Intro to Biochemistry (MURPHY 301) CH
12 - 14, exam 2 biochem, Biochem Test 2,
Module 3 Biochem
Anaerobic glycolysis can produce ATP at a much faster rate than aerobic oxidative
phosphorylation.
True or False? - ANS 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 - ANS 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. -
ANS +79.9 kJ/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. - ANS 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. - ANS ATP decreases the
apparent Km for fructose-6-phosphate.
,Liver pyruvate kinase is activated by dephosphorylation in response to glucagon.
True or False - ANS False
Hexokinase, phosphofructokinase and pyruvate kinase are each subject to ________ control. -
ANS allosteric
Fructose-1,6-bisphosphate is a feedforward ________ activator of liver pyruvate kinase. - ANS
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 inorganic phosphate is +32.2 kJ/mol. - ANS 33.8%
All of the reactions of both glycolysis and gluconeogenesis occur in the cytosol.
True or False - ANS False
The flux rate through the gluconeogenic pathway is directly proportional to the amount of
carbohydrate in the diet.
True or False - ANS False
Much of the regulation of gluconeogenesis is a result of the inhibition of glycolysis
True or False - ANS True
Which of the following cannot be used as a precursor for gluconeogenesis?
A) Glycerol
B) Pyruvate
C) Lactate
D) Leucine
E) Alanine - ANS Leucine
Flux through the pentose phosphate pathway is controlled mainly by the NADP+/NADPH ratio in
the cell
True or False - ANS True
The primary gluconeogenic organ in animals is:
A) skeletal muscle.
B) kidney medulla.
, C) kidney cortex.
D) liver.
E) heart muscle. - ANS Liver
________ from muscle working anaerobically is released to blood and can be taken up by liver
where it is converted to pyruvate by the enzyme lactate dehydrogenase. - ANS Lactate
The Pasteur effect describes the observation that yeast-metabolizing glucose anaerobically will
dramatically increase their rate of glucose utilization when provided with air
True or False - ANS False
Both glycolysis and gluconeogenesis are controlled by fructose 2,6-bisphosphate in response to
hormones.
True or False - ANS True
Pyruvate carboxylase and phosphoenolpyruvate carboxykinase catalyze reactions of
gluconeogenesis that bypass the reaction of glycolysis that is catalyzed by _______ _____. -
ANS pyruvate kinase
Glycogen is a major energy source for skeletal muscle contraction.
True or False - ANS True
Polysaccharide digestion and glycogen breakdown involve sequential cleavage from ________
ends of glucose polymers. - ANS Non-reducing
The major product from the action of glycogen phosphorylase and the debranching enzyme
glucantransferase is ________. - ANS glucose-1-phosphate
Which of the following is NOT involved in glycogen synthesis?
A) UDP-glucose
B) Glycogenin
C) Amylo-(1,4 to 1,6)-transglycosylase
D) Glycogen synthase
E) Glycogen phosphorylase - ANS glycogen phosphorylase
Which statement about control of glycogen metabolism is INCORRECT?
A) Epinephrine signals glycogen breakdown in muscle.
B) Glucagon signals glycogen breakdown in liver.
C) Glycogen phosphorylase is activated by phosphorylation.
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