Amino acid metabolism-Multiple choice questions (set-1)

Q.1- A 12 -year-old boy develops convulsions. After running an Electroencephalogram(EEG), a neurologist determines that the child has epilepsy. He is started on benzodiazepine which promotes the activity of GABA. GABA is derived from Glutamate by which of the following reactions?

a) Transamination

b) Decarboxylation

c) Deamination

d) Hydroxylation

e) Dehydrogenation

Q.2- A couple of African- American descent gives birth to a boy after an otherwise uneventful pregnancy. The child is exceptionally fair-skinned and has almost white hair. Further examination reveals red pupils.  A postnatal screen is likely to confirm the deficiency of which of the following enzymes?

a) Glutathione reductase

b) Glutathione peroxidase

c) Tyrosinase

d) Methionine synthase

e) Cystathionine beta-synthase

Q.3- A 16- year -old girl is found by her parents unconscious on the bathroom floor with an empty bottle of acetaminophen in the toilet. She is rushed to the hospital where she is given several doses of N-acetyl Cysteine. Acetaminophen overdose is potentially life-threatening because it depletes the cellular stores of Glutathione. Which of the following amino acid is another component of Glutathione besides Cysteine and Glutamic acid?

a) Methionine

b) Arginine

c) Lysine

d) Ornithine

e) Glycine

Q.4-  A 56-year-old man with long-standing poorly controlled diabetes mellitus visits his primary care physician for a follow-up after a recent hospitalization. The patient experienced an episode of acute renal failure while in hospital, and his serum creatinine rose to 2.4 mg/dl ( Normal, 0.7- 1.5 mg/dl). Creatinine a marker of kidney function is derived from which of the following precursors?

a) Arginine, Lysine, and Glutamine

b) Glutamic acid, Cysteine, and Glycine

c) Methionine, Serine, and Glycine

d) Methionine, Arginine, and Glycine

e) Cysteine, Glycine, and Arginine.

Q.5- S- Adenosyl  Methionine (Active Methionine) is required for the synthesis of which of the following compounds?

a) Thyroid hormone

b) Melanin

c) Epinephrine

d) Serotonin

e) Bile salts.

Q.6- Which of the following compounds is formed from hydroxylation requiring vitamin C and subsequent methylation?

a) Histamine

b) Dopamine

c) Epinephrine

d) Creatine

e) Melanin

Q.7- A 40-year old woman complains of decreased energy, significant weight gain, and cold intolerance. She is seen by her family physician, who has diagnosed her to be having hypothyroidism (Low level of thyroid hormone). Which of the following is a precursor for thyroid hormone?

a) DOPA

b) Glutamine

c) Tyrosine

d)Tryptophan

e) Threonine.

Q.8- A 63 -year old woman reports a long history of joint pain. Her fingers are severely deformed secondary to rheumatoid arthritis. Upon visiting a rheumatologist, she is started on methotrexate. This drug inhibits which of the following conversions?

a) Dopamine to norepinephrine conversion

b) Tyrosine to Dopa

c) Dihydrofolate to Tetra hydro folate

d) Phenyl Alanine to Tyrosine

e) N-Acetyl serotonin to melatonin

Q.9-  A 59-year-old woman develops a shuffling gait and a pin- rolling tremor. She is referred to a neurologist for evaluation. After a thorough workup, a diagnosis of Parkinson’s disease is made and the patient is placed on Monoamine oxidase inhibitor. The drug, in this case, is given to decrease the degradation of which of the following?

a) Serotonin

b) Dopamine

c) Nicotinamide

d) Melatonin

e) Nitric oxide

Q.10- During a medical rotation, a medical student volunteered for a respiratory physiology examination that determines basal metabolic rate and the respiratory quotient. She followed the protocol for a resting individual in the post-absorptive state. Which of the following amino acids would be found in the highest concentration in the serum?

a) Alanine and Glutamine

b) Arginine and Ornithine

c) Glutamate and Aspartate

d) Branched-chain amino acids

e) Hydrophobic amino acids

Q.11-A 27- year-old semiprofessional tennis player seeks advice from a hospital-based nutritionist concerning his diet supplements. His coach had given him amino acid supplements consisting of phenylalanine and tyrosine. The rationale was that these precursors to several neurotransmitters will “help his brain focus” on his game. In reality, the excess amino acids are used for energy, with a poor and eclectic diet. Phenyl Alanine upon metabolism, enter the TCA cycle as which of the following?

a) Oxaloacetate

b) Citrate

c) Succinyl CoA

d) Fumarate

e) α- Ketoglutarate

Q.12- In a 39-year-old woman who just gave birth, chorionic villus sampling was performed, and a battery of genetic panels was assessed on the newborn. One marker indicated a defective Cystathionine -β- Synthase. Which of the following compounds you most likely expect to be elevated in the blood of the infant at birth if the mother was not treated properly?

a) Valine

b) Methionine

c) Threonine

d) Glutamine

e) Cysteine

Q.13- A 55-year-old man suffers from cirrhosis of the liver. Toxins such as ammonia are not properly metabolized by the liver and can damage the brain. Which of the following compounds is expected to be in the highest concentration in the brain  as a result of the detoxification of ammonia?

a) Alpha-ketoglutarate

b) Glutamate

c) Glutamine

d) GABA

e) Asparagine

Q.14- Which of the following enzymes requires adenosine triphosphate (ATP) to mediate its reactions?

a) Arginino succinate lyase

b) Argininosuccinate synthetase

c) Arginase

d) Glutaminase

e) Ornithine transcarbamoylase

Q.15- Which of the following amino acids is not converted to Acetyl CoA upon metabolism?

a) Tyrosine

b) Leucine

c) Tryptophan

d) Lysine

e) Valine

Key to Answers-

1)-b,      

2)-c,     

3)-e,      

4)- d,     

5)- c,     

6)-c,              

7)-c,      

8)-c,      

9)-b,     

10)-a,   

11)- d,              

12-b,   

13)-C

14)-b,   

15)-e