UNE Biochemistry Midterm Study Bank with Complete Questions and Answers Graded A+, Exams of Nursing

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UNE Biochemistry Midterm Study Bank

with Complete Questions and Answers

Graded A+

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) - Correct Answer- 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 - Correct Answer-∆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 - Correct Answer-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 - Correct Answer-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 - Correct Answer-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 - Correct Answer-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 phosphate dehydrogenase d.) Electrons are directly transferred from glycerol-3- phosphate and DHAP - Correct Answer-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 - Correct Answer- Expression of a protein that uncouples the ETC (B) Allosteric activators of hemoglobin will increase binding through what mechanism? - Correct Answer-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? - Correct Answer-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? - Correct Answer-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 - Correct Answer-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 - Correct Answer-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 consistent as this change in the environment will not affect the kinetics. - Correct Answer-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 - Correct Answer-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 - Correct Answer-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 - Correct Answer-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? - Correct Answer-An arrangement of beta- strands connected by alpha-helices (BaBaB) What is the best description of the structure of heme? - Correct Answer-A planar porphyrin ring that binds iron What type of protein is likely to have a quaternary structure? - Correct Answer-A multimeric protein that contains multiple peptide chains What is the correct and complete electron transfer pathway for oxidative phosphorylation? - Correct Answer-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? - Correct Answer-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? - Correct Answer-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? - Correct Answer-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 - Correct Answer-Hydrolase (C) Alpha-helices and beta-sheets are primarily stabilized by what type of interaction? - Correct Answer-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 tertiary structures d.) Folding of the quaternary structures - Correct Answer- 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 - Correct Answer-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? - Correct Answer-Covalent modification A series of reactions have the following ∆G. A + B --> C where ∆G = - C + D --> E where ∆G = + E + F --> G where ∆G = - The overall ∆G for this series of reactions is determined by which of the following values? a.) - b.) - c.) + d.) +3 - Correct Answer--3 (B)

What component of the electron transport chain is not bound to the mitochondrial membrane? - Correct Answer-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? - Correct Answer-In the high energy phosphate bonds What best describes a protein domain? - Correct Answer-A relatively large pattern of 3-D structure that is recognized across many proteins Newborn screening results show a biotinidase deficiency in a 2-day old infant. This deficiency impairs the infant's ability to reuse and recycle biotin. Due to this enzymatic deficiency, the activity of which of the following enzymes is likely to be impaired? a.) Pyruvate dehydrogenase complex b.) Pyruvate carboxylase

c.) Transketolase d.) Amino transferase - Correct Answer-Pyruvate carboxylase (B) Which of the following events occurs during the formation of phosphophenolpyruvate during gluconeogenesis? a.) GPT is generated b.) Acetyl-CoA is utilized c.) Inorganic phosphate is consumed d.) Adenosine triphosphate (ATP) is generated e.) CO2 is required - Correct Answer-CO2 is required (E) Which of the following combinations of compounds is required to fully activate pyruvate carboxylase (+ indicates compound is needed; - indicates compound is not needed)?

1. Biotin (+) Acetyl-CoA (+) Oxaloacetate (+) Malate (-)
2. Biotin (+) Acetyl-CoA (+) Oxaloacetate (-) Malate (-)
3. Biotin (-) Acetyl-CoA (+) Oxaloacetate (+) Malate (+)
4. Biotin (-) Acetyl-CoA (-) Oxaloacetate (+) Malate (+) - Correct Answer-2. Biotin (+), Acetyl-CoA (+), Oxaloacetate (-), Malate (-) If unregulated, which of the following pairs of enzymes would represent a futile cycle? a.) Pyruvate kinase and fructose 1,6-bisphosphatase b.) Fructose 1,6-bisphosphatase and phsophofructokinase- (PFK-1) c.) Glucose-6-phosphatase and phosphofructokinase-1 (PFK-1)

d.) Pyruvate carboxylase and phosphoenolpyruvate carboxykinase e.) Pyruvate kinase and pyruvate carboxylase - Correct Answer-Fructose 1,6-bisphosphatase and PFK-1 (B) During an overnight fast, which of the following is the major source of blood glucose? a.) Hepatic glycogenolysis b.) Muscle glycogenolysis c.) Dietary glucose from the intestine d.) Glycerol from lipolysis e.) Gluconeogenesis - Correct Answer-Hepatic glycogenolysis (A)

What sequence of enzyme allows for the synthesis of glycogen from glucose-6-phosphate? a.) Phsophoglucomutase, amylo-(1,4a1,6)-transglycosylase, UDP-glucose pyrophosphorylase, glycogen synthase b.) Phosphoglucomutase, UDP-glucose phosphorylase, glycogen synthase, amylo-(1,4a1,6)-transglycosylase c.) Phosphoglucomutase, UDP-glucose phosphorylase, amylo- (1,4a1,6)-transglycosylase, glycogen phosphorylase d.) UDP-glucose pyrophosporylase, phosphoglucomutase, glycogen synthase, amylo-(1,4a1,6)-transglycosylase e.) UDP-glucose pyrophosphorylase, phosphoglucomutase, amylo-(1,4a1,6)-transglycosylase, glycogen synthase - Correct Answer-Phosphoglucomutase, UDP-glucose phosphorylase, glycogen synthase, amylo-(1,4a1,6)-transglycosylase (B) The process of gluconeogenesis primarily takes place in which of the following tissue?

a.) Skeletal muscle b.) Red blood cells c.) Brain d.) Liver - Correct Answer-Liver (D) When the insulin to glucagon ratio is low, glycogenolysis is activated in the liver. Which of the following is the primary fate of the glucose-6-phosphate released under these conditions? a.) Dephosphorylated and released into the blood to maintain blood glucose b.) Released into the blood as glucose-6-phosphate c.) Directly used as a substrate for gluconeogenesis

d.) Immediately converted to fructose-6-phosphate used as a substrate for glycolysis - Correct Answer-Dephosphorylated and released into the blood to maintain blood glucose (A) Which of the following enzymes is correctly paired with its activator? a.) Pyruvate kinase; citrate b.) Glyceraldehyde 3-phoshpate dehydrogenase; citrate c.) Pyruvate dehydrogenase complex; pyruvate d.) Isocitrate dehydrogenase; NADH - Correct Answer- Pyruvate dehydrogenase complex; pyruvate (C) Which of the following are the 2 primary products of the pentose phosphate pathway? a.) ATP and NADPH

b.) Oxaloacetate and acetyl-CoA c.) Sorbitol and fructose d.) Ribose-5-phosphate and NADPH - Correct Answer-Ribose- 5-phosphate and NADPH (D) A family presents for genetic counseling. The couple has two female children who are alive and well, however their infant son recently died in the nursery with severe hemolysis and jaundice. The wife recalls she lost a brother in infancy with severe hemolysis (rupturing of red blood cells), induced after a viral infection. The physician suspects glucose-6-phosphate dehydrogenase deficiency, this would result in a deficiency in which of the following compounds? a.) Deoxyribose and NADP (nicotinamide adenine dinucleotide phosphate) b.) Glucose and lactate c.) Lactose and NADPH

d.) Ribose and NADPH e.) Sucrose and NAD (nicotinamide adenine dinucleotide) - Correct Answer-Ribose and NADPH (D) Which of the following is NOT stimulated by high levels of insulin? a.) Fatty acid synthesis b.) Glycolysis c.) Amino acid catabolism d.) Glycogen synthesis - Correct Answer-Amino acid catabolism (C) Which of the following are the two major contributors to maintaining blood glucose levels during fasting?

a.) Hepatic glycogenolysis and gluconeogenesis b.) Skeletal muscle glycogenolysis and gluconeogenesis c.) Hepatic glycogenolysis and glycolysis d.) Ketogenesis and gluconeogenesis e.) Protein catabolism and lipolysis - Correct Answer-Hepatic glycogenolysis and gluconeogenesis (A) In order for glucose to be retained within the cell, which of the following modifications must occur to the muscle? a.) Acetylation b.) Ionization c.) Phosphorylation d.) Methylation - Correct Answer-Phosphorylation (C)