Chapter 18: Amino Acid Oxidation Ad The Production Of Urea
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- 1.Which of these is not a protease that acts in the small intestine?
- A.
Chymotrypsin
- B.
Elastase
- C.
Enteropeptidase
- D.
Secretin
- E.
Trypsin
- 2.In the digestion of protein that occurs in the small intestine, which enzyme is critical in the activation of zymogens?
- A.
Enteropeptidase
- B.
Hexokinase
- C.
Papain
- D.
Pepsin
- E.
Secretin
- 3.Which of the following is a zymogen that can be converted to an endopeptidase that hydrolyzes peptide bonds adjacent to Lys and Arg residues?
- A.
Chymotrypsinogen
- B.
Pepsin
- C.
Pepsinogen
- D.
Trypsin
- E.
Trypsinogen
- 4.In amino acid catabolism, the first reaction for many amino acids is a(n):
- A.
Decarboxylation requiring thiamine pyrophosphate (TPP).
- B.
Hydroxylation requiring NADPH and O2.
- C.
Oxidative deamination requiring NAD+.
- D.
Reduction requiring pyridoxal phosphate (PLP).
- E.
Transamination requiring pyridoxal phosphate (PLP).
- 5.The coenzyme required for all transaminations is derived from:
- A.
Niacin.
- B.
Pyridoxine (vitamin B6).
- C.
Riboflavin.
- D.
Thiamin.
- E.
Vitamin B12.
- 6.The coenzyme involved in a transaminase reaction is:
- A.
Biotin phosphate.
- B.
Lipoic acid.
- C.
Nicotinamide adenine dinucleotide phosphate (NADP+).
- D.
Pyridoxal phosphate (PLP).
- E.
Thiamine pyrophosphate (TPP).
- 7.Transamination from alanine to alpha-ketoglutarate requires the coenzyme:
- A.
Biotin.
- B.
NADH.
- C.
No coenzyme is involved.
- D.
Pyridoxal phosphate (PLP).
- E.
Thiamine pyrophosphate (TPP).
- 8.Pyridoxal phosphate is a cofactor in this class of reactions:
- A.
Acetylation.
- B.
Desulfuration.
- C.
Methylation.
- D.
Reduction.
- E.
Transamination.
- 9.Which of the following is not true of the reaction catalyzed by glutamate dehydrogenase?
- A.
It is similar to transamination in that it involves the coenzyme pyridoxal phosphate (PLP).
- B.
NH4+ is produced.
- C.
The enzyme can use either NAD+ or NADP+ as a cofactor.
- D.
The enzyme is glutamate-specific, but the reaction is involved in oxidizing other amino acids.
- E.
Alpha-Ketoglutarate is produced from an amino acid.
- 10.Glutamate is metabolically converted to alpha-ketoglutarate and NH4+ by a process described as:
- A.
Deamination.
- B.
Hydrolysis.
- C.
Oxidative deamination.
- D.
Reductive deamination.
- E.
Transamination.
- 11.The conversion of glutamate to an alpha-ketoacid and NH4+:
- A.
Does not require any cofactors.
- B.
Is a reductive deamination.
- C.
Is accompanied by ATP hydrolysis catalyzed by the same enzyme.
- D.
Is catalyzed by glutamate dehydrogenase.
- E.
Requires ATP.
- 12.Which of the following conversions require more than one step? 1. Alanine --> pyruvate 2. Aspartate --> oxaloacetate 3. Glutamate --> ketoglutarate 4. Phenylalanine --> hydroxyphenylpyruvate 5. Proline --> glutamate
- A.
1 and 4
- B.
1, 2 and 4
- C.
1, 3 and 5
- D.
2, 4 and 5
- E.
4 and 5
- 13.Urea synthesis in mammals takes place primarily in tissues of the:
- A.
Brain.
- B.
Kidney.
- C.
Liver.
- D.
Skeletal muscle.
- E.
Small intestine.
- 14.Which substance is not involved in the production of urea from NH4+ via the urea cycle?
- A.
Aspartate
- B.
ATP
- C.
Carbamoyl phosphate
- D.
Malate
- E.
Ornithine
- 15.Which of these directly donates a nitrogen atom for the formation of urea during the urea cycle?
- A.
Adenine
- B.
Aspartate
- C.
Creatinine
- D.
Glutamate
- E.
Ornithine
- 16.Conversion of ornithine to citrulline is a step in the synthesis of:
- A.
Aspartate.
- B.
Carnitine.
- C.
Pyruvate.
- D.
Tyrosine.
- E.
Urea.
- 17.In the urea cycle, ornithine transcarbamoylase catalyzes:
- A.
Cleavage of urea to ammonia.
- B.
Formation of citrulline from ornithine and another reactant.
- C.
Formation of ornithine from citrulline and another reactant.
- D.
Formation of urea from arginine.
- E.
Transamination of arginine.
- 18.
- A.
Krebs was a major contributor to the elucidation of the pathway involved.
- B.
The amino acid arginine is the immediate precursor to urea.
- C.
The carbon atom of urea is derived from mitochondrial HCO3–.
- D.
The precursor to one of the nitrogens of urea is aspartate.
- E.
The process of urea production is an energy-yielding series of reactions.
- 19.Which of the following amino acids are essential for humans?
- A.
Alanine
- B.
Aspartic acid
- C.
Asparagine
- D.
Serine
- E.
Threonine
- 20.If a person's urine contains unusually high concentrations of urea, which one of the following diets has he or she probably been eating recently?
- A.
High carbohydrate, very low protein
- B.
Very high carbohydrate, no protein, no fat
- C.
Very very high fat, high carbohydrate, no protein
- D.
Very high fat, very low protein
- E.
Very low carbohydrate, very high protein
- 21.Which of these amino acids can be directly converted into a citric acid cycle intermediate by transamination?
- A.
Glutamic acid
- B.
Serine
- C.
Threonine
- D.
Tyrosine
- E.
Proline
- 22.Which of these amino acids are both ketogenic and glucogenic? 1. Isoleucine 2. Valine 3. Histidine 4. Arginine 5. Tyrosine
- A.
1 and 5
- B.
1, 3, and 5
- C.
2 and 4
- D.
2, 3, and 4
- E.
2, 4, and 5
- 23.Tetrahydrofolate (THF) and its derivatives shuttle ______________ between different substrates.
- A.
Electrons
- B.
H+
- C.
Acyl groups
- D.
One carbon units
- E.
NH2 groups
- 24.The amino acids serine, alanine, and cysteine can be catabolized to yield:
- A.
Fumarate.
- B.
Pyruvate.
- C.
Succinate.
- D.
Alpha-ketoglutarate.
- E.
None of the above.
- 25.Serine or cysteine may enter the citric acid cycle as acetyl-CoA after conversion to:
- A.
Oxaloacetate.
- B.
Propionate.
- C.
Pyruvate.
- D.
Succinate.
- E.
Succinyl-CoA
- 26.The human genetic disease phenylketonuria (PKU) can result from:
- A.
Deficiency of protein in the diet.
- B.
Inability to catabolize ketone bodies.
- C.
Inability to convert phenylalanine to tyrosine.
- D.
Inability to synthesize phenylalanine.
- E.
Production of enzymes containing no phenylalanine.
- 27.In the human genetic disease maple syrup urine disease, the metabolic defect involves:
- A.
A deficiency of the vitamin niacin.
- B.
Oxidative decarboxylation.
- C.
Synthesis of branched chain amino acids.
- D.
Transamination of an amino acid.
- E.
Uptake of branched chain amino acids into liver.
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