SCI 260 Stratford University Amino Acids & Metabolism Biochemistry Paper

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Science

SCI 260

Stratford University

SCI

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  • Which one of the following statements about amino acids and their metabolism is correct;
  • Free amino acids are taken into the enterocytes by a proton-linked transport system
  • Liver uses ammonia to buffer protons
  • Muscle-derived glutamine is metabolized in liver and kidney tissue to ammonia plus α – ketoglutarate
  • The toxic ammonia generated from the amide nitrogen of amino acids is transported through blood as arginine

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Introduction to Biochemistry (SCI 260) Final Exam Quarter 3, 2020 Instructor’s name: Mustafa Qasim Student’s Name: 1. Which one of the following statements about amino acids and their metabolism is correct; a. Free amino acids are taken into the enterocytes by a proton-linked transport system b. Liver uses ammonia to buffer protons c. Muscle-derived glutamine is metabolized in liver and kidney tissue to ammonia plus α – ketoglutarate d. The toxic ammonia generated from the amide nitrogen of amino acids is transported through blood as arginine 2. The second amino group of urea is derived from; a. Glutamate b. Aspartate c. Arginine d. Free ammonia transported to the liver 3. The rate limiting step of the urea cycle is; a. The first step which occurs in the mitochondria and requires the presence of Nacetylglutamate as a cofactor b. The last step driven by arginase enzyme c. The first two steps since it depends on the mitochondrial activity of the cell d. The third step since it’s a step in the middle of the cycle and requires argininosuccinate synthetase 4. A female neonate did well until approximately age 24 hours, when she became lethargic. A sepsis workup proved negative. At 56 hours, she started showing focal seizure activity. The plasma ammonia level was found to be 887 µmol/l (normal 5–35 µmol/l). Quantitative plasma amino acid levels revealed a marked elevation of citrulline but not argininosuccinate. Which one of the following enzymic activities is most likely to be deficient in this patient; a. Arginase b. Argininosuccinate lyase c. Argininosuccinate synthetase d. Carbamoyl phosphate synthetase I Questions 17 – 20 Please read carefully the following case study and provide a suitable answer to its questions. (This is a modified case study of the one retrieved from https://www.chem.uwec.edu) A male baby born after a normal pregnancy appeared to be healthy until after the third day after his birth. He became lethargic, hypnotic (low muscle tone), his breathing was shallow and lead to apnea. First, he was hooked up to a mechanical respirator. A blood sample was taken to the lab and found that his plasma ammonia level was 474 µmol/L. As a healthcare provider, you have put the baby under peritoneal dialysis until results of plasma amino acid levels and urine organic acid tests are ordered. The baby went into a deep coma. The lab tests revealed the following; Plasma ammonia 474 µmol/L Plasma glutamine 1560 µmol/L (normal value 350 – 700 µmol/L) Plasma arginine Low Plasma N-acetylglutamine (NAG) High Plasma carbamoyl phosphate High Plasma PH level 7.9 Based on the above lab result; 5. What is your diagnosis of this case? Provide a suitable reason to your answer along with the specific reaction (equation) of urea cycle on which you are referring to on your answer. 6. Why the patient has high blood level of glutamine? 7. Why the patient has high plasma level of NAG? 8. How can you treat this condition and save the baby from a life-threatening coma? 9. What type of condition is this? (Congenital or Acquired) 10. Proteasome is a protein complex responsible of; a. Activating ubiquitin b. Degrading target proteins c. Autophagy d. Deubiquitination 11. At low temperatures, the rate of enzyme reactions become slower due to; a. Enzyme inhibition b. The enzyme will not bind to substrate due to denaturation c. Substrate will collide less with enzyme molecules d. The enzyme will not be synthesized 12. A protein has a short half-life (rapidly degraded) if it contains which of the following; a. Globular structure b. Serine at its N-terminus c. PEST amino acids d. COAL amino acid transporter system 13. While studying a metabolic reaction, you noticed the enzyme on the experiment has high affinity to its substrate molecules. What expression best fits your observation; a. High Vmax b. High Km c. Low Km d. High Ka and Low PH 14. In the UPS, tagged proteins in the cell will have; a. E1 attached to them b. Monoubiquitin tagged for degradation c. E3 conjugated protein d. Polyubiquitin chain 15. In lysosome degradation system, organelles are degraded through autophagy by; a. Acid hydrolase b. Pepsin c. Amylase d. Carboxypeptidase 16. Anticipate what happens when the proteasome system is defective/ nonfunctional? e. Cell death f. Accumulation of toxic protein g. Nonselective degradation h. Need more information 17. Which of the following enzymes is targeted by cholesterol synthesis inhibitors; a. Acetylcholine esterase b. Tyrosine kinase c. Ribonuclease d. HMG-Co A reductase 18. What group of medications can be used to inhibit the enzyme on the previous question? a. NSAIDs b. ACEIs c. ARBs d. Statins 19. The first amino group of urea is derived from; e. Glutamate f. Aspartate g. Arginine h. Free ammonia transported to the liver 20. Which step/steps of the urea cycle occur in the mitochondria; e. The first step which occurs in the mitochondria and requires the presence of Nacetylglutamate as a cofactor f. The last step driven by arginase enzyme g. The first two steps since it depends on the mitochondrial activity of the cell h. The third step since it’s a step in the middle of the cycle and requires argininosuccinate synthetase 21. Which of the following details the correct order in which proteins are digested? a. Pepsin breaks down peptide bonds in the stomach, then the pancreatic enzymes complete the digestion in the intestines. b. The pancreatic enzymes break down peptide bonds in the stomach, then chymotrypsin completes the digestion in the liver. c. Carboxypeptidase breaks down peptide bonds in the stomach, then the pancreatic enzymes complete the digestion in the intestines. d. Trypsin breaks down peptide bonds in the stomach, then chymotrypsin completes the digestion in the liver. 22. What is the coenzyme in transamination reactions? a. Vit C b. Vit D c. Vit B6 d. Vit B12 In the transamination reaction shown to the right, which of the following are the products X and Y; 23. What is X; a. Alanine b. Asparate c. Glutamate d. α-ketoglutarate 24. What is Y; a. Alanine b. Asparate c. Glutamate d. α-ketoglutarate 25. A 27 years old male athlete became lethargic after a severe workout. He was also experiencing cold sweat and a mild fever. A sepsis workup proved negative. At 24 hours, he started showing focal seizure activity. A statement made by his brother “He is following a high protein diet for body building and, in the past 24 hours, he drunk nothing but protein and amino acid shakes”. The plasma ammonia level was found to be 887 µmol/l (normal 5–35 µmol/l). Quantitative plasma amino acid levels revealed a marked elevation of acetylCoA, arginine, glutamine and aspartate. What is your diagnosis of this case and can you provide a suitable treatment?!
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Introduction to Biochemistry (SCI 260)
Final Exam
Quarter 3, 2020

Instructor’s name: Mustafa Qasim
Student’s Name:

1. Which one of the following statements about amino acids and their metabolism is correct;
a. Free amino acids are taken into the enterocytes by a proton-linked transport system
b. Liver uses ammonia to buffer protons
c. Muscle-derived glutamine is metabolized in liver and kidney tissue to ammonia plus α –
ketoglutarate
d. The toxic ammonia generated from the amide nitrogen of amino acids is transported
through blood as arginine
2. The second amino group of urea is derived from;
a. Glutamate
b. Aspartate
c. Arginine
d. Free ammonia transported to the liver
3. The rate limiting step of the urea cycle is;
a. The first step which occurs in the mitochondria and requires the presence of Nacetylglutamate as a cofactor
b. The last step driven by arginase enzyme
c. The first two steps since it depends on the mitochondrial activity of the cell
d. The third step since it’s a step in the middle of the cycle and requires argininosuccinate
synthetase
4. A female neonate did well until approximately age 24 hours, when she became lethargic. A
sepsis workup proved negative. At 56 hours, she started showing focal seizure activity. The
plasma ammonia level was found to be 887 µmol/l (normal 5–35 µmol/l). Quantitative plasma
amino acid levels revealed a marked elevation of citrulline but not argininosuccinate. Which one
of the following enzymic activ...


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