UNE Biochemistry Final Questions With Solutions
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 Ans -
Alanine
Which of the following enzymes is correctly paired with its activator?
Correct Ans - N-acetylglutamate synthatase; arginine
The urea cycle takes place in which of the following subcellular locations?
Correct Ans - the cytosol and the mitochondria
Which of the following enzymes is regulated by N-acetylglutamate (NAGs)?
Correct Ans - CPS I
Which of the following enzymes is the regulatory step in the urea cycle?
Correct Ans - Carbamoyl phosphate synthetase I (CPS I)
Which of the following statements is consistent with nitrogen transport in
the fasted state? Correct Ans - 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
Ans - 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 Ans -
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 Ans - Increases degradation of HMG-CoA reductase
Dietary cholesterol is primarily transported in the body by which of the
following lipoproteins? Correct Ans - 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 Ans - 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 Ans -
Decreasing hepatic cholesterol biosynthesis
A deficiency in the LDL receptor will result in an initial decrease in which
of the following? Correct Ans - 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
Ans - 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 Ans -
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 Ans - 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 Ans - 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 Ans - Cholesterol ester transfer protein (CETP)
, Which of the following is a major source of extracellular cholesterol for
human tissues? Correct Ans - 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 Ans - 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 Ans
- 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 Ans - 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? Correct Ans -
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?
Correct Ans - 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? Correct Ans - Homogentisate
oxidase
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 Ans -
Alanine
Which of the following enzymes is correctly paired with its activator?
Correct Ans - N-acetylglutamate synthatase; arginine
The urea cycle takes place in which of the following subcellular locations?
Correct Ans - the cytosol and the mitochondria
Which of the following enzymes is regulated by N-acetylglutamate (NAGs)?
Correct Ans - CPS I
Which of the following enzymes is the regulatory step in the urea cycle?
Correct Ans - Carbamoyl phosphate synthetase I (CPS I)
Which of the following statements is consistent with nitrogen transport in
the fasted state? Correct Ans - 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
Ans - 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 Ans -
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 Ans - Increases degradation of HMG-CoA reductase
Dietary cholesterol is primarily transported in the body by which of the
following lipoproteins? Correct Ans - 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 Ans - 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 Ans -
Decreasing hepatic cholesterol biosynthesis
A deficiency in the LDL receptor will result in an initial decrease in which
of the following? Correct Ans - 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
Ans - 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 Ans -
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 Ans - 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 Ans - 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 Ans - Cholesterol ester transfer protein (CETP)
, Which of the following is a major source of extracellular cholesterol for
human tissues? Correct Ans - 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 Ans - 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 Ans
- 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 Ans - 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? Correct Ans -
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?
Correct Ans - 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? Correct Ans - Homogentisate
oxidase
