UNE BIOCHEMISTRY FINAL EXAM ACTUAL QUESTIONS
AND ANSWERS GUARANTEE A+
✔✔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? - ✔✔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? -
✔✔Cholesterol ester transfer protein (CETP)
✔✔Which of the following is a major source of extracellular cholesterol for human
tissues? - ✔✔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? - ✔✔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? - ✔✔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? -
✔✔Tetrahydrobiopterin (BH4)
✔✔A 17-year old female presents to her primary care and is diagnosed with a Vitamin
B12 (cobalamin) deficiency. In this individual, which of the following reactions would be
compromised? - ✔✔Conversion of methyl malonyl-Co A to succinyl-CoA
✔✔A 15-year-old female presents to her pediatrician with concerns over her inability to
sleep, increased feelings of depression and generalized fatigue. A full laboratory work-
up is ordered and based on these findings she is diagnosed with a melatonin deficiency.
Based on this information, metabolism of which of the following amino acids is likely
impaired? - ✔✔Tryptophan
✔✔A 52-year- old male sought medical help complaining about progressive appearance
of hyperchromic (hyper pigmented) papules on the edge of the second finger of both
hands. He also complained about darkening of urine. Incisional biopsy of one of the
spots on his hands and urine sample tested positive for or homogentisic acid. Based on
these findings a diagnosis of alkaptonuria is made. This diagnosis is consistent with a
deficiency in which of the following enzymes? - ✔✔Homogentisate oxidase
,✔✔Methotrexate is a potent anticancer agent that starves dividing cells of
deoxyribonucleotides through direct inhibition of which of the following processes? -
✔✔Metabolism of folic acid
✔✔A 47-year-old man complains of pain in the joints of his left big toe, which are
obviously swollen and tender. The pain has been chronic but became intolerable the
day after Thanksgiving when he had a large meal and several glasses of red wine.
Based on this information a diagnosis of gout is made. Which of the following is involved
in the pathophysiology of this patient's condition? - ✔✔Elevated uric acid
✔✔Which of the following is the common intermediate for purine synthesis? -
✔✔Inosine monophosphate
✔✔The ribonucleotide reductase is important for converting ribose bases to the deoxy
form. This conversion is coupled with the oxidation of which of the following
compounds? - ✔✔Thioredoxin
✔✔In pyrimidine synthesis, carbamoyl phosphate synthetase II (CPSII) can be
allosterically activated by which of the following compounds? - ✔✔5-phosphoribosyl 1-
pyrophosphate (PRPP)
✔✔Which of the following enzymes is used directly in the synthesis of dTMP
(thymidine)? - ✔✔Thymidylate synthase
✔✔The regulation of PRPP synthetase is critical in the production of both purines and
pyrimidines. This enzyme is inhibited under which of the following conditions? -
✔✔When both GDP and ADP are elevated
✔✔A 4-year-old girl presented to the clinic with megaloblastic anemia and failure to
thrive. Urinalysis showed significant sediment with extremely high levels of orotic acid. A
deficiency in which of the following enzymes would be consistent with this presentation?
- ✔✔Orotate phosphoribosyltransferase
✔✔The transamination of all amino acids requires which of the following cofactors? -
✔✔Pyridoxal phosphate (PLP)
✔✔Ubiquitination is a means of targeting a protein for which of the following cellular
processes? - ✔✔Proteasomal degradation
✔✔Which of the following reactions of the urea cycle takes place in the mitochondria? -
✔✔The synthesis of carbamoyl phosphate
, ✔✔Several amino acids are intermediates of the urea cycle, having side ammonia
groups that join with free carbon dioxide (CO2) and ammonia to produce net excretion
of ammonia as urea. Which of the following amino acids has a nitrogen in its side chain
and is an intermediate of the urea cycle? - ✔✔Arginine
✔✔Homocystinuria can be caused by several different enzyme or vitamin deficiencies.
An elevation of homocysteine and a decrease in cysteine would most likely present due
to which of the following deficiencies? - ✔✔Loss of function of cystathionine-β synthase
✔✔In an individual with a deficiency in the branched chain ketoacid dehydrogenase
complex, metabolism of which of the following amino acids would not likely be
impaired? - ✔✔Tyrosine
✔✔S-adenosylmethionine (SAM) is synthesized from ATP and methionine. A deficiency
in which of the following enzymes would impair the production of SAM? - ✔✔Methionine
adenosyltransferase (MAT)
✔✔The conversion of ribose bases into deoxy-bases will be occurring under which of
the following conditions? - ✔✔When cells are proliferating
✔✔A patient recently diagnosed with colon cancer is being treated with 5-fluorouracil.
Which of the following enzymes will this drug directly inhibit? - ✔✔Thymidylate synthase
✔✔An elevation of purine nucleotides will negatively regulate pyrimidine synthesis
through which of the following mechanisms? - ✔✔Inhibiting the activity of carbamoyl
phosphate synthetase II
✔✔Purine biosynthesis starts with the activation of a 5-carbon sugar. In this initial
reaction, ribose 5-phosphate is converted into which of the following compounds? -
✔✔PRPP (5- phosphoribosylpyrophosphate)
✔✔A 40-year-old male comes in to the doctor's office with severe pain in his big toe. He
is diagnosed with gout. Allopurinol is administered and this drug will inhibit which of the
following enzymes? - ✔✔Xanthine oxidase
✔✔In the salvage of purines, hypoxanthine-guanine phosphoribosyl transferase
(HGPRT) is responsible for which of the following processes? - ✔✔Conversion of
guanine to guanosine monophosphate (GMP)
✔✔In the case of a deficiency of biotin, which of the following enzymes required for fatty
acid metabolism will be impaired? - ✔✔Acetyl-CoA carboxylase
AND ANSWERS GUARANTEE A+
✔✔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? - ✔✔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? -
✔✔Cholesterol ester transfer protein (CETP)
✔✔Which of the following is a major source of extracellular cholesterol for human
tissues? - ✔✔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? - ✔✔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? - ✔✔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? -
✔✔Tetrahydrobiopterin (BH4)
✔✔A 17-year old female presents to her primary care and is diagnosed with a Vitamin
B12 (cobalamin) deficiency. In this individual, which of the following reactions would be
compromised? - ✔✔Conversion of methyl malonyl-Co A to succinyl-CoA
✔✔A 15-year-old female presents to her pediatrician with concerns over her inability to
sleep, increased feelings of depression and generalized fatigue. A full laboratory work-
up is ordered and based on these findings she is diagnosed with a melatonin deficiency.
Based on this information, metabolism of which of the following amino acids is likely
impaired? - ✔✔Tryptophan
✔✔A 52-year- old male sought medical help complaining about progressive appearance
of hyperchromic (hyper pigmented) papules on the edge of the second finger of both
hands. He also complained about darkening of urine. Incisional biopsy of one of the
spots on his hands and urine sample tested positive for or homogentisic acid. Based on
these findings a diagnosis of alkaptonuria is made. This diagnosis is consistent with a
deficiency in which of the following enzymes? - ✔✔Homogentisate oxidase
,✔✔Methotrexate is a potent anticancer agent that starves dividing cells of
deoxyribonucleotides through direct inhibition of which of the following processes? -
✔✔Metabolism of folic acid
✔✔A 47-year-old man complains of pain in the joints of his left big toe, which are
obviously swollen and tender. The pain has been chronic but became intolerable the
day after Thanksgiving when he had a large meal and several glasses of red wine.
Based on this information a diagnosis of gout is made. Which of the following is involved
in the pathophysiology of this patient's condition? - ✔✔Elevated uric acid
✔✔Which of the following is the common intermediate for purine synthesis? -
✔✔Inosine monophosphate
✔✔The ribonucleotide reductase is important for converting ribose bases to the deoxy
form. This conversion is coupled with the oxidation of which of the following
compounds? - ✔✔Thioredoxin
✔✔In pyrimidine synthesis, carbamoyl phosphate synthetase II (CPSII) can be
allosterically activated by which of the following compounds? - ✔✔5-phosphoribosyl 1-
pyrophosphate (PRPP)
✔✔Which of the following enzymes is used directly in the synthesis of dTMP
(thymidine)? - ✔✔Thymidylate synthase
✔✔The regulation of PRPP synthetase is critical in the production of both purines and
pyrimidines. This enzyme is inhibited under which of the following conditions? -
✔✔When both GDP and ADP are elevated
✔✔A 4-year-old girl presented to the clinic with megaloblastic anemia and failure to
thrive. Urinalysis showed significant sediment with extremely high levels of orotic acid. A
deficiency in which of the following enzymes would be consistent with this presentation?
- ✔✔Orotate phosphoribosyltransferase
✔✔The transamination of all amino acids requires which of the following cofactors? -
✔✔Pyridoxal phosphate (PLP)
✔✔Ubiquitination is a means of targeting a protein for which of the following cellular
processes? - ✔✔Proteasomal degradation
✔✔Which of the following reactions of the urea cycle takes place in the mitochondria? -
✔✔The synthesis of carbamoyl phosphate
, ✔✔Several amino acids are intermediates of the urea cycle, having side ammonia
groups that join with free carbon dioxide (CO2) and ammonia to produce net excretion
of ammonia as urea. Which of the following amino acids has a nitrogen in its side chain
and is an intermediate of the urea cycle? - ✔✔Arginine
✔✔Homocystinuria can be caused by several different enzyme or vitamin deficiencies.
An elevation of homocysteine and a decrease in cysteine would most likely present due
to which of the following deficiencies? - ✔✔Loss of function of cystathionine-β synthase
✔✔In an individual with a deficiency in the branched chain ketoacid dehydrogenase
complex, metabolism of which of the following amino acids would not likely be
impaired? - ✔✔Tyrosine
✔✔S-adenosylmethionine (SAM) is synthesized from ATP and methionine. A deficiency
in which of the following enzymes would impair the production of SAM? - ✔✔Methionine
adenosyltransferase (MAT)
✔✔The conversion of ribose bases into deoxy-bases will be occurring under which of
the following conditions? - ✔✔When cells are proliferating
✔✔A patient recently diagnosed with colon cancer is being treated with 5-fluorouracil.
Which of the following enzymes will this drug directly inhibit? - ✔✔Thymidylate synthase
✔✔An elevation of purine nucleotides will negatively regulate pyrimidine synthesis
through which of the following mechanisms? - ✔✔Inhibiting the activity of carbamoyl
phosphate synthetase II
✔✔Purine biosynthesis starts with the activation of a 5-carbon sugar. In this initial
reaction, ribose 5-phosphate is converted into which of the following compounds? -
✔✔PRPP (5- phosphoribosylpyrophosphate)
✔✔A 40-year-old male comes in to the doctor's office with severe pain in his big toe. He
is diagnosed with gout. Allopurinol is administered and this drug will inhibit which of the
following enzymes? - ✔✔Xanthine oxidase
✔✔In the salvage of purines, hypoxanthine-guanine phosphoribosyl transferase
(HGPRT) is responsible for which of the following processes? - ✔✔Conversion of
guanine to guanosine monophosphate (GMP)
✔✔In the case of a deficiency of biotin, which of the following enzymes required for fatty
acid metabolism will be impaired? - ✔✔Acetyl-CoA carboxylase
