UNE BIOCHEMISTRY MIDTERM STUDY BANK WITH 100% CORRECT ANSWERS

Succinate is a substrate for which complex in the electron transport chain? a.) Complex 1 (NADH-1 oxidoreductase) b.) Complex IV (Cyt c oxidase) c.) Complex V (ATP synthase) d.) complex II (Succinate-Q reductase) Complex II (succinate-Q reductase) (D) Which of the following would be consistent with an exergonic reaction? a.) ∆S would be negative b.) ∆G would be negative c.) ∆S would be positive d.)∆G would be positive ∆G would be negative (B) Which of the following describes the malate-aspartate shuttle system? a.) Carries NADH from the cytoplasm directly into the mitochondria b.) Generates 2.5 molecules of ATP in mitochondria per each NADH from glycolysis c.) Moves NADH from the mitochondria to the cytoplasm d.) Relies on malate dehydrogenase in the inner mitochondrial membrane e.) Requires reduction of pyruvate to lactate for oxidizing NADH Generates 2.5 molecules of ATP in mitochondria per each NADH from glycolysis (B) ATP is a high energy molecule that is often hydrolyzed during reactions. The energy within ATP is stored primarily in which of the following components of the molecule? a.) In the high energy phosphate bonds b.) In the adenine base c.) In the D-ribose group In the high energy phosphate bonds (A) Dinitrophenol is an uncoupler of the electron transport chain. The addition of dinitrophenol will have which of the following impacts? a.) Decrease the pH of the intermembrane space b.) Increase oxygen consumption c.) Decrease oxidation of NADH d.) Increase ATP production Increase oxygen consumption (B) In the malate aspartate shuttle, glutamate is converted to _______ in the mitochondria while aspartate is converted to _______ in the cytosol. a.) Oxaloacetate; malate b.) alpha-ketoglutarate; oxaloacetate c.) Oxaloacetate; glutamate d.) Aspartate; alpha-ketoglutarate e.) Malate; oxaloacetate alpha-ketoglutarate; oxaloacetate (B) The glycerophosphate shuttle is a major shuttle of most tissues. Which of the following best describes the transfer of electrons by this shuttle? a.) Electrons are directly transferred from glycerol-3-phosphate to NAD containing glycerol phosphate dehydrogenase b.) Electrons are directly transferred from glycerol-3-phosphate to an FAD containing glycerol phosphate dehydrogenase c.) Electrons are directly transferred from DHAP (dihydroxyacetone phosphate) to an FAD containing glycerol phospha Electrons are directly transferred from glycerol-3-phosphate to FAD containing glycerol phosphate dehydrogenase (B) Heat can be generated by brown adipose tissue in hibernating mammals. Which of the following is most likely the mechanism by which this occurs? a.) Increased ATP production by ATP synthase b.) Expression of a protein that uncouples the ETC c.) An increased pH gradient across the inner mitochondrial membrane d.) A decrease in oxygen consumption Expression of a protein that uncouples the ETC (B) Allosteric activators of hemoglobin will increase binding through what mechanism? Binding the protein, and keeping it in the "R" conformation An enzyme has a mutation within the substate binding site that reduces the binding of the coenzyme needed for covalent catalysis. What is likely to result as a consequence of this mutation? The enzyme will not be able to form the transition state complex How do most enzymes reduce activation energy needed to move a reaction forward? Providing an active site most complimentary to the transition state Under which energy conditions, AMP will bind to phosphofructokinase 1 (PFK1) and glycogen phosphorylase at site unique of the active site. This enhances the activity of these enzymes. This is an example of which of the following types of enzyme regulation? a.) Allosteric activation b.) Allosteric inhibition c.) Competitive inhibition d.) Covalent modification Allosteric activation (A) Which of the following best describes an enzyme inhibitor that increases the Km, but does not change the V-max? a.) Inhibition by covalent modification b.) A non-competitive inhibitor c.) An allosteric inhibitor d.) A competitive inhibitor A competitive inhibitor (D) An enzyme is participating in a general acid-base catalysis reaction with an optimal reaction pH of 6.0. If acid is added to the environment reducing the pH to 3, what is the likely impact to the rate of the reaction? a.) The rate is likely to decrease as the pH is out of optimal catalytic range. b.) The rate is likely to increase as the proton concentration has decreased. c.) The rate is likely to increase as the pH is within the optimal catalytic range. d.) The rate is likely to remain con The rate is likely to decrease as the pH is out of optimal catalytic range (A) An example of enzyme activation by cleavage is best illustrated by which of the following? a.) Activation of chymotrypsinogen to chymotrypsin b.) Phosphorylation of muscle glycogen phosphorylase c.) Cortisol binding an intracellular receptor d.) Activation of adenylyl cyclase to generate cAMP Activation of chymotrypsinogen to chymotrypsin (A) The association of DNA and histones can be modified by histone acetylation. A decrease in histone acetylation will have which of the following impacts on the association of DNA and histones? a.) Increase DNA: histone association b.) Decrease DNA: histone association c.) Have no impact on the association of DNA and histones Increase DNA: histone association (A) Which of the following is an example of enzyme regulation through covalent modification? a.) Binding of GTP to a monomeric G-protein b.) Phosphorylation of muscle glycogen phosphorylase c.) Digestion of misfiled proteins by lysosomes d.) Cleavage of chymotrypsinogen to chymotrypsin Phosphorylation of muscle glycogen phosphorylase (B) Domains are common structural elements that retain a particular function within a protein. What is an example of a protein domain? An arrangement of beta-strands connected by alpha-helices (BaBaB) What is the best description of the structure of heme? A planar porphyrin ring that binds iron What type of protein is likely to have a quaternary structure? A multimeric protein that contains multiple peptide chains What is the correct and complete electron transfer pathway for oxidative phosphorylation? NADH -- complex I -- CoQ -- Complex III -- cyt c -- complex IV If a mutation is made within the active site of an enzyme resulting in a decrease Km, what is true with respect to enzyme kinetics? The enzyme will require a lower substrate concentration to reach 1/2 V-max What amino acid would not be commonly found in the middle of an alpha-helical domain? Proline Children with cystinosis have growth delay and both renal and ocular issues due to accumulation of cysteine in cellular lysosomes. The defect involves a specific lysosomal membrane receptor that facilitates cystine removal from the cell, and an effective therapy has been administration of a drug with a similar structure to cystine. The therapy reflects the general principle that competitive inhibitors typically resemble what? Substrates or ligands that bind to the active site Chymotrypsin is a protease that cleaves peptide bonds. It is characterized as which of the following classes of enzymes? a.) Oxidoreductase b.) Transferase c.) Hydrolase d.) Ligase e.) Isomerase f.) Lyase Hydrolase (C) Alpha-helices and beta-sheets are primarily stabilized by what type of interaction? hydrogen bonding A 19-year-old boy is diagnosed with Creutzfeldt-Jakob Disease which is caused by the introduction of amyloid fold in the disease-causing protein. The introduction of this fold causes the protein to transition from a primarily alpha-helical structure to an aggregate of mostly beta-sheets. This change in protein structure (leading to disease) is best attributed to changes in which of the following? a.) Folding of the primary structures b.) Folding of the secondary structures c.) Folding of the Folding of the secondary structures (B) Cleavage of fructose 1, 6 bisphosphate to dihydroxyacetone and glyceraldehyde 3-phosphate is achieved by what class of enzymes? a.) Oxidoreductase b.) Transferase c.) Hydrolase d.) Ligase e.) Isomerase f.) Lyase Lyase (F) A new protein is discovered that increases in activity when the enzyme is phosphorylated on an exposed tyrosine residue. Phosphorylation of this amino acid is classified as what type of modification? Covalent modification A series of reactions have the following ∆G. A + B -- C where ∆G = -1 C + D -- E where ∆G = +3 E + F -- G where ∆G = -5 The overall ∆G for this series of reactions is determined by which of the following values? a.) -2 b.) -3 c.) +2 d.) +3 -3 (B) What component of the electron transport chain is not bound to the mitochondrial membrane? CoQ ATP is a high energy molecule that is often hydrolyzed during reactions. The energy within ATP is stored primarily in what components of the molecule? In the high energy phosphate bonds