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Biochem Back Exams 4
Terms in this set (61)
Which statement concerning the mitochondrial F0F1 ATP synthase is FALSE?
the F1 subunit includes four sets of dimers
In which of the following locations do eukaryotes house the enzymes of the citric acid cycle?
Which of the following serves as a "swinging arm" when it transfers a reaction intermediate from one active site to the next?
Glycogen degradation is activated by
glucagon and epinephrine
Gluconeogenesis is decreased by
Which of the following is NOT true regarding the pentose phosphate pathway?
it generates NADPH for utilization by oxidative phosphorylation
Tricarboxylic acid cycle to be continuous requires the regeneration of
participates in the transport of electrons from organic substrates to oxygen in the respiratory chain of mitochondria
Where do the electrons from the NADH end up after electron transport in the mitochondria?
they reduce oxygen to water
How does cytochrome c shuttle electrons between Complexes III and IV?
it only loosely associates with the inner membrane and floats in the intermembrane space between the two protein complexes
Why does metabolic electron carrier NADH yield one more ATP than FADH2?
FADH2 donates electrons to Complex II, which doesn't pump protons across the mitochondrial inner membrane, whereas NADH donates to Complex I, which does pump protons
Uncoupling agents of oxidative phosphorylation
allow electron transport to continue but prevent the phosphorylation of ADP to ATP
the sites of regulation in the citric acid cycle involve reactions with large, negative deltaG values. These sites of regulation include
isocitrate dehydrogenase and citrate synthase
How man carbon atoms of an acetyl-CoA molecule are lost as CO2 during the first turn of the TCA cycle?
The first reaction of the tricarboxylic acid cycle, the citrate synthesis reaction, involves acetyl-CoA reacting with
The function of the enzyme dihydrolipoyl dehydrogenase (E3) is in the pyruvate dehydrogenase complex is to:
regenerate the oxidized lipoic acid cofactor bound to one of the other enzymes in the complex
What do the enzymes citrate synthase, isocitrate dehydrogenase, and a-ketoglutarate dehydrogenase have in common?
all are enzymes with large negative free energies
One turn of the citric acid cycle directly results in how many ATP or GTP molecules?
Which of the following enzymes utilizes biotin?
FADH2 is produced in the glycolytic pathway at the step catalyzed by which of the following enzymes?
pyruvate kinase is inhibited by which of the following molecules?
The reaction catalyzed by which of the following enzymes has the largest negative free energy?
Phosphofructokinase is regulated by all of the following except
Glucose is converted to which of the following high energy intermediates in glycolysis?
How many ATP molecules are synthesized by the aerobic metabolism of one glucose molecule in eukaryotes?
The first step in the breakdown of glycogen is catalyzed by
which of the following enzymes catalyzes the conversion of glucose-1-phosphate to glucose-6-phosphate?
Both glycogen synthesis and glycogen breakdown share the metabolite
A sample of glycogen from a patient with liver disease is incubated with Pi, normal glycogen phosphorylase, and normal debranching enzyme. The ratio of G1P to glucose formed in the reaction mixture is 100. What is the patients most probable enzymatic deficiency?
deficient branching enzyme
During glycolysis, the steps between glucose and formation of the triose phosphates
consume two ATP molecules
Which of the following metabolic conversions is considered to be the major control point of glycolysis?
the only membrane bound enzyme of the citric acid cycle is
the enzyme of the citric acid cycle, ____, contains an iron-sulfur cluster
the ______ produces the hormones insulin and glucagon
glycogen synthesis is activated by
starting with one glucose molecule in glycolysis and proceeding through the lactic acid fermentation in muscle, how many molecules of carbon dioxide are produced?
glycogen while being acted upon by active glycogen phosphorylase is converted first to
glucose-1-phosphate and glycogen with 1 glucose unit less
Which reaction in the electron transport chain and oxidative phosphorylation is irreversible?
Uncoupling agents are compounds that block ATP synthesis while allowing the respiration of the electron chain to continue. Which of the following would explain this?
they are compounds that move protons back across the inner mitochondrial membrane in the same direction as the proton gradient
Which complex along the electron transport chain does not contributed to the proton gradient?
chemiosmotic coupling describes
how the energy from the electron transport chain is used to generate an electrochemical gradient for protons, which is used to drive ATP synthesis
The primary function of the electron transport chain is
to move protons across the mitochondria inner membrane against their concentration gradient
pyruvate dehydrogenase is inhibited by high levels of
acetyl-CoA and NADH
reactions that replenish citric acid cycle intermediates are called
the succinyl-CoA synthase reaction used succinyl-CoA, a high energy intermediate, to produce succinate. This reaction also directly produces _____ in mammals.
Coenzymes involved in the reactions of the pyruvate dehydrogenase complex include all of the following except
Which of the following is a coenzyme involved in the conversion of succinate to fumarate in the tricarboxylic acid cycle?
Starting with one glucose molecule in glycolysis and proceeding through the citric acid cycle, how many molecules of CO2 are produced?
Which of the following molecules is capable of inhibiting pyruvate dehydrogenase, citrate synthase, isocitrate dehydrogenase, and a-ketoglutarate dehydrogenase?
Formation of lactate from pyruvate involves
the oxidation of NADH to NAD+
Dihydroxyacetone phosphate is substrate for which of the following enzymatic reactions?
triose phosphate isomerase
Which of the following molecules is a by-product of pyruvate metabolism under anaerobic conditions?
All of the following enzymes require Mg2+ except
fructose bisphosphate aldolase
Which of the following reactions commits the cell to glucose metabolism?
How many ATPs are synthesized for every cytoplasmic NADH that participates in the glycerophosphate shuttle in insect flight muscle?
How many NADH are produced when one acetyl group is oxidized in the citric acid cycle?
_____ is often referred to as a second messenger.
which of the following best describes the role of fructose-2,6-bisphosphate in liver cells)
potent allosteric activator of phosphofructokinase and an inhibitor of fructose bisphosphatase
Indicate the energy yield or cost, in ATP equivalents, for the following processes: glycogen (3 residues)--> 6 pyruvate
which of the following is a high-energy intermediate produced in glycolysis?
Which of the following enzymes catalyzes the transfer of a phosphoryl group from ATP to glucose?