UNE Biochemistry Final Questions With 100% Correct Answers.

UNE Biochemistry Final Questions With 100% Correct Answers. 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? Alanine Which of the following enzymes is correctly paired with its activator? N-acetylglutamate synthatase; arginine The urea cycle takes place in which of the following subcellular locations? the cytosol and the mitochondria Which of the following enzymes is regulated by N-acetylglutamate (NAGs)? CPS I Which of the following enzymes is the regulatory step in the urea cycle? Carbamoyl phosphate synthetase I (CPS I) Which of the following statements is consistent with nitrogen transport in the fasted state? 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? 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? 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? Increases degradation of HMG-CoA reductase Dietary cholesterol is primarily transported in the body by which of the following lipoproteins? 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? 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? Decreasing hepatic cholesterol biosynthesis A deficiency in the LDL receptor will result in an initial decrease in which of the following? 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? 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? 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? 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? 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 During fatty acid synthesis, after the initial step involving acetyl-CoA, the fatty acid chain is elongated by the addition of which of the following compounds? Malonyl-CoA Which of the following compounds or substrates is required for the synthesis of tyrosine? (+ indicates the compound is required; - indicates the compound is not required) 4 A 2-day-old infant test positive for hyperphenylalaninemia. This is most likely caused by a heritable defect in which of the following enzymes? Phenylalanine hydroxylase You and a friend are being chased by a bear. Under these conditions levels of epinephrine are increased due to metabolism of which of the following amino acids? Tyrosine In pyrimidine synthesis, uridine triphosphate (UTP) can feedback and inhibit which of the following enzymes? Carbamoyl phosphate synthase II Which of the following characteristics distinguish most RNA molecules from DNA? Uridine base on RNA, whereas a thymidine base on DNA Which of the following lipoproteins distributes dietary lipids? Chylomicron The interaction fo chylomicrons with lipoprotein lipase is stimulated by which of the following App proteins? ApoCII Nascent chylomicrons are synthesized in which tissue? Intestine Bile salts are synthesized from cholesterol and are used for the emulsification of dietary lipids. What is the primary fate of bile salts during digestion? They are reabsorbed in the ileum Nascent chylomicrons interact with HDL particles and obtain which fo the following Apo proteins? ApoCII and ApoE The activity of pancreatic lipase is inhibited by which of the following compounds? Bile salts Which fo the following statements regarding liid digestion and absorption is true? A. The products of lipid digestion travel in the circulatory system in the form of micelles. B. The products of lipid digestion diffuse into capillaries in the vicinity of the intestinal epithelium. C. Pancreatic lipase emulsifies lipids. D. The products of lipid digestion are resynthesizes into triacylglycerols in the intestinal epithelial cells. e. In the absence of bile salts, no digestion of lipids would occur. The products of lipid digestion are resynthesizes into triacylglycerols in intestinal epithelial cells. Under fasting conditions, elevated glucagon will activate which of the following enzymes?