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α-ketoglutarate dehydrogenase is the enzyme responsible for one of the irreversible reactions in the TCA
cycle. The enzyme catalyzes which of the following conversions?
Acetyl-CoA to citrate
Succinyl-CoA to succinate
α-ketoglutarate to succinyl-
CoA
Citrate to isocitrate
Which of the following intermediates of the TCA cycle is required in the cytosol for fatty acid synthesis?
Succinyl-CoA
Citrate
Isocitrate
α-ketoglutarate
Which of the following best describes the net effect of the 8 steps of the TCA cycle?
This process completely oxidizes an acetyl group to carbon
dioxide.
This process directly converts pyruvate to succinate.
This process produces NAD
and Q.
This process directly produces ATP for the cell.
A patient presents with a deficiency of thiamine. If this patient’s liver cells are compared with normal cells,
which of the following products would be decreased in the thiamine-deficient cell (when compared to the
normal cells) if the cells are only given glucose as a fuel?
Alanine
CO
Lactate
NADP
Pyruvate
In order for glucose to be retained within the cell, which of the following modifications must occur?
Methylation
Phosphorylation
Ionization
Acetylation
A farmer finds a cow dead in his field and notices an unusual plant nearby. Autopsy results show an
elevated level of citrate present in the cow’s mitochondria. This data collectively suggest inhibition of
which of the following enzymes?
Aconitase
Citrate lyase
Pyruvate dehydrogenase
complex
Malate dehydrogenase
A 10-year-old girl is swimming in a local competition. The intense exercise will increase intracellular
calcium levels which in turn will increase flux through the TCA cycle by stimulating the activity of all of the
following enzymes EXCEPT?
α-ketoglutarate dehydrogenase
Pyruvate dehydrogenase
Which of the following is a characteristic of all receptors?
They must sit on the plasma membrane
They will initially elicit a transcriptional response
Their activity can be terminated through
phosphorylation
They are specific to a chemical messenger
A patient is found to have a rare disease in which the secretory function of the α-cells of the pancreas is
impaired. As a consequence, glucagon cannot be secreted. Direct stimulation of which of the following
pathways in liver will be impaired?
Citric acid cycle (TCA)
Glycogenesis
Glycolysis
Pentose phosphate
pathway
Gluconeogenesis
A novel signaling cascade is discovered that you suspect activates a G-αs subunit. Which of the following
downstream events would be consistent with this discovery?
Activation of adenylyl cyclase
Decreased synthesis of cAMP
Inhibition of adenylyl cyclase
Activation of
phosphodiesterase
Which of the following pathways is not stimulated by high levels of insulin?
Glycolysis
Glycogen synthesis
Amino acid
catabolism
Fatty acid synthesis
Which of the following is an insulin insensitive GLUT transporter found primarily on the liver?
GLUT
GLUT
GLUT
GLUT
Which of the following hormones is best described as anabolic?
Epinephrine
Insulin
Cortisol
Glucagon
When insulin levels are high, which of the following is true?
Glycogen synthase is phosphorylated and active
Glycogen phosphorylase is dephosphorylated and
active
Pyruvate carboxylase
Transketolase
Amino transferase
Glycogenolysis and glycogen synthesis are regulated in such a way that neither process is active at the
same time. During the fasted state, (ratio of insulin to glucagon is low) which of the following best
characterizes the regulation of these pathways?
Glycogen phosphorylase is dephosphorylated and glycogen synthase is
phosphorylated
Both glycogen phosphorylase and glycogen synthase are phosphorylated
Glycogen phosphorylase is phosphorylated and glycogen synthase is
dephosphorylated
Both glycogen phosphorylase and glycogen synthase are dephosphorylated
Which of the following enzymes is used by the gluconeogenic pathway but not the glycolytic pathway?
Phosphoenolpyruvate carboxykinase
(PEPCK)
Glyceraldehyde-3-phosphate dehydrogenase
Hexokinase
Pyruvate kinase
During an overnight fast, which of the following is the major source of blood glucose?
Gluconeogenesis
Hepatic glycogenolysis
Glycerol from lipolysis
Muscle glycogenolysis
Dietary glucose from the
intestine
Which of the following cofactors is required for transketolase activity?
Thiamine
diphosphate
Biotin
Pyridoxal phosphate
NAD
Which of the following enzymes is involved in the non-oxidative portion of the Pentose Pathway?
Glucose 6-phosphate
dehydrogenase
Aldolase B
Galactokinase
Transaldolase
UDP-glucose is required for glycogen synthesis and which of the following pathways?
Fructose metabolism
Pentose Phosphate
Pathway
Glycolysis
Galactose metabolism
Which of the following are the two primary products of the pentose phosphate pathway?
Inability to metabolize fructose
Hypoglycemia
The presence of reducing sugar in the
urine
