MWU Biochemistry Exam 2 with correct answers 2023-24

MWU Biochemistry Exam 2 D) In gel filtration, large proteins move most rapidly, but in PAGE, small proteins move most rapidly. - correct answer Which of the following is true regarding gel filtration chromatography and PAGE? A) In both, small proteins move most rapidly. B) In both, large proteins move most rapidly. C) In PAGE, large proteins move most rapidly but in gel filtration, small proteins move most rapidly. D) In gel filtration, large proteins move most rapidly, but in PAGE, small proteins move most rapidly. E) None of the above. D) isoelectric focusing and ion-exchange chromatography - correct answer Two proteins are similar in size but differ significantly in the number of acidic and basic amino acids. Which of the following techniques would be best suited to separating these two proteins? A) SDS-PAGE and gel-filtration chromatography B) isoelectric focusing and dialysis C) immunoprecipitation and affinity chromatography D) isoelectric focusing and ion-exchange chromatography E) None of the above. D) isoelectric focusing and ion-exchange chromatography - correct answer Two proteins are similar in the number of acidic and basic amino acids but are different significantly in size. Which of the following techniques would be best suited to separating these two proteins? A) SDS-PAGE and gel-filtration chromatography B) isoelectric focusing and dialysis C) immunoprecipitation and affinity chromatography D) isoelectric focusing and ion-exchange chromatography E) None of the above. C) RNA contains U instead of T. - correct answer The difference in RNA bases compared to DNA bases is A) RNA contains A instead of T. B) RNA contains U instead of G. C) RNA contains U instead of T. D) RNA contains A instead of U. E) None of the above. D) A nucleotide is a nucleoside with a phosphate ester linked to the sugar. - correct answer How does a nucleotide differ from a nucleoside? A) Nucleosides are found in DNA, whereas nucleotides are found in RNA. B) Purines are only found in nucleotides. C) Nucleosides contain only deoxyribose sugars. D) A nucleotide is a nucleoside with a phosphate ester linked to the sugar. E) None of the above. C) semiconservative - correct answer Replication takes place in which manner? A) conservative B) random C) semiconservative D) N-linked E) None of the above. D) All of the above. - correct answer The feature(s) of DNA deduced by Watson and Crick include A) two antiparallel polynucleotide chains coiled in a helix around a common axis. B) that the pyrimidine and purine bases lie on the inside of the helix. C) that the bases are nearly perpendicular to the axis. D) All of the above. E) None of the above. B) van der Waals interactions. - correct answer The chemical forces that contribute to the stability of the DNA due to the base stacking present in the DNA helix are A) hydrogen bonds. B) van der Waals interactions. C) disulfide bonds. D) C and B. E) None of the above. B) Tm. - correct answer The temperature at which half of the DNA helical structure is lost is called the A) denaturation temperature. B) Tm. C) annealing temperature. D) dehybridization temperaure. E) replication temperature. C) annealing. - correct answer The process of rehybridizing melted DNA is called A) denaturation. B) Tm. C) annealing. D) dehybridization. E) replication. C) negative supercoiling. - correct answer Unwinding prior to ligation results in A) relaxed DNA. B) a wider major groove. C) negative supercoiling. D) positive supercoiling. E) None of the above. E) All of the above. - correct answer RNA A) is oxygenated on the 2¢ of ribose. B) can form non-Watson-Crick base pairings. C) uses metals to stabilize folding. D) may form triplet base pairings. E) All of the above. A) ribonucleotides. - correct answer Both de novo and salvage paths are used in the synthesis of A) ribonucleotides. B) deoxyribonucleotides. C) dideoxyribonucleotides. D) All of the above. E) None of the above. E) None of the above. - correct answer TMP is made from A) dTMP. B) dUMP. C) CTP. D) ATP. E) None of the above. E) A, B, and C. - correct answer In de novo synthesis, the pyrimidine ring is assembled using A) bicarbonate. B) aspartate. C) glutamine. D) A and B. E) A, B, and C. A) ammonia or an amino group. - correct answer The displacing nucleophile in pyrimidine synthesis is typically A) ammonia or an amino group. B) a metal ion. C) coenzyme A. D) All of the above. E) None of the above. D) A or B. - correct answer Inosinate can be converted to A) AMP. B) GMP. C) UMP. D) A or B. E) A, B, or C. C) NADPH. - correct answer The ultimate reductant in synthesis of deoxyribonucleotides is A) FADH2. B) NADH. C) NADPH. D) quinone. E) None of the above. B) methotrexate. - correct answer The competitive inhibitor(s) of dihydrofolate reductase is (are) A) aminopterin. B) methotrexate. C) fluorouracil. D) A and B. E) B and C. A) xanthine oxidase. - correct answer Allopurinol is used to treat gout and is an inhibitor of the enzyme(s) A) xanthine oxidase. B) xanthine hydrolase. C) hypoxanthine-guanine phosphoribosyltransferase. D) All of the above. E) None of the above. C) stabilization the transition state - correct answer What is the common strategy by which catalysis occurs? A) increasing the probability of product formation B) shifting the reaction equilibrium C) stabilization the transition state D) All of the above. E) None of the above. C) a large number of weak interactions at the active site. - correct answer An enzyme will specifically bind its substrate because of____________ A) a tight lock and key binding mechanism. B) a high number of hydrophobic amino acids in the center of the protein. C) a large number of weak interactions at the active site. D) additional nonprotein cofactors. E) None of the above. E) All of the above. - correct answer Examples of cofactors include: A) Zn+2, Mg+2, and Ni+2. B) biotin and thiamine pyrophosphate. C) pyridoxal phosphate and coenzyme A. D) B and C. E) All of the above. E) None of the above. - correct answer A cofactor is best defined as ______________. A) another protein B) a covalently bound inorganic molecule C) a small molecule that holds the substrate in the active site D) a molecule responsible for most of the catalytic activity of the enzyme E) None of the above. E) None of the above. - correct answer Which of the following is true? A) Enzymes force reactions to proceed in only one direction. B) Enzymes alter the equilibrium of the reaction. C) Enzymes alter the standard free energy of the reaction. D) All of the above. E) None of the above. A) the difference between the substrate and the transition state. - correct answer The Gibbs free energy of activation is: A) the difference between the substrate and the transition state. B) the difference between the substrate and the product. C) the difference between the product and the transition state. D) All of the above. E) None of the above. D) zero - correct answer At equilibrium, the Gibb's free energy is ___________. A) a positive value B) neutral C) a negative value D) zero E) one E) None of the above. - correct answer The active site of an enzyme_____________. A) is a series of amino acids that bind the enzyme B) is a linear sequence of amino acids that react with each other C) binds covalently to the substrate D) allows water to enter into the solvate the substrate E) None of the above. E) increase the km for the enzyme - correct answer Competitive enzyme inhibitors A) only work if covalently bonded to enzyme active sites B) decrease the Vmax of the enzyme C) decrease the turn over number for the enzyme D) increase the turn over number for the enzyme E) increase the km for the enzyme B) decrease the Vmax for the enzyme - correct answer Non-Competitive enzyme inhibitors A) decrease the Km for the enzyme B) decrease the Vmax for the enzyme C) increase the turn over number for the enzyme D) increase the Vmax for the enzyme E) are always derivatives of water soluble vitamins C) allosteric inhibitors stabilise the R state - correct answer Regarding Allosteric enzymes, A) always consist of single polypeptide chains B) always obey Michaelis - Menten kinetics C) allosteric inhibitors stabilise the R state D) allosteric activators stabilise the T state E) allosteric inhibitors stabilise the T state B) bind to membrane receptors and transmit information across a membrane without traversing the membrane. - correct answer Most signal molecules: A) easily diffuse through the membrane and bind to a receptor in the cytoplasm. B) bind to membrane receptors and transmit information across a membrane without traversing the membrane. C) carry out functions in the nucleus after binding to a receptor in the cell membrane. D) A and C. E) A, B, and C. E) A, B, and C. - correct answer Examples of second messengers include: A) cAMP. B) calcium ion. C) diacylglycerol. D) A and B. E) A, B, and C. D) All of the above. - correct answer Advantages of second messengers include: A) the signal can be amplified by making many second messengers. B) can freely diffuse to other sites within the cell. C) a few common second messengers can be used in multiple signaling pathways. D) All of the above. E) None of the above. A) tyrosine, serine, threonine - correct answer Which of the following amino acids can be phosphorylated? A) tyrosine, serine, threonine B) tyrosine, serine, tryptophan C) serine, threonine, asparagine D) histidine, serine, phenylalanine E) tyrosine, methionine, tryptophan B) GDP - correct answer Which form of the guanyl nucleotide is bound in the unactivated state? A) GTP B) GDP C) GMP D) dGTP E) None of the above. C) protein dephosphorylation by phosphatases. - correct answer The mechanism by which insulin-signaling processes might be terminated includes: A) change in temperature. B) the aggregation of all protein subunits. C) protein dephosphorylation by phosphatases. D) All of the above. E) None of the above. A) It causes an exchange of GTP for bound GDP. - correct answer How does the binding of a hormone to a receptor activate a G-protein? A) It causes an exchange of GTP for bound GDP. B) It causes the γ subunit to be released from binding to the β subunit. C) It causes an exchange of GDP for bound GTP. D) A and B. E) None of the above. C) The Ga receptors have intrinsic GTPase activity, hydrolyzing GTP to GDP and Pi. - correct answer Why is bound GTP considered a "clock"? A) It behaves in specific time intervals. B) GTP is exchanged for GDP after binding to adenylate cyclase. C) The Ga receptors have intrinsic GTPase activity, hydrolyzing GTP to GDP and Pi. D) All of the above. E) None of the above. A) phospholipase C. - correct answer The enzyme responsible for induction of the phosphoinositide cascade is: A) phospholipase C. B) phospholipase A. C) C-dependent protein (CDP). D) All of the above. E) None of the above. A) diacylglyercol and inositol 1,4,5-triphosphate - correct answer What are the two messenger products formed by cleavage of PIP2? A) diacylglyercol and inositol 1,4,5-triphosphate B) diacylglyercol and inositol 1,3,5-triphosphate C) diacylglyercol and inositol 1,3-diphosphate D) diacylglyercol phosphate and inositol 1,4,5-trisphosphate E) None of the above. B) form dimers. - correct answer Cross-phosphorylation is possible when two receptor proteins with kinase domains A) are cleaved. B) form dimers. C) are internalized into organelles. D) All of the above. E) None of the above. D) A and B. - correct answer Example(s) of disease(s) caused by altered G-protein activity include A) whooping cough. B) cholera. C) diabetes. D) A and B. E) B and C. A) All life-forms use 20 amino acids for the biosynthesis of proteins - correct answer Concerning amino acids: A) All life-forms use 20 amino acids for the biosynthesis of proteins B) Only 20 types of amino acids are present in the natural life-forms C) All life-forms can synthesize 21 types of standard amino acids D) The a-carbon in amino acids refers to the carbon atom in the carboxyl group E) Both L-amino acids and D-amino acids are used in protein biosynthesis C) E - correct answer Which of the following is the single letter abbreviation for glutamic acid? A) G B) P C) E D) Z E) L E) the sequence of amino acids in a protein - correct answer Edman degradation is used to determine: A) the position of disulfide bonds in a protein B) the amino acid content of a protein C) C-terminal amino acid in a protein D) the molecular weight of a protein E) the sequence of amino acids in a protein D) Quaternary structure - correct answer Haemoglobin consists of an a and b chain. This is an example of: A) Primary structure B) Secondary structure C) Tertiary Structure D) Quaternary structure E) Penatmeric structure C) Size - correct answer In gel filtration chromatography, proteins are separated by: A) Charge B) Affinity C) Size D) Density E) Avidity B) 30% - correct answer The percentage of adenine in a given DNA sample is what, if the percentage of guanine is 20%. A) 20% B) 30% C) 40% D) 10 % E) 29% D) heterochromatin form - correct answer Human DNA is of the A) A form B) B form C) Z form D) heterochromatin form E) euchromatin form D) Ciprofloxacin - correct answer Which of the following is an inhibitor of bacterial topoisomerase A) Camptothecin B) Penicillin C) Fluoramide D) Ciprofloxacin E) Amphotericin C) 8 subunits - correct answer The protein histone is synthesized using A) 10 subunits B) 11 subunits C) 8 subunits D) 12 subunits E) 13 subunits D) by chemical denaturants - correct answer Proteins are generally denatured A) by mild detergents B) by cooling to 0OC C) at pH 7 D) by chemical denaturants E) by moderate salt levels (e.g. 100 mmol/litre KCl) E) A, B and C. - correct answer The major purpose(s) for which organisms require energy is/are: A) performance of mechanical work. B) active transport. C) synthesis of biomolecules. D) A and C. E) A, B, and C. B) catabolic. - correct answer Reaction pathways that transform fuels into cellular energy are: A) anabolic. B) catabolic. C) allobolic. D) All of the above. E) None of the above. E) A, B, and C. - correct answer Which of the following molecule(s) have a higher phosphoryl-transfer potential than ATP? A) phosphoenolpyruvate B) creatine phosphate C) 1,3-bisphosphoglycerate D) A and B. E) A, B, and C. C) coenzyme A: acyl - correct answer Which is the correct coenzyme: carrier pair? A) NADH: acyl B) tetrahydrofolate: electrons C) coenzyme A: acyl D) lipoamide: aldehyde. E) thiamine pyrophosphate: glucose B) The enzyme that catalyzes this reaction couples it with the hydrolysis of ATP to ADP and inorganic phosphate, resulting in an overall ΔGoˊ of -14.2 kJ/mol. - correct answer The phosphorylation of fructose-6-phosphate is an endergonic reaction with a ΔGoˊ of 16.3 kJ/mol. How do cells overcome this thermodynamic barrier for this reaction under standard conditions? A) The enzyme that catalyzes this reaction couples it with the condensation of ADP and inorganic phosphate, resulting in an overall ΔGoˊ of -46.8 kJ/mol. B) The enzyme that catalyzes this reaction couples it with the hydrolysis of ATP to ADP and inorganic phosphate, resulting in an overall ΔGoˊ of -14.2 kJ/mol. C) This reaction will proceed to the right because the Keq is small. D) This reaction will proceed to the right because the Keq is negative. E) By uncoupling the reaction to the hydrolysis of ATP, the reaction can be driven forward. B) acetyl CoA - correct answer What molecule initiates the citric acid cycle by reacting with oxaloacetate? A) pyruvate B) acetyl CoA C) oxaloacetate D) All of the above. E) None of the above. A) conversion of succinyl CoA to succinate - correct answer In which reaction is GTP (or ATP) directly formed in the citric acid cycle? A) conversion of succinyl CoA to succinate B) decarboxylation of a-ketoglutarate C) conversion of isocitrate to a-ketoglutarate D) All of the above. E) None of the above. C) the conversion of succinate to fumarate - correct answer In which step of the citric acid cycle is FADH2 formed? A) the conversion of succinate to malate B) the conversion of succinate to oxaloacetate C) the conversion of succinate to fumarate D) the conversion of malate to oxaloacetate E) None of the above. D) A primary product of the CAC is NADH, the principle electron donor to the O2, the last electron acceptor in the electron-transport system. - correct answer The citric acid cycle (CAC) is activated in the presence of oxygen, but what is the link between the CAC and oxygen? A) Oxygen is an allosteric activator for citrate synthase. B) The presence of O2 in the mitochondrial matrix releases CO2 into the cytosol. C) The one substrate-level phosphorylation in the CAC can occur in the absence of oxygen. D) A primary product of the CAC is NADH, the principle electron donor to the O2, the last electron acceptor in the electron-transport system. E) The iron-sulfur centre requires oxygen to be in the appropriate oxidation state. A) transport of protons across the inner mitochondrial membrane from inside the matrix to the intermembrane space. - correct answer Electron flow down the electron-transport chain leads to the: A) transport of protons across the inner mitochondrial membrane from inside the matrix to the intermembrane space. B) transport of protons across the inner mitochondrial membrane from the intermembrane space into the matrix. C) coupled synthesis of GTP. D) a dangerous imbalance of K+ ions across the mitochondiral membrane. E) None of the above. C) ubiquinone. - correct answer Coenzyme Q is also called: A) NADH. B) oxidoreductase. C) ubiquinone. D) All of the above. E) None of the above. A) a protein that transfers electrons, and that also contains a heme prosthetic group - correct answer What is a cytochrome? A) a protein that transfers electrons, and that also contains a heme prosthetic group B) a chloroplast protein that transfers electrons, and that also contains an iron sulfur prosthetic group C) a protein that pumps ATP, and that also contains iron D) All of the above. E) None of the above. B) Modern mitochondria have circular DNA similar to bacteria: endosymbiotic event. - correct answer What evidence is there that modern mitochondria are the result of a single ancient event? What is the event called? A) Modern mitochondria have specific transcription and translation machinery similar to viruses: viral endosymbiosis event. B) Modern mitochondria have circular DNA similar to bacteria: endosymbiotic event. C) Modern mitochondria are the only organelles in the cell with a double membrane: electrontransfer event. D) Modern mitochondria have DNA polymerase sequences similar to a single bacteria: replication event. E) None of the above. C) proton - correct answer What type of gradient is critical to ATP formation by oxidative phosphorylation? A) sodium ion B) chloride ion C) proton D) potassium ion E) None of the above. B) 26 out of 30 - correct answer When glucose is totally oxidized to CO2 and H2O, how many ATP molecules are made by oxidative phosphorylation relative to the maximum yield? A) 12 out of 30 B) 26 out of 30 C) 26 out of 32 D) 12 out of 38 E) None of the above. A) The flow of electrons from NADH to CoQ is blocked. - correct answer What is the chemical effect of rotenone on aerobic metabolism? A) The flow of electrons from NADH to CoQ is blocked. B) The flow of electrons from Cyt a-a3 to oxygen is blocked. C) Oligomycin blocks the proton transfer through F0 of ATP synthase and therefore blocks the phosphorylation of ADP to form ATP. D) The transport of ATP out of and ADP into the mitochondria are blocked. E) Oxidative phosphorylation is uncoupled from electron transport and all the energy is lost as heat. D) A and B. - correct answer The proton motive force consists of _____________. A) a chemical gradient B) a proton gradient. C) an electron gradient D) A and B. E) A, B, and C. A) transport of protons across the inner mitochondrial membrane from inside the matrix to the intermembrane space. - correct answer Electron flow down the electron-transport chain leads to the A) transport of protons across the inner mitochondrial membrane from inside the matrix to the intermembrane space. B) transport of protons across the inner mitochondrial membrane from the intermembrane space into the matrix. C) coupled synthesis of GTP. D) a dangerous imbalance of K+ ions across the mitochondiral membrane. E) None of the above. A) uncoupler - correct answer A diet pill that acts to increase oxygen consumption and a high amount of electron transport without ATP production is likely what kind of compound? A) uncoupler B) ATP synthase activator C) site I inhibitor D) site II activator E) cyanide D) Many of the reactions in the citric acid cycle and ATP synthesis are driven by accessibility of substrates and differential gradients across the inner membrane. - correct answer Why is it not surprising that substances such as intermediates for the citric acid cycle, protons, inorganic phosphate, nucleotide phosphates, and many others have their transport across the inner membrane regulated? A) Regulated transport allows for more effective substrate cycling. B) Ultimately all electrons flow into the electron-transport chain, which regulates electron flow from the matrix to the inner membrane space. C) The experiment where bacteriorhodopsin and ATP synthase were inserted into reconstituted vesicles showed that biochemically, membranes control the movement of electrons in the respiratory chain. D) Many of the reactions in the citric acid cycle and ATP synthesis are driven by accessibility of substrates and differential gradients across the inner membrane. E) It is necessary to segregate the enzymes capable of substrate level phosphorylation during anaerobic respiration. D) B and C - correct answer The major site(s) of glycogen storage is (are): A) adipose tissue. B) liver. C) skeletal muscle. D) B and C E) A, B, and C B) glycogen phosphorylase. - correct answer The key enzyme in glycogen degradation is: A) glycogen phosphatase. B) glycogen phosphorylase. C) glucose 1-phosphate synthase. D) All of the above. E) None of the above. A) phosphoglucomutase. - correct answer Conversion of glucose 1-phosphate to glucose 6-phosphate is carried out by the enzyme: A) phosphoglucomutase. B) kinase 1-P. C) phosphoglycerate mutase. D) All of the above. E) None of the above. A) for glucose export to other tissues when glucose levels are low - correct answer What is the function of liver glycogen degradation? A) for glucose export to other tissues when glucose levels are low B) to maintain glucose levels after a large meal C) to provide for the large energy needs of the liver D) All of the above. E) None of the above. B) glucagon and epinephrine. - correct answer Two critical hormones that signal for glycogen breakdown are: A) insulin and epinephrine. B) glucagon and epinephrine. C) glucagon and insulin. D) All of the above. E) None of the above. E) None of the above. - correct answer The activated glucose donor of glycogen synthesis is: A) glucose 1-phosphate. B) glucose. C) ATP. D) UTP. E) None of the above. B) glygogenin. - correct answer At the centre of a glycogen molecule is: A) glucose. B) glygogenin. C) UDP-glucose. D) glycogen synthase. E) glycogen phosphorylase. A) glycogen synthase - correct answer What enzyme(s) is (are) required to synthesize a-1,4-glycosidic bonds in glycogen? A) glycogen synthase B) UDP-glucose phosphorylase C) branching enzyme D) A and B E) B and C E) All of the above. - correct answer Glycogenin: A) consists of dimmer proteins. B) self assembles 10-20 glycosyl units. C) is the primer for glycogen synthase. D) B and C E) All of the above. D) Type II diabetes. - correct answer ___________ results from a loss or inactive insulin receptors A) Hypoglycemia B) Hyperinsulinemia C) Type I diabetes D) Type II diabetes. E) None of the above. D) A and B. - correct answer Which of the following are reasons that glucose is a common metabolic fuel used by living organisms? A) It has a stable ring structure and is unlikely to glycosylate proteins. B) It has been found as one of the monosaccharides formed under prebiotic conditions. C) It is the only sugar used by the brain. D) A and B. E) A, B, and C. E) A and B. - correct answer What is the purpose of phosphorylating glucose in cytosol? A) to trap glucose in the cell B) to destabilize glucose and facilitate the next series of metabolic steps C) to convert it to a more soluble form D) All of the above. E) A and B. B) glyceraldehyde-3-phosphate and dihydroxyacetone phosphate - correct answer What two 3-carbon molecules are generated by the cleavage of fructose-1,6-bisphosphate? A) glyceraldehyde-3-phosphate and 3-phosphoglycerate B) glyceraldehyde-3-phosphate and dihydroxyacetone phosphate C) pyruvate and phosphoenolpyruvate D) enolase and 2-phosphoglycerate E) glyceraldehyde-3-phosphate and pyruvate B) Binding of substrate induces cleft closing. - correct answer What is a common mechanistic feature of kinases? A) Phosphoryl groups are transferred from AMP to an acceptor. B) Binding of substrate induces cleft closing. C) It converts aldoses to ketoses. D) All of the above. E) None of the above. B) ATP synthesis when the phosphate donor is a substrate with high phosphoryl transfer potential - correct answer What is substrate-level phosphorylation? A) phosphorylation of AMP by ATP B) ATP synthesis when the phosphate donor is a substrate with high phosphoryl transfer potential C) phosphorylation of glycolytic intermediates D) phosphorylation of ATP coupled to an ion gradient E) ATP and AMP synthesis from two molecules of ADP D) All of the above. - correct answer What are the primary metabolic fates of pyruvate? A) ethanol B) lactate C) acetyl CoA D) All of the above. E) None of the above. D) All of the above. - correct answer Biotin provides __________ for the pyruvate carboxylase reaction. A) a long flexible arm for active site location of substrate B) carboxylation of pyruvate C) group transfer from one site of the enzyme to another D) All of the above. E) None of the above. D) GTP. - correct answer The phosphoryl donor in the formation of phophoenolpyruvate is: A) pyruvate. B) PEP. C) ATP. D) GTP. E) inorganic phosphate. B) liver - correct answer The major site for gluconeogenesis is in which of the following tissues? A) brain B) liver C) striated muscle D) adipose E) red blood cells A) increases - correct answer High blood sugar after a meal _______ the level of insulin released by the pancreas. A) increases B) decreases C) has no effect on D) chronically activates E) chronically inhibits D) All of the above. - correct answer In general, the liver_______________. A) will not utilize glucose under starvation/low energy conditions. B) acts as a glucose buffer for the rest of the body. C) is a producer of glucose for the body under low energy conditions. D) All of the above. E) None of the above. D) type II diabetes - correct answer Insulin resistance is a hallmark of__________. A) PEPCK activation B) pancreatic disorder C) type I diabetes D) type II diabetes E) long-term starvation C) glucose; the Cori cycle - correct answer Lactate produced in muscle tissue is converted to _________ by __________ . A) glucose; gluconeogenesis B) lactate; the Cori cycle C) glucose; the Cori cycle D) pyruvate; glycolysis E) ATP; the Krebs cycle C) lactate and amino acids. - correct answer The primary raw materials for gluconeogenesis are: A) galactose and sucrose. B) pyruvate and oxaloacetate. C) lactate and amino acids. D) fructose and glycerol. E) lactose and lactate. B) six - correct answer How many high-energy phosphate bonds are consumed in gluconeogenesis? A) three B) six C) two D) four E) one A) NADPH. - correct answer ATP is called the energy currency. The currency of biosynthetic reducing power is A) NADPH. B) NADH. C) AMP. D) ADP. E) None of the above. E) None of the above. - correct answer The pentose phosphate pathway A) is stimulated by NADH. B) is stimulated by NADPH. C) operates primarily in non-dividing cells. D) is contained within the mitochondria of adipose cells. E) None of the above. D) A and B - correct answer The sugar(s) that is (are) converted into ribulose 5-phosphate by a single enzymatic step is (are): A) ribose 5-phosphate. B) xyulose 5-phosphate. C) erythrose 4-phosphate. D) A and B E) B and C E) B and C - correct answer The purpose of the pentose phosphate pathway is to: A) generate ATP. B) generate NADPH. C) synthesize five-carbon sugars. D) A and B E) B and C E) B and C - correct answer Reduced glutathione maintains red blood cell structure by: A) protecting against falciparum malaria. B) maintaining hemoglobin structure. C) preventing Heinz body formation. D) A and C E) B and C B) Peroxides cause damage to red blood cells because there is no NADPH being produced. - correct answer Section 26.3 in the text highlights several conditions due to a deficiency in glucose 6-phosphate dehydrogenase. All of these conditions include anemia as a symptom. Why? A) The oxidized form of glutathione is the substance that normally eliminates peroxides and is depleted in the absence of NADPH. B) Peroxides cause damage to red blood cells because there is no NADPH being produced. C) Red blood cells with diminished glucose 6-phosphate dehydrogenase activity have an overactive response to oxidative stress. D) Reactive oxygen species formation is enhanced by reduced glutathione leading to cell membrane disruption. E) There is an abundance of NADPH in red blood cells due to the loss of mitochondria. D) A and B - correct answer NADPH is required for which of the following detoxification reactions or enzymes? A) cytochrome P450 monooxygenase B) reduction of glutathione(ox). C) deamination of serine D) A and B E) All of the above. C) used as metabolic fuel. - correct answer Surplus amino acids are A) stored in proteasomes. B) stored in protein scaffolds. C) used as metabolic fuel. D) All of the above. E) None of the above. E) None of the above. - correct answer The urea cycle is A) a system for protein degradation and turnover. B) responsible for nitrogen fixing. C) responsible for the filtering of nitrogen by the kidney. D) a system involved in transporting nitrogen from muscle to the liver. E) None of the above. B) NH4+. - correct answer Ammoniotelic organisms excrete excess nitrogen as A) N2H8. B) NH4+. C) urea. D) All of the above. E) None of the above. E) B and C. - correct answer Ketogenic amino acids are degraded to which of the following metabolites? A) pyruvate B) acetyl CoA C) acetoacetate D) All of the above. E) B and C. B) methionine, isoleucine, valine - correct answer Which amino acids supply carbons for eventual entry into metabolism as succinyl CoA? A) methionine, valine, leucine B) methionine, isoleucine, valine C) isoleucine, valine, leucine D) All of the above. E) None of the above. D) B and C. - correct answer Fatty acids are the building blocks of A) cholesterol. B) phospholipids. C) glycolipids. D) B and C. E) A, B, and C. C) lipases. - correct answer Enzymes that digest the triacylglycerols into free fatty acids and monoacylglycerol are called A) hydrases. B) glyases. C) lipases. D) All of the above. E) None of the above. B) glucagon; insulin - correct answer The hormone __________ induces lipolysis, whereas the hormone __________ inhibits the process. A) epinephrine; adrenocorticotropic hormone B) glucagon; insulin C) insulin; norepinephrine D) glucagon; epinephrine E) epinephrine; glucagon C) ATP-dependent activation of fatty acids using CoA. - correct answer The enzyme acyl CoA synthetase catalyzes A) lipolysis to release free glyceraldehyde. B) ATP-dependent reduction prior to activation. C) ATP-dependent activation of fatty acids using CoA. D) All of the above. E) None of the above. C) 7 acetyl CoA + 6 FADH2 + 6 NADH + 6 H+. - correct answer The b oxidation of myristyl-CoA (14:0) yields A) 7 acetyl CoA + 7 FADH2 + 7 NADH + 7 H+. B) 6 acetyl CoA + 7 FADH2 + 7 NADH + 7 H+. C) 7 acetyl CoA + 6 FADH2 + 6 NADH + 6 H+. D) 7 acetyl CoA + 7 FAD + 7 NAD+. E) 14 acetyl CoA + 12 FADH2 + 12 NADH + 12 H+. C) 7 - correct answer How many rounds of b oxidation would be required for a 16-carbon fatty acyl chain to be degraded to acetyl CoA? A) 16 B) 8 C) 7 D) 15 E) None of the above. D) A and B - correct answer Which organs or tissues prefer to use ketone bodies such as acetoacetate as a fuel energy source instead of glucose? A) the heart muscle B) the renal cortex C) the brain D) A and B E) A, B, and C D) All of the above. - correct answer Triacylglycerol stored in adipose tissue is used by the liver and other tissues for A) glycerol for pyruvate and glucose in liver. B) ATP production via the citric acid cycle in muscle. C) conversion to acetyl CoA and ketone bodies during starvation for the brain. D) All of the above. E) None of the above. B) three acetyl CoA molecules. - correct answer Three rounds of fatty acid oxidation result in A) two acetyl CoA molecules. B) three acetyl CoA molecules. C) the synthesis of palmitate. D) the formation of enoyl CoA. E) the complete oxidation of palmitate B. B) Acyl adenlyate; only the activated form of the fatty acid can react with coenzyme A. - correct answer The activation of fatty acids for degradation takes place in two steps. What is the intermediate formed and why is activation necessary for β oxidation to occur? A) Acyl adenlyate; the cAMP formed by this reaction activates protein kinase A. B) Acyl adenlyate; only the activated form of the fatty acid can react with coenzyme A. C) Propionate; only the activated form of the fatty acid can react with coenzyme A. D) Acyl carnitine; the cAMP formed by this reaction activates protein kinase A. E) Acyl carnitine: this intermediate is needed to fuel the carnitine cycle. D) A and B. - correct answer Membrane lipids are primarily comprised of: A) phospholipids. B) glycolipids. C) cholesterol. D) A and B. E) A, B, and C. C) structural rigidity of the cytoskeleton - correct answer Which of the following is NOT a main function of lipids? A) cell signalling B) fuel source C) structural rigidity of the cytoskeleton D) membrane component E) All of the above. D) 3 - correct answer Octadecatrienoic acid has how many double bonds? A) 0 B) 1 C) 2 D) 3 E) 4 E) None of the above. - correct answer An w-3 fatty acid ____________. A) has a methyl group at the carboxyl end of the fatty acid B) has a methyl group on the third carbon of the chain C) has a double bond the third carbon in from the carboxyl group D) has a triple bond on the third carbon from the methyl end of the fatty acid E) None of the above. A) There are 12 carbons in the chain with two double bonds. - correct answer The notation 12:2 indicates which of the following about a fatty acid? A) There are 12 carbons in the chain with two double bonds. B) There are two 12-carbon chains for this fatty acid. C) The second carbon has a fatty acid double bond. D) The 12th carbon has a double bond. E) There are two trans-double bonds on this 12-carbon fatty acid. C) higher the melting point of - correct answer The longer the fatty acid the ________ the fatty acid. A) more oxidized B) lower the melting point of C) higher the melting point of D) more reduced E) more double-bond containing B) decrease - correct answer Unsaturation ________ melting points of fatty acids and their derivatives. A) maintain B) decrease C) increase D) are unrelated to E) None of the above. C) fatty fish, cardiovascular disease - correct answer Eating ____________ increases the w-3 fatty acids decreasing ___________. A) arachidonic acid, cardiovascular disease B) a low fat diet, cardiovascular disease C) fatty fish, cardiovascular disease D) shellfish, lung cancer E) vegetable oils, blood pressure E) glycerol - correct answer The backbone of a phospholipid is which of the following? A) glucose B) cholesterol C) fatty acid chain D) triacylglycerol E) glycerol C) C3 - correct answer The polar head group of phospholipids is found at which carbon of glycerol? A) C1 B) C2 C) C3 D) C1-OH E) C2-OH E) Cholesterol is esterified to a fatty acid for transport by lipoprotein particles, the surface of which is hydrophilic and the interior is hydrophobic. - correct answer Cholesterol and other steroids are not soluble in blood, and therefore must be transported. Predict what chemical modifications must occur for cholesterol to move through the circulatory system. A) Cholesterol forms micells in blood, the surface of which is hydrophilic and the interior is hydrophobic. B) Cholesterol cannot be transported in blood and so it broken down and resynthesized in all cells. C) Cholesterol moves through cell membranes from tissue to tissue. D) Cholesterol forms glycolipids with large carbohydrate complexes in order to increase solubility. E) Cholesterol is esterified to a fatty acid for transport by lipoprotein particles, the surface of which is hydrophilic and the interior is hydrophobic. A) 3-hydroxy-3-methylglutaryl (HMG) CoA reductase. - correct answer Feedback regulation of cholesterol synthesis is mainly controlled at the step catalyzed by the enzyme A) 3-hydroxy-3-methylglutaryl (HMG) CoA reductase. B) geranyl transferase. C) HMG transferase. D) farnesyl reductase. E) None of the above. E) A and C. - correct answer The role of lipoprotein particles is to A) solubilize hydrophobic lipids. B) aid in clot formation. C) contain cell-targeting signals. D) A and B. E) A and C. B) chylomicrons. - correct answer The major carrier(s) of dietary fat from the intestine is(are) A) VLDL. B) chylomicrons. C) HDL. D) LDL. E) IDL. A) clathrin - correct answer The LDL receptors on the plasma membrane are localized in coated pits that contain the receptors of which of the following proteins? A) clathrin B) lipoprotein A C) adrenodoxin D) HMG-CoA reductase E) sterol regulatory element binding protein (SREBP) E) No, some cholesterol synthesis is essential. Cholesterol is essential for proper functioning of cell membranes and for precursors for bile salts and steroid hormones. - correct answer Your grandfather has been told he has high cholesterol and has been given one of the statins to bring it down. He asks you if you can think of any reason that he should not double the dose so that it will reduce blood cholesterol faster. What do you tell him? A) Yes, statins block the reabsorption of bile, effectively blocking the absorption of cholesterol. B) Yes, statins decrease the amount of LDL receptors on the surface of intestinal mucosal cells, thereby decreasing cholesterol uptake into the blood. C) Yes, statins increase the amount of LDL receptors on the surface of blood vessels increasing the internalization of cholesterol into cells and clearing the blood. D) No, at high levels, statins have a stimulatory effect on HMG-CoA reductase rather than inhibitory effect. E) No, some cholesterol synthesis is essential. Cholesterol is essential for proper functioning of cell membranes and for precursors for bile salts and steroid hormones. B) Sunlight is necessary for the conversion of cholesterol to vitamin D, a hormone necessary for bone health. - correct answer You are prone to sunburn, but you doctor tells you not to apply your sunscreen until you have been outside for five minutes. Why? A) Sunscreen blocks UV radiation necessary for cholesterol synthesis in the skin where it is converted to vitamin D. B) Sunlight is necessary for the conversion of cholesterol to vitamin D, a hormone necessary for bone health. C) Skin pigmentation, as occurs when you get a light tan, blocks UV radiation and reduces the incidence of skin cancers. D) Vitamin D in the skin blocks UV radiation, but only for a short period of time; thus, it is a natural sun block. E) Sunlight promotes HDL mobilization and a clearing of cholesterol in the blood.