Biochemistry Final Exam – Comprehensive Multiple-Choice Answer Key – university-level final exam in biochemistry

The glucose-alanine cycle is a method of transferring ammonia from the
skeletal muscle to the liver. In this process the non-toxic carrier of ammonia
is which of the following compounds? ~CORRECT ANSWER~✓✓Alanine



Which of the following enzymes is correctly paired with its activator?
~CORRECT ANSWER~✓✓N-acetylglutamate synthatase; arginine



The urea cycle takes place in which of the following subcellular locations?
~CORRECT ANSWER~✓✓the cytosol and the mitochondria



Which of the following enzymes is regulated by N-acetylglutamate
(NAGs)? ~CORRECT ANSWER~✓✓CPS I



Which of the following enzymes is the regulatory step in the urea cycle?
~CORRECT ANSWER~✓✓Carbamoyl phosphate synthetase I (CPS I)



Which of the following statements is consistent with nitrogen transport in
the fasted state? ~CORRECT ANSWER~✓✓The urea cycle will be active

,A comatose infant is brought to the ER. In the course of the examination,
plasma ammonia was found to be elevated 20-fold over normal values.
Urine orotic acid and uracil were both greater than normal. A defect of
which of the following enzymes is the most likely diagnosis? ~CORRECT
ANSWER~✓✓Ornithine transcarbamoylase



Your patient presents with a deficiency of the enzyme that catalyzes
synthesis of N-acetylglutamate (NAGs). Which of the following would be a
consequence of this deficiency in the patient? ~CORRECT
ANSWER~✓✓Increased amino acids in the blood



The cellular uptake of LDL increases intracellular cholesterol levels. This
has which of the following impacts on de novo cholesterol synthesis?
~CORRECT ANSWER~✓✓Increases degradation of HMG-CoA reductase



Dietary cholesterol is primarily transported in the body by which of the
following lipoproteins? ~CORRECT ANSWER~✓✓Chylomicron



Secondary bile salts are generated by bacterial modification of primary bile
salts in the intestinal lumen. These modifications have which of the
following impacts on bile salt solubility? ~CORRECT
ANSWER~✓✓Decrease solubility



A 47-year-old male is prescribed a statin (HMG-CoA reductase inhibitor) to
manage his elevated LDL cholesterol. What is the initial mechanism of

,action for obtaining the desired effect in this man? ~CORRECT
ANSWER~✓✓Decreasing hepatic cholesterol biosynthesis



A deficiency in the LDL receptor will result in an initial decrease in which
of the following? ~CORRECT ANSWER~✓✓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? ~CORRECT
ANSWER~✓✓Low blood LDLs



A 45-year-old man is found to have an elevated serum triglycerides of >
730mg/dL. He tells you he forgot to fast before his visit and he ate a full
breakfast of bacon and eggs before the labs were drawn. Which of the
following lipoproteins would be the largest contributors to a measurement
of plasma triglycerides in this situation? ~CORRECT
ANSWER~✓✓Chylomicrons and VLDLs



In the reaction catalyzed by cholesterol ester transfer protein (CETP), the
VLDL particle receives which of the following compounds from HDL
particles? ~CORRECT ANSWER~✓✓Cholesterol-ester



In reverse cholesterol transport HDL interacts with the ABCA1 transporter
to move cholesterol from the cell to the HDL. This also requires the activity

, of which of the following enzyme? ~CORRECT ANSWER~✓✓Lecithin
cholesterol acyltransferase (LCAT)



HDL particles interact with VLDL particles to exchange cholesterol ester
for triacylglyerols. Which of the following enzymes is responsible for this
process? ~CORRECT ANSWER~✓✓Cholesterol ester transfer protein
(CETP)



Which of the following is a major source of extracellular cholesterol for
human tissues? ~CORRECT ANSWER~✓✓LDLs



An individual is suspected of having a deficiency in branched chain keto
acid dehydrogenase. Supplementation of which of the following vitamins
or cofactors may help resolve this issue? ~CORRECT
ANSWER~✓✓Thiamine



A 55-year old man presents to his primary care physician with bouts of
dizziness and confusion. He is diagnosed with hyperhomocysteinemia due
to a deficiency of cystathionine-ß synthase. In this individual which of the
following amino acids could potentially become essential? ~CORRECT
ANSWER~✓✓Cysteine



Phenylketonuria can be caused by an enzymatic deficiency or it can present
due to a deficiency in which of the following required metabolic cofactors?
~CORRECT ANSWER~✓✓Tetrahydrobiopterin (BH4)