UNE CHEM 1005 Midterm Study Guide Questions With
Correct Answers.
What enzyme is used by the gluconeogenic pathway but NOT in the glycolytic
pathway?
Phosphoenolpyruvate Carboxykinase PEPCK
Newborn screening results show a biotinidase deficiency in a 2 day old infant.
The deficiency impairs the infant's ability to reuse and recycle biotin. Due to the
enzymatic deficiency, the activity of what enzyme is likely impaired?
Pyruvate carboxylase
If unregulated, which of the following pairs of enzymes would represent a futile
cycle?
Fructose 1,6 -bisphosphate and phosphofructokinase-1
When cortisol binds to its receptor, which of the following events occur top
stimulate gluconeogenesis?
Enhanced transcription of regulatory enzymes
What compound allosterically activates pyruvate carboxylase
Acetyl-CoA
When the insulin to glucagon ratio is low, glycogenolysis is activated in the liver.
Which of the following is primary fate of the glucose 6-phosphate released under
these conditions?
Dephosphorylated and released into the blood to maintain blood glucose
What are the two major contributors to maintaining blood glucose levels during
fasting?
Hepatic glycogenolysis and gluconeogenesis
Pyruvate dehydrogenase complex is highly regulated. The enzyme that will be
most active when which of the following compounds is high?
Pyruvate
A deficiency in thiamine can reduce the activity of the pyruvate dehydrogenase
complex. Under these conditions, you would expect a higher than normal blood
concentration of which of the following metabolites?
Pyruvate
A-ketoglutarate dehydrogenase is the enzyme responsible for one of the
irreversible reactions in the TCA cycle, What conversion does it catalyze?
A-ketoglutarate to succinyl-CoA
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 thru the TCA
cycle by stimulating the activity of all of the following enzymes EXCEPT
Succinate Thiokinase
TCA Cycle intermediates are always being removed for various reasons but the
cycle does not run out of intermediates and stop. This is because the TCA cycle
can replenish intermediates thru
Using anaplerotic reactions
A 10-year old boy is playing soccer and is sprinting after the ball. Under these
anaerobic conditions, glucose oxidation primarily results in an increase in
, Lactate
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
Which of the following reactions is commonly used to replenish intermediates of
the TCA cycle
Glutamate to A-ketoglutarate
Within the red blood cell, NADPH is used
to re-reduce glutathione
In the non-oxidative portion of the pentose phosphate pathway, 2-carbon
fragments of keto-sugar can be transferred to other sugars to generate a larger
sugar molecule. The reaction is catalyzed by which of the following enzymes?
Transketolase
Two primary products of the Pentose Phosphate Pathway
Ribose-5-phosphate and NADPH
The major regulatory step of the pentose phosphate pathway is catalyzed by
Glucose 6-phosphate dehydrogenase
Cofactor required for transketolase activity
Thiamine diphosphate
A deficiency in glucose-6-phosphate dehydrogenase reduces the levels of
NADPH in the red blood cell. This leads to an increase in what compound?
Oxidized Glutathione
An 18-month old is diagnosed with hereditary fructose intolerance (deficiency of
aldolase B). Lab testing showed low blood glucose levels at the time of
presentation. This is likely due to the accumulation of fructose-1-phosphate and
inhibition of what pathway?
Gluconeogenesis and glycogenolysis
Shortly after a meal there will be increased activity in which of the following
pathways as a result of increased insulin?
Glycolysis
A novel signaling cascade is discovered that you suspect activates G-As
subunits. What downstream event would be consistent with this discovery?
Activation of adenylyl cyclase
A young woman goes to work without eating breakfast and lunch. What pathway
is providing substrates used to generate ATP in the liver?
Free Fatty Acids
What is the primary oxidized fuel for skeletal muscle in the fasted state?
Free Fatty Acids
A teenage female presenting with lack of menstration (amenorhea) is found to
have a dysfunctional steroid receptor characteristic of androgen insensitivity
syndrome. What accurately describes steroid hormones?
They enhance transcription when bound to receptors
Steroid hormones bind what type of receptor?
Intracellular receptors
Which of the following statements is consistent with the actions of epinephrine?
Enhances glucose output from the liver under stressful situations
Correct Answers.
What enzyme is used by the gluconeogenic pathway but NOT in the glycolytic
pathway?
Phosphoenolpyruvate Carboxykinase PEPCK
Newborn screening results show a biotinidase deficiency in a 2 day old infant.
The deficiency impairs the infant's ability to reuse and recycle biotin. Due to the
enzymatic deficiency, the activity of what enzyme is likely impaired?
Pyruvate carboxylase
If unregulated, which of the following pairs of enzymes would represent a futile
cycle?
Fructose 1,6 -bisphosphate and phosphofructokinase-1
When cortisol binds to its receptor, which of the following events occur top
stimulate gluconeogenesis?
Enhanced transcription of regulatory enzymes
What compound allosterically activates pyruvate carboxylase
Acetyl-CoA
When the insulin to glucagon ratio is low, glycogenolysis is activated in the liver.
Which of the following is primary fate of the glucose 6-phosphate released under
these conditions?
Dephosphorylated and released into the blood to maintain blood glucose
What are the two major contributors to maintaining blood glucose levels during
fasting?
Hepatic glycogenolysis and gluconeogenesis
Pyruvate dehydrogenase complex is highly regulated. The enzyme that will be
most active when which of the following compounds is high?
Pyruvate
A deficiency in thiamine can reduce the activity of the pyruvate dehydrogenase
complex. Under these conditions, you would expect a higher than normal blood
concentration of which of the following metabolites?
Pyruvate
A-ketoglutarate dehydrogenase is the enzyme responsible for one of the
irreversible reactions in the TCA cycle, What conversion does it catalyze?
A-ketoglutarate to succinyl-CoA
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 thru the TCA
cycle by stimulating the activity of all of the following enzymes EXCEPT
Succinate Thiokinase
TCA Cycle intermediates are always being removed for various reasons but the
cycle does not run out of intermediates and stop. This is because the TCA cycle
can replenish intermediates thru
Using anaplerotic reactions
A 10-year old boy is playing soccer and is sprinting after the ball. Under these
anaerobic conditions, glucose oxidation primarily results in an increase in
, Lactate
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
Which of the following reactions is commonly used to replenish intermediates of
the TCA cycle
Glutamate to A-ketoglutarate
Within the red blood cell, NADPH is used
to re-reduce glutathione
In the non-oxidative portion of the pentose phosphate pathway, 2-carbon
fragments of keto-sugar can be transferred to other sugars to generate a larger
sugar molecule. The reaction is catalyzed by which of the following enzymes?
Transketolase
Two primary products of the Pentose Phosphate Pathway
Ribose-5-phosphate and NADPH
The major regulatory step of the pentose phosphate pathway is catalyzed by
Glucose 6-phosphate dehydrogenase
Cofactor required for transketolase activity
Thiamine diphosphate
A deficiency in glucose-6-phosphate dehydrogenase reduces the levels of
NADPH in the red blood cell. This leads to an increase in what compound?
Oxidized Glutathione
An 18-month old is diagnosed with hereditary fructose intolerance (deficiency of
aldolase B). Lab testing showed low blood glucose levels at the time of
presentation. This is likely due to the accumulation of fructose-1-phosphate and
inhibition of what pathway?
Gluconeogenesis and glycogenolysis
Shortly after a meal there will be increased activity in which of the following
pathways as a result of increased insulin?
Glycolysis
A novel signaling cascade is discovered that you suspect activates G-As
subunits. What downstream event would be consistent with this discovery?
Activation of adenylyl cyclase
A young woman goes to work without eating breakfast and lunch. What pathway
is providing substrates used to generate ATP in the liver?
Free Fatty Acids
What is the primary oxidized fuel for skeletal muscle in the fasted state?
Free Fatty Acids
A teenage female presenting with lack of menstration (amenorhea) is found to
have a dysfunctional steroid receptor characteristic of androgen insensitivity
syndrome. What accurately describes steroid hormones?
They enhance transcription when bound to receptors
Steroid hormones bind what type of receptor?
Intracellular receptors
Which of the following statements is consistent with the actions of epinephrine?
Enhances glucose output from the liver under stressful situations
