UNE Biochemistry Final Test Questions with Correct Solutions, Rated A+

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