrels
C) dimeric; β-barrels - ANSWER-E) trimeric; β-barrels
Which of the following must be known to calculate the kcat of an enzyme?
A) The KM for the substrate.
B) Vmax for the substrate, enzyme concentration and KM for the substrate.
C) Vmax for the substrate.
D) Enzyme concentration.
E) Vmax for the substrate and enzyme concentration. - ANSWER-E) Vmax for the substrate and enzyme
concentration.
A ligand that binds to a receptor to elicit a biological effect is known as a(n) A) antagonist B) agonist C)
protagonist D) inverse agonist - ANSWER-B) agonist
Metalloenzymes contain tightly bound metal ion cofactors.
A) True B) False - ANSWER-A) True
Which two curves, of the combinations listed, most accurately illustrate how the activity of an
allosteric enzyme differs in the absence and presence of an allosteric activator?
, A) Absence of activator, curve 2; presence of activator, curve 3.
B) Absence of activator, curve 1; presence of activator, curve 2.
C) Absence of activator, curve 3; presence of activator, curve 2.
D) Absence of activator, curve 3; presence of activator, curve 4. - ANSWER-C) Absence of activator, curve
3; presence of activator, curve 2.
Which of the following statements most accurately defines the term "antiport?"
A) A protein which transports two substances in opposite directions up (against) their concentation
gradients.
B) A protein which transports two substances in the same direction.
C) A protein which transports two substances in opposite directions.
D) A protein which transports two substances in the same direction up their concentation gradients. -
ANSWER-C) A protein which transports two substances in opposite directions.
Which of the following forms micelles spontaneously in water?
A) Cholesterol B) Fatty acids C) Glycerophospholipids D) Triacylglycerols - ANSWER-B) Fatty acids
Which of the following does NOT occur in biological signaling systems?
A) Ligand-protein interactions D) Protein-protein interactions
B) Autophosphorylation
E) All of the above processes may occur.
C) Opening or closing of ion channels - ANSWER-E) All of the above processes may occur.
For an enzyme that displays Michaelis-Menten kinetics, what is the effect of a competitive inhibitor on
Vmax? A) It increases B) It decreases C) There is no effect D) It may increase or decrease - ANSWER-C)
There is no effect
Mediated transport is classified into two categories: passive-mediated or active transport, depending
upon the rate of the reactions. A) True B) False - ANSWER-B) False
Answered| GRADED A+
Activation of a G protein in response to hormone binding requires binding of _____ to the _____
subunit. A) GTP; β B) GDP; γ C) GTP; α D) GDP; α E) GDP; β - ANSWER-C) GTP
All known porins are _____ proteins composed of _____.
A) trimeric; four transmembrane α-helices
D) dimeric; three transmembrane α-helices
B) monomeric; seven transmembrane α-helices
E) trimeric; β-barrels
C) dimeric; β-barrels - ANSWER-E) trimeric; β-barrels
Which of the following must be known to calculate the kcat of an enzyme?
A) The KM for the substrate.
B) Vmax for the substrate, enzyme concentration and KM for the substrate.
C) Vmax for the substrate.
D) Enzyme concentration.
E) Vmax for the substrate and enzyme concentration. - ANSWER-E) Vmax for the substrate and enzyme
concentration.
A ligand that binds to a receptor to elicit a biological effect is known as a(n) A) antagonist B) agonist C)
protagonist D) inverse agonist - ANSWER-B) agonist
Metalloenzymes contain tightly bound metal ion cofactors.
A) True B) False - ANSWER-A) True
Which two curves, of the combinations listed, most accurately illustrate how the activity of an
allosteric enzyme differs in the absence and presence of an allosteric activator?
, A) Absence of activator, curve 2; presence of activator, curve 3.
B) Absence of activator, curve 1; presence of activator, curve 2.
C) Absence of activator, curve 3; presence of activator, curve 2.
D) Absence of activator, curve 3; presence of activator, curve 4. - ANSWER-C) Absence of activator, curve
3; presence of activator, curve 2.
Which of the following statements most accurately defines the term "antiport?"
A) A protein which transports two substances in opposite directions up (against) their concentation
gradients.
B) A protein which transports two substances in the same direction.
C) A protein which transports two substances in opposite directions.
D) A protein which transports two substances in the same direction up their concentation gradients. -
ANSWER-C) A protein which transports two substances in opposite directions.
Which of the following forms micelles spontaneously in water?
A) Cholesterol B) Fatty acids C) Glycerophospholipids D) Triacylglycerols - ANSWER-B) Fatty acids
Which of the following does NOT occur in biological signaling systems?
A) Ligand-protein interactions D) Protein-protein interactions
B) Autophosphorylation
E) All of the above processes may occur.
C) Opening or closing of ion channels - ANSWER-E) All of the above processes may occur.
For an enzyme that displays Michaelis-Menten kinetics, what is the effect of a competitive inhibitor on
Vmax? A) It increases B) It decreases C) There is no effect D) It may increase or decrease - ANSWER-C)
There is no effect
Mediated transport is classified into two categories: passive-mediated or active transport, depending
upon the rate of the reactions. A) True B) False - ANSWER-B) False
