UNE Medical Biochem Final Exam Questions With Solved
Answers Scored A+
The cellular uptake of LDL increase intracellular cholesterol levels. This has
which of the following impacts on de novo cholesterol synthesis?
Increases degradation of HMG-CoA reductase
Dietary cholesterol is primarily transported in the body by which of the following
lipoproteins?
Chylomicrons.
Cholesterol and TG from diet are transported from intestine to liver via chylomicrons.
The LDL receptor is also highly regulated in the cell. Which of the following
proteins targets the LDL receptor for degradation?
Proprotein converts subtillisin/kexin type 9 (PSK9)
Bile salts are synthesized from cholesterol and are used for the emulsification of
dietary lipids. What is the primary fate of bile salts during digestion?
They are absorbed in the ileum.
Secondary bile salts are excreted in the feces.
A deficiency in the LDL receptor will result in an initial decrease in which of the
following?
Intracellular cholesterol
A 45-year-old man has a mild heart attack and a history of vascular disease. He is
placed on a Mediterranean diet and statin drug therapy. Which of the following
will be the most likely result of this drug therapy?
Low blood LDLs
Statins: directly reduce de novo cholesterol synthesis and increase LDL receptor
expression-->increase LDL uptake and reduce circulating levels of LDLs
Secondary bile salts lack a hydroxyl (OH) group when compared to primary bile
salts. What is the consequence of the loss of this group?
Secondary bile salts are less soluble.
Less likely to be absorbed.
Which of the following is NOT required for the transport of newly synthesized
fatty acids to the adipose?
Carnitine to shuttle the fatty acids out of the mitochondria.
Carnitine shuttle is required for the process of beta-oxidation to transport fatty acyl
chains into the mito.
What is the primary component of a VLDL particle?
Triagcylglycerols
From de novo synthesis in the liver.
, A 5-year-old presents to her primary care physician. Her mother is concerned due
to persistent diarrhea which is worse when eating fatty foods. The child also has
some clinical signs of a deficiency in vitamins A, D, E, and K (fat soluble
vitamins). Based on this information, the child likely has a deficiency in the ability
to synthesize which of the following lipoproteins?
Chylomicrons
Chylomicrons transport dietary fats and fat soluble vitamins.
VLDL particles have which of the following combinations of apoproteins in their
mature form?
ApoB100, ApoCII, ApoE
Which of the following is the major source of extracellular cholesterol for human
tissues?
LDLs
Primary role of LDL: transport cholesterol to peripheral tissues
The interaction of chylomicrons with lipoprotein lipase is stimulated by which of
the following Apo proteins?
ApoC II
Apo C II is acquired from an interaction with HDL and is required to activate lipoprotein
lipase. Phospholipids are also required for this activation.
Shortly after meal high in fat you would expect an elevation of which of the follow
lipoproteins in circulation?
Chylomicrons
A 45-year old man is found to have an elevated serum cholesterol of 300mg/dL
after a 12 hr. fast. Which of the following lipoproteins would be the largest
contributors to a measurement of plasma cholesterol in a normal person
following a 12 hour fast?
HDLs and LDLs
Both LDL and HDL are the major carriers of cholesterol in circulation. VLDLs would be
the best represented of serum triglycerides.
Which of the following is the regulatory enzyme for fatty acid synthesis?
Acetyl CoA carboxylase
Step: synthesis of malonyl coA
Uses CO2 and biotin to add carbon to cytosolic acetyl CoA
Which of the following is the regulated step of lipogenesis in eukaryotes?
Carboxylation of acetyl CoA
A defect in the thioesterase subunit of fatty acid synthase would impair which of
the following activities of the enzyme complex?
Liberation of newly assembled palmitate from the enzyme.
Fatty acid synthase is a multimeric enzyme and the final and sixth enzyme in the chain
is the thioesterase which will liberate the newly formed palmitate.
Answers Scored A+
The cellular uptake of LDL increase intracellular cholesterol levels. This has
which of the following impacts on de novo cholesterol synthesis?
Increases degradation of HMG-CoA reductase
Dietary cholesterol is primarily transported in the body by which of the following
lipoproteins?
Chylomicrons.
Cholesterol and TG from diet are transported from intestine to liver via chylomicrons.
The LDL receptor is also highly regulated in the cell. Which of the following
proteins targets the LDL receptor for degradation?
Proprotein converts subtillisin/kexin type 9 (PSK9)
Bile salts are synthesized from cholesterol and are used for the emulsification of
dietary lipids. What is the primary fate of bile salts during digestion?
They are absorbed in the ileum.
Secondary bile salts are excreted in the feces.
A deficiency in the LDL receptor will result in an initial decrease in which of the
following?
Intracellular cholesterol
A 45-year-old man has a mild heart attack and a history of vascular disease. He is
placed on a Mediterranean diet and statin drug therapy. Which of the following
will be the most likely result of this drug therapy?
Low blood LDLs
Statins: directly reduce de novo cholesterol synthesis and increase LDL receptor
expression-->increase LDL uptake and reduce circulating levels of LDLs
Secondary bile salts lack a hydroxyl (OH) group when compared to primary bile
salts. What is the consequence of the loss of this group?
Secondary bile salts are less soluble.
Less likely to be absorbed.
Which of the following is NOT required for the transport of newly synthesized
fatty acids to the adipose?
Carnitine to shuttle the fatty acids out of the mitochondria.
Carnitine shuttle is required for the process of beta-oxidation to transport fatty acyl
chains into the mito.
What is the primary component of a VLDL particle?
Triagcylglycerols
From de novo synthesis in the liver.
, A 5-year-old presents to her primary care physician. Her mother is concerned due
to persistent diarrhea which is worse when eating fatty foods. The child also has
some clinical signs of a deficiency in vitamins A, D, E, and K (fat soluble
vitamins). Based on this information, the child likely has a deficiency in the ability
to synthesize which of the following lipoproteins?
Chylomicrons
Chylomicrons transport dietary fats and fat soluble vitamins.
VLDL particles have which of the following combinations of apoproteins in their
mature form?
ApoB100, ApoCII, ApoE
Which of the following is the major source of extracellular cholesterol for human
tissues?
LDLs
Primary role of LDL: transport cholesterol to peripheral tissues
The interaction of chylomicrons with lipoprotein lipase is stimulated by which of
the following Apo proteins?
ApoC II
Apo C II is acquired from an interaction with HDL and is required to activate lipoprotein
lipase. Phospholipids are also required for this activation.
Shortly after meal high in fat you would expect an elevation of which of the follow
lipoproteins in circulation?
Chylomicrons
A 45-year old man is found to have an elevated serum cholesterol of 300mg/dL
after a 12 hr. fast. Which of the following lipoproteins would be the largest
contributors to a measurement of plasma cholesterol in a normal person
following a 12 hour fast?
HDLs and LDLs
Both LDL and HDL are the major carriers of cholesterol in circulation. VLDLs would be
the best represented of serum triglycerides.
Which of the following is the regulatory enzyme for fatty acid synthesis?
Acetyl CoA carboxylase
Step: synthesis of malonyl coA
Uses CO2 and biotin to add carbon to cytosolic acetyl CoA
Which of the following is the regulated step of lipogenesis in eukaryotes?
Carboxylation of acetyl CoA
A defect in the thioesterase subunit of fatty acid synthase would impair which of
the following activities of the enzyme complex?
Liberation of newly assembled palmitate from the enzyme.
Fatty acid synthase is a multimeric enzyme and the final and sixth enzyme in the chain
is the thioesterase which will liberate the newly formed palmitate.
