UNE CHEM 1005 Mid term Study

UNE CHEM 1005 Midterm Study Guide Graded A+ What enzyme is used by the gluconeogenic pathway but NOT in the glycolytic pathway? ️Phosphoenolpyruvate Carboxykinase PEPCK Newborn screening results show a biotinidase deficiency in a 2 day old infant. The deficiency impairs the infant's ability to reuse and recycle biotin. Due to the enzymatic deficiency, the activity of what enzyme is likely impaired? ️Pyruvate carboxylase If unregulated, which of the following pairs of enzymes would represent a futile cycle? ️Fructose 1,6 bisphosphate and phosphofructokinase-1 When cortisol binds to its receptor, which of the following events occur top stimulate gluconeogenesis? ️Enhanced transcription of regulatory enzymes What compound allosterically activates pyruvate carboxylase ️Acetyl-CoA When the insulin to glucagon ratio is low, glycogenolysis is activated in the liver. Which of the following is primary fate of the glucose 6-phosphate released under these conditions? ️Dephosphorylated and released into the blood to maintain blood glucose What are the two major contributors to maintaining blood glucose levels during fasting? ️Hepatic glycogenolysis and gluconeogenesis Pyruvate dehydrogenase complex is highly regulated. The enzyme that will be most active when which of the following compounds is high? ️Pyruvate A deficiency in thiamine can reduce the activity of the pyruvate dehydrogenase complex. Under these conditions, you would expect a higher than normal blood concentration of which of the following metabolites? ️Pyruvate A-ketoglutarate dehydrogenase is the enzyme responsible for one of the irreversible reactions in the TCA cycle, What conversion does it catalyze? ️A-ketoglutarate to succinyl-CoA A 10-year old girl is swimming in a local competition. The intense exercise will increase intracellular calcium levels which in turn will increase flux thru the TCA cycle by stimulating the activity of all of the following enzymes EXCEPT ️Succinate Thiokinase TCA Cycle intermediates are always being removed for various reasons but the cycle does not run out of intermediates and stop. This is because the TCA cycle can replenish intermediates thru ️Using anaplerotic reactions A 10-year old boy is playing soccer and is sprinting after the ball. Under these anaerobic conditions, glucose oxidation primarily results in an increase in ️Lactate Which of the following best describes the net effect of the 8 steps of the TCA cycle? ️This process completely oxidizes an acetyl group to carbon dioxide Which of the following reactions is commonly used to replenish intermediates of the TCA cycle ️Glutamate to A-ketoglutarate Within the red blood cell, NADPH is used ️to re-reduce glutathione In the non-oxidative portion of the pentose phosphate pathway, 2-carbon fragments of keto-sugar can be transferred to other sugars to generate a larger sugar molecule. The reaction is catalyzed by which of the following enzymes? ️Transketolase Two primary products of the Pentose Phosphate Pathway ️Ribose-5-phosphate and NADPH The major regulatory step of the pentose phosphate pathway is catalyzed by ️Glucose 6-phosphate dehydrogenase Cofactor required for transketolase activity ️Thiamine diphosphate A deficiency in glucose-6-phosphate dehydrogenase reduces the levels of NADPH in the red blood cell. This leads to an increase in what compound? ️Oxidized Glutathione An 18-month old is diagnosed with hereditary fructose intolerance (deficiency of aldolase B). Lab testing showed low blood glucose levels at the time of presentation. This is likely due to the accumulation of fructose-1-phosphate and inhibition of what pathway? ️Gluconeogenesis and glycogenolysis Shortly after a meal there will be increased activity in which of the following pathways as a result of increased insulin? ️Glycolysis A novel signaling cascade is discovered that you suspect activates G-As subunits. What downstream event would be consistent with this discovery? ️Activation of adenylyl cyclase A young woman goes to work without eating breakfast and lunch. What pathway is providing substrates used to generate ATP in the liver? ️Free Fatty Acids What is the primary oxidized fuel for skeletal muscle in the fasted state? ️Free Fatty Acids A teenage female presenting with lack of menstration (amenorhea) is found to have a dysfunctional steroid receptor characteristic of androgen insensitivity syndrome. What accurately describes steroid hormones? ️They enhance transcription when bound to receptors Steroid hormones bind what type of receptor? ️Intracellular receptors Which of the following statements is consistent with the actions of epinephrine? ️Enhances glucose