UNE BIOCHEMISTRY UNIT 1 TEST QUESTIONS AND ANSWERS 2023

-3 A series of reactions have the following ΔG. A + B -- C ΔG = -1 C + D -- E ΔG = +3 E + F -- G ΔG = -5 The overall ΔG for this series of reactions is determined to be which of the following values? ΔG0 would be negative What is consistent with an exergonic reaction? Increase oxygen consumption Dinitrophenol is an uncoupler of the electron transport chain. The addition of dinitrophenol will have which of the following impacts? NADH → complex I → CoQ → complex III → cyt c → complex IV Which of the following describes a correct and complete electron transfer pathway necessary for oxidative phosphorylation? Complex I (NADH Q-oxidoreductase) A 19-year-old male is being evaluated for muscle weakness. Evaluation of a muscle biopsy revealed normal rates of succinate oxidation but very low rates of pyruvate oxidation. Further testing determined normal levels of enzymatic activity in both malate dehydrogenase and pyruvate dehydrogenase. Based on this data, the patient may have a mutation in a gene encoding for which mitochondrial protein? Malate The malate-aspartate shuttle is used to move reducing equivalents of cytosolic NADH into the mitochondria where it can be oxidized. Which of the following compounds is used to move the reducing equivalents from cytosolic NADH into the mitochondria? α-ketoglutarate; oxaloacetate In the malate aspartate shuttle, glutamate is converted to _________ in the mitochondria while aspartate is converted to ___________ in the cytosol. 1 ATP is used to carry energy within the cell. The majority of energy in ATP is stored within which of the following bonds indicated on the image below? CoQ Which of the following components of the electron transport chain is not bound to the mitochondrial membrane? Generates 2.5 molecules of ATP in mitochondria per each NADH from glycolysis. Which of the following is a true statement with regards to the malate-aspartate shuttle system? It reduces the catalytic activity of the enzyme A 28-year-old male is recently diagnosed with HIV. As part of his treatment he is prescribed Nevirapine which interferes with retroviral reverse transcriptase enzyme. Using the graph below, which of the following best describes the impact of this drug on its target? Substrates or ligands that bind the active site 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 cysteine removal from the cell. An effective therapy has been administration of a drug with a similar structure to cysteine. This therapy reflects the general principle that competitive inhibitors typically resemble the structure of which of the following? feedback inhibition The following represents a series of reactions. As levels of B increase, this will decrease the conversion of S3 to B. Which of the following best describes this type of regulation in a biosynthetic pathway? Activation of chymotrypsinogen to chymotrypsin An example of enzyme activation by cleavage is best illustrated by which of the following? Increase DNA: histone association 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? Glucokinase has a higher Km than hexokinase. Use the figure below to compare the activities of glucokinase and hexokinase. Based on this information, which of the following is a true statement? The enzyme will require a lower substrate concentration to reach ½Vmax If a mutation is made within the active site of an enzyme resulting in a decrease in Km, which of the following will be true with respect to the enzyme kinetics? A competitive inhibitor Which of the following best describes an enzyme inhibitor that increases the Km but does not change the Vmax? Allosteric activation Under low energy conditions, AMP will bind to phosphofructokinase I and glycogen phosphorylase at site unique to the active site. This enhances the activity of these enzymes. This is an example of which of the follow types of enzyme regulation? A section of a protein structure sufficient to perform a particular chemical or physical task Which of the following best describes a protein domain? Troponin A 55-year old man is brought to the emergency room with a chief complaint of chest pain and tingling in his left arm. Elevation of which of the following enzymes in circulation would be most indicative of a myocardial infarction? Hydrogen bonding α-helices and β-sheets are primarily stabilized by which of the following interactions? Folding of the secondary structures A 19-year-old boy is diagnosed with Creutzfeldt-Jakob Disease which is caused by the introduction of an amyloid fold in the disease-causing protein. The introduction of this fold causes the protein to transition from a primarily α-helical structure to an aggregate of mostly β-sheets. This change in protein structure (leading to disease) is best attributed to changes in which of the following? Secondary structure of the protein An α-helical arrangement of amino acids is considered to be what level of protein structure? An arrangement of β-strands connected by α-helices (βαβαβ) Domains are common structural elements that retain a particular function within the protein. Which of the following is an example of a protein domain? Hydrolases Chymotrypsin is a protease that cleaves peptide bonds. It is characterized as which of the following classes of enzymes? A newly synthesized strand of amino acids Which of the following is the best description of primary protein structure?