BIOCHEM MODULE 1 EXAM | ALL QUESTIONS
AND CORRECT ANSWERS | GRADED A+ |
VERIFIED ANSWERS | LATEST VERSION
Which of the following produces the largest number of reducing equivalents
when oxidized?
A) Glucose
B) NADPH
C) NADH
D) Palmitic acid
E) A hydrogen atom ------CORRECT ANSWER---------------D) Palmitic acid
ATP has a high phosphoryl group transfer potential because:
A) it is chemically unstable.
B) it has a high rate of spontaneous hydrolysis at physiological pH and
temperature.
C) it exhibits resonance stabilization prior to hydrolysis.
D) it has three phosphate groups.
E) cleavage of either of its two phosphoanhydride bonds proceeds with a
large negative △Go' of hydrolysis ------CORRECT ANSWER---------------E)
cleavage of either of its two phosphoanhydride bonds proceeds with a large
negative △Go' of hydrolysis
Substrate-level phosphorylation is a term given to the loss of free energy
when ATP is hydrolyzed. ------CORRECT ANSWER---------------False
The main energy-coupling compound in biochemical reactions that allows
thermodynamically unfavorable processes to become favorable is
________. ------CORRECT ANSWER---------------ATP
,Under physiological conditions the complete oxidation of glucose to carbon
dioxide and water in the presence of oxygen has a △G of -2900 kJ/mol
glucose. This process can be coupled to the synthesis of ~32 mol ATP.
The △G of the coupled reactions to make ATP is -1300 kJ/mol glucose.
Calculate the △G for the synthesis of ATP from ADP ------CORRECT
ANSWER---------------+50kJmol^-1
Which of the following can be used as a metabolic control mechanism?
A) Enzyme compartmentation
B) Action of hormones
C) Covalent modification of an enzyme
D) Regulation of enzyme degradation
E) All of the above ------CORRECT ANSWER---------------E) All of the above
A futile cycle is:
A) the citric acid cycle.
B) two reactions or pathways that share substrates and products, and
result in no net gain of ATP.
C) two opposing cellular reactions that are independently controlled.
D) an endergonic reaction that uses up ATP.
E) the reoxidation of NAD+ from NADH ------CORRECT ANSWER------------
---B) two reactions or pathways that share substrates and products, and
result in no net gain of ATP.
Enzyme-catalyzed sequential reactions that make up a metabolic pathway
are normally separated in the cell for equal access to reactants ------
CORRECT ANSWER---------------False
Reactions in metabolic pathways that are subject to regulation are those
that are displaced far from ________. ------CORRECT ANSWER--------------
-equilibrium
,An enzyme that catalyzes a committed step in a metabolic pathway has a
high ________. ------CORRECT ANSWER---------------flux control coefficient
The standard free energy change in physiological conditions (△G∘') for the
reaction catalyzed by malate dehydrogenase in the citric acid cycle
malate + NAD+ oxaloacetate + NADH + H+
is ~+29 kJmol^-1
Calculate the actual △G' at 37∘C if Keq' is 1.02 × 10^-5 ------CORRECT
ANSWER----------------0.62 kJmol^-1
Anaerobic glycolysis can produce ATP at a much faster rate than aerobic
oxidative phosphorylation ------CORRECT ANSWER---------------True
Which of the following types of reaction does NOT occur in glycolysis?
A) Isomerization
B) Nucleophilic attack
C) Aldol condensation
D) Oxidation
E) Dehydration ------CORRECT ANSWER---------------C) Aldol condensation
The standard free energy change of the glycolytic pathway to pyruvate is -
79.9 kJ/mol, while the standard free energy change associated with
gluconeogenesis from pyruvate is -42.7 kJ/mol. What would the standard
free energy change be for a direct reversal of the glycolytic pathway ------
CORRECT ANSWER---------------+79.9kJ/mol
Glycolysis is regulated primarily by:
, A) the availability of glucose-6-phosphate.
B) three strongly endergonic, nonequilibrium reactions.
C) three strongly exergonic, nonequilibrium reactions.
D) allosteric effectors of pyruvate kinase.
E) phosphorylation of phosphofructokinase ------CORRECT ANSWER-------
--------C) three strongly exergonic, nonequilibrium reactions
Which of the following statements about regulation of phosphofructokinase
is FALSE?
A) AMP is an activator.
B) ADP is an activator.
C) Citrate is an inhibitor.
D) Fructose 2,6-bisphosphate is an activator.
E) ATP decreases the apparent Km for fructose-6-phosphate ------
CORRECT ANSWER---------------E) ATP decreases the apparent Km for
fructose-6-phosphate
Liver pyruvate kinase is activated by dephosphorylation in response to
glucagon ------CORRECT ANSWER---------------False
Hexokinase, phosphofructokinase and pyruvate kinase are each subject to
________ control ------CORRECT ANSWER---------------allosteric
Fructose-1,6-bisphosphate is a feedforward ________ activator of liver
pyruvate kinase ------CORRECT ANSWER---------------allosteric
The oxidation of glucose to lactate has a standard free energy change of
approximately -196 kJ/mol. Calculate the efficiency of energy conversion if
the standard free energy change for the production of ATP from ADP and
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