Metabolism and Glycolysis, Exams of Nursing

Download Metabolism and Glycolysis and more Exams Nursing in PDF only on Docsity! BCH 4024 Exam 3 Metabolism - correct answer ✔✔overall processes in which living systems acquire and 2 utilize free energy to carry out life functions. Reactions that form or break CC bond - correct answer ✔✔Aldol Claisen Ester Decarboxylation -NFE - correct answer ✔✔equation in order to find ΔG when given an equation ATP hydrolysis drives metabolism by - correct answer ✔✔shifting the equilibrium of coupled reactions Hydrolysis of ATP to ADP and Pi to energize endergonic physiological processes. - correct answer ✔✔Such as Protein folding and Muscle contractions Formation of ATP - correct answer ✔✔-Substrate-level phosphorylation -Adenylate kinase reaction -Oxidative phosphorylation and Photophosphorylation substrate-level phosphorylation - correct answer ✔✔ATP formed by direct transfer of a phosphoryl group from a "high-energy" compound to ADP. adenylate kinase reaction - correct answer ✔✔-AMP resulting from pyrophosphate cleavage reaction of ATP is converted to ADP in a reaction catalyzed by the enzyme adenylate kinase -the ADP produced is then converted to ATP through substrate level phosphorylation or oxidative phosphorylation oxidative phosphorylation - correct answer ✔✔Part of the electron transport chain. A process occurring in the mitochondria that results in the formation of ATP from the flow of electrons across the inner membrane to bind with oxygen. Phosphocreatine - correct answer ✔✔Readily available pool of high-energy phosphate bonds for ATP formation RBCs - correct answer ✔✔Depend entirely on glycolysis Kinase - correct answer ✔✔an enzyme that catalyzes the transfer of a phosphate group from ATP to a specified molecule. hexokinase/glucokinase - correct answer ✔✔Glucose is captured within the cell when it is phosphorylated. Important so there is no way for glucose to leave the cell once converted to G-6-P; Also the phosphorylation group imparts energy Induced fit catalysis - correct answer ✔✔Open = no substrate Closed = With Phosphohexose isomerase - correct answer ✔✔G-6-P to F-6-P Phosphofructokinase-1 (PFK-1) - correct answer ✔✔RATE LIMITING STEP First committed step of glycolysis Aldolase - correct answer ✔✔cleaves fructose 1,6-bisphosphate Type VIII glycogen storage disease is one of the glycogen storage diseases. In this disease the enzyme, phosphorylase b kinase, is nonfunctional. The result of this would lead to which of the following in liver cells? - correct answer ✔✔Failure of liver cells to breakdown glycogen in response to glucagon during fasting A patient recovering from an operation that is on intravenous fluids develops mouth lesions. An analysis of the urine is done revealing very low levels of riboflavin. Recall that riboflavin is Vitamin B2 and is the precursor for flavin adenine dinucleotide (FAD). Which of the citric acid cycle enzymes would be most affected by this deficiency? - correct answer ✔✔Succinate dehydrogenase In the figure below is a representation of an experimental system. In this system, a membrane vesicle has been constructed with the following components (NOT ALL COMPONENTS ARE SHOWN IN THE FIGURE): Complex I, Complex III, Complex IV, ubiquinone (Coenzyme Q), and cytochrome c of the electron transport chain, ATP synthase, ADP, Pi, Coenzyme Q, and Protein X If protein X is a light-driven proton pump that when illuminated pumps protons from outside the vesicle to inside the vesicle, what would be the minimal components necessary for the synthesis of ATP if the system was illuminated by light? - correct answer ✔✔Protein X, ADP, Pi, and ATP synthase In liver, what two metabolic pathways would be activated during fasting? (i.e., High glucagon/insulin ratio) - correct answer ✔✔Glycogenolysis (glycogen breakdown) and gluconeogenesis One of the clinical cases presented was of acute alcohol poisoning. In that case an individual was found unconscious after a period of heavy drinking. The following series of reactions was described in which ethanol is oxidized to acetaldehyde followed by oxidation of acetaldehyde to acetate that can be further converted to acetyl-CoA. Notice both steps are oxidation reactions in which electrons are transferred from ethanol and acetaldehyde to NAD+ as the electron acceptor. Ingestion of high levels of ethanol results in the production of high levels of NADH. Why does this lead to unconsciousness and coma? - correct answer ✔✔High levels of NADH leads to the inhibition the pyruvate dehydrogenase complex, isocitrate dehydrogenase and α-ketoglutarate dehydrogenase complex. A recent paper in the journal Nature describes a discovery in which high levels of UDP-glucose were found to prevent the conversion of an epithelial cell to a mesenchymal cell thus preventing what is known as the epithelial mesenchymal transition or EMT. EMT is an important step in which a tumor cell is converted to a mobile, invasive or metastatic cancer cell. In what metabolic pathway that we talked about is UDP-glucose used as a substrate? - correct answer ✔✔Glycogen synthesis An individual that becomes a chronic user of alcohol is said to "drink his lunch"; meaning that instead of a regular intake of solid, nutritious food he consumes ethanol. Of the coenzymes we discussed, Vitamin B1 (thiamine pyrophosphate, TPP) is often missing from the diets of chronic alcohol abusers. In what enzyme(s) or enzyme complexes is thiamine pyrophosphate a necessary component? - correct answer ✔✔α-ketoglutarate dehydrogenase and pyruvate dehydrogenase complex An uncommon genetic mutation in the human population is in the gene that codes for glucose 6- dehydrogenase, the enzyme that catalyzes the first and rate-limiting step of the pentose phosphate pathway. Individuals that inherit this mutation are often protected against developing malaria. This is because they are unable to effectively remove reactive oxygen species (ROS, i.e., superoxide radical, hydrogen peroxide, and hydroxyl radical) and thus the protozoan (Plasmodium falciparum), which infects red blood cells causing malaria, is destroyed by ROS. Why would a mutation causing a defective or inactive glucose 6-dehydrogenase protect these individuals from malaria? - correct answer ✔✔Lack of sufficient levels of NADPH allows for high levels of ROS which kills the malarial parasite. In the liver, a product of the pentose phosphate pathway, xylulose 5- phosphate, is an activator of a protein phosphatase that has as a target, the bifunctional enzyme. When the liver cell is conserving carbohydrate, in the form of fatty acids, and when glucose levels are high, the pentose phosphate pathway is activated to produce sufficient levels of NADPH for fatty acid biosynthesis. Why is the bifunctional enzyme dephosphorylated? - correct answer ✔✔Activation of the kinase activity of the bifunctional enzyme results in an increase in fructose 2,6-bisphosphate and, therefore, an increase in glycolysis which supplies acetyl-CoA for fatty acid synthesis. The complete oxidation of one mole of pyruvate to CO2 proceeds with an overall production of 12.5 moles of ATP or its equivalent. Which one of the following compounds DOES NOT contribute to the production of these ATP equivalents? - correct answer ✔✔NADPH All of the oxidative steps from pyruvate through the citric acid cycle are linked to the reduction of NAD+ except the reaction catalyzed by - correct answer ✔✔succinate dehydrogenase Which of the following enzymes is paired with an effector which results in an INCREASE in the activity of the enzyme? - correct answer ✔✔Acetyl-CoA carboxylase And Citrate When blood glucose levels are low, which of the following is FALSE? - correct answer ✔✔Carnitine acyltransferase I - phosphorylated and inhibited When blood glucose levels are low, Acetyl-CoA carboxylase is - correct answer ✔✔phosphorylated and inhibited When blood glucose levels are low, Hormone-sensitive lipase Is - correct answer ✔✔phosphorylated and activated When blood glucose levels are low, Fatty acid synthase Is - correct answer ✔✔not regulated by glucose levels Fatty acid synthase catalyzes the synthesis of the 16-carbon saturated fatty acid, palmitate. In the endoplasmic reticulum there are fatty acid elongases; enzymes that catalyze the addition of two additional carbons originating from malonyl-CoA to form the 18-carbon saturated fatty acid, stearate. The elongases use a similar mechanism as the fatty acid synthase but the reaction begins with the condensation of palmitoyl-CoA with malonyl-CoA (Reaction step 1 in the figure below). What would be the reactions of step 2, 3 and 4 if the reaction mechanism is similar to that of fatty acid synthase? - correct answer ✔✔2. Reduction, 3. Dehydration, 4. Reduction Recently a new mutation in the gene for Acetyl-CoA Carboxylase (ACC) was discovered in which the critical serine residue of the enzyme was mutated to an alanine residue thus preventing the enzyme from being phosphorylated. What would be the consequences to a liver cell with this mutation? - correct answer ✔✔Fatty acid β-oxidation would be inhibited due to elevated levels of malonyl-CoA. Which one of the following is NOT an intermediate in the synthesis of cholesterol from acetyl-CoA? - correct answer ✔✔Malonyl-CoA patient presents to your clinic with hypercholesterolemia (Blood LDL levels greater than 200 mg/dL). You take their medical history and recognize that they do not have lifestyle indicators for high cholesterol (i.e., high fat diet, lack of exercise, overweight). This leads you to think this person may have an inherited condition. What is the most likely cause of this person's high cholesterol? - correct answer ✔✔This person has a genetic mutation that results in a defect in the LDL receptor which leads to a failure of LDL to be taken up by receptor- mediated endocytosis. Acetyl-CoA is required as allosteric activator. Acetyl CoA (ACA) - correct answer ✔✔Measures the energy status of the cell high ACA = Sufficient energy for glucose synthesis Phosphoenolpyruvate carboxykinase (PEPCK) - correct answer ✔✔Cytosolic and mitochondria isozymes. Requires GTP as energy source. Substrate is oxaloacetate. Product is phosphoenolpyruvate (PEP). Hexokinase - correct answer ✔✔High affinity, K m = 0.2 mM Low capacity Product inhibited (G6-P) Glucokinase - correct answer ✔✔Liver only Low affinity, K m= 10 mM High capacity Not inhibited by product (G6-P) Phosphofructokinase-1 - correct answer ¥ ¥ Regulated