Prelim 4 Review
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Questions and Answers

What is the primary difference between the polar head group of phospholipids and glycolipids?

  • The presence of fatty acids in phospholipids
  • The type of linkage between the head group and the backbone (correct)
  • The number of glycerol molecules in the backbone
  • The presence of a phosphate group in glycolipids

    • What is the parent compound of glycerophospholipids?

  • Phosphatidic acid (correct)
  • Phosphatidylcholine
  • Sphingosine
  • Glycerol

    • What is the characteristic of the acyl chains in glycerophospholipids?

  • Non-polar (correct)
  • Polar
  • Hydrophobic
  • Hydrophilic

    • What determines the surface properties of membranes in glycerophospholipids?

    <p>The properties of the head group (D)</p> Signup and view all the answers

    What is the characteristic of the head group in glycerophospholipids?

    <p>Polar (C)</p> Signup and view all the answers

    What is the unique feature of cardiolipin among glycerophospholipids?

    <p>It has two phosphatidic acids sharing a single glycerol (D)</p> Signup and view all the answers

    What is the primary function of bile acids in the intestine?

    <p>To emulsify dietary fats and make them more accessible to lipases (C)</p> Signup and view all the answers

    What is the role of cholesterol in the plasma membrane of eukaryotic cells?

    <p>To thicken the plasma membrane and reduce its fluidity (C)</p> Signup and view all the answers

    What is the primary source of cholesterol for mammals?

    <p>Food and de novo synthesis in the liver (A)</p> Signup and view all the answers

    What is the role of eicosanoids in the body?

    <p>To act as signaling molecules between nearby cells (D)</p> Signup and view all the answers

    What is the effect of nonsteroidal anti-inflammatory drugs (NSAIDs) on the production of prostaglandins and thromboxanes?

    <p>They inhibit the production of prostaglandins and thromboxanes (A)</p> Signup and view all the answers

    What is the function of prostaglandins, thromboxanes, and leukotrienes in the body?

    <p>To mediate inflammation, vasoconstriction, and platelet aggregation (A)</p> Signup and view all the answers

    What is the primary location where fatty acids are converted to TAGs or enter gluconeogenesis?

    <p>Liver (D)</p> Signup and view all the answers

    What is the minimum number of carbon atoms required for fatty acids to be transported via the acyl-carnitine/carnitine transporter?

    <p>12 (B)</p> Signup and view all the answers

    What is the total energy equivalent used in the conversion of a fatty acid to a fatty acyl-CoA?

    <p>2 ATP equivalents (C)</p> Signup and view all the answers

    What is the enzyme responsible for catalyzing the conversion of a fatty acid to a fatty acyl-CoA?

    <p>Fatty acyl-CoA synthetase (A)</p> Signup and view all the answers

    What is the purpose of the carnitine shuttle in fatty acid transport?

    <p>To transport fatty acids across the mitochondrial membrane (D)</p> Signup and view all the answers

    What is the byproduct of the conversion of a fatty acid to a fatty acyl-CoA, in addition to FA-CoA and AMP?

    <p>PPi (B)</p> Signup and view all the answers

    What is the total number of acetyl-CoA molecules formed after passing through the pathway?

    <p>Eight (A)</p> Signup and view all the answers

    Which enzyme is responsible for catalyzing the dehydrogenation of alkane to alkene?

    <p>Acyl-CoA Dehydrogenase (B)</p> Signup and view all the answers

    What is the result of the dehydrogenation reaction catalyzed by Acyl-CoA Dehydrogenase?

    <p>Formation of a trans double bond (D)</p> Signup and view all the answers

    What is the purpose of the Electron-Transferring Flavoprotein (ETF) in the electron transport chain?

    <p>To transfer electrons from FAD to the electron transport chain (B)</p> Signup and view all the answers

    What is the genetic defect that leads to Medium-Chain Acyl-CoA Dehydrogenase (MCAD) deficiency?

    <p>Recessive mutation in Medium-Chain Acyl-CoA Dehydrogenase (C)</p> Signup and view all the answers

    What is the consequence of MCAD deficiency in terms of energy metabolism?

    <p>Cells rely on glucose for energy (C)</p> Signup and view all the answers

    Which enzyme is responsible for transferring electrons from acyl-CoA dehydrogenase to ubiquinone?

    <p>ETF: ubiquinone oxidoreductase (D)</p> Signup and view all the answers

    What is the result of the reaction catalyzed by enoyl-CoA hydratase?

    <p>Addition of water across the double bond (D)</p> Signup and view all the answers

    Which coenzyme is used as the hydride acceptor in the reaction catalyzed by β-hydroxyacyl-CoA dehydrogenase?

    <p>NAD+ (C)</p> Signup and view all the answers

    What is the net result of the thiolase reaction in the β oxidation process?

    <p>Thiolysis of a carbon-carbon bond (A)</p> Signup and view all the answers

    How many molecules of acetyl-CoA are produced from the complete β oxidation of one molecule of palmitoyl-CoA?

    <p>8 (B)</p> Signup and view all the answers

    What is the role of the enzyme acyl-CoA acetyltransferase (thiolase) in the β oxidation process?

    <p>To catalyze the thiolysis of a carbon-carbon bond (B)</p> Signup and view all the answers

    Which of the following fatty acids is a C18 mono-unsaturated fatty acid with a double bond at the 9th carbon?

    <p>Oleic acid (C)</p> Signup and view all the answers

    What is the designation of the carbon at the end of the fatty acid chain in the alternative convention for naming polyunsaturated fatty acids?

    <p>ω (C)</p> Signup and view all the answers

    Which of the following fatty acids can be synthesized from Alpha Linolenic Acid (ALA)?

    <p>Both Eicosa Pentanoic Acid (EPA) and Docosa Hexanoic Acid (DHA) (A)</p> Signup and view all the answers

    What is the number of carbon atoms in Palmitoleic acid, a C16 mono-unsaturated fatty acid?

    <p>16 (A)</p> Signup and view all the answers

    Which of the following is NOT an omega-3 fatty acid?

    <p>Oleic acid (A)</p> Signup and view all the answers

    What is the notation for Palmitic acid, a C16 saturated fatty acid, in the standard convention for naming fatty acids?

    <p>16:0 (B)</p> Signup and view all the answers

    What is the result of the photochemical reactions that occur when a rhodopsin molecule is excited by visible light?

    <p>Conversion of 11-cis-retinal to all-trans-retinal (C)</p> Signup and view all the answers

    What is the primary function of vitamin E in the body?

    <p>Removal of free radicals (B)</p> Signup and view all the answers

    What is the role of ubiquinone in the body?

    <p>Part of the electron transport chain (B)</p> Signup and view all the answers

    What is the function of dolichols in animals?

    <p>Unknown function (C)</p> Signup and view all the answers

    Where do the digestion and absorption of dietary lipids occur?

    <p>Small intestine (D)</p> Signup and view all the answers

    What is the result of the conversion of 11-cis-retinal to all-trans-retinal in rhodopsin?

    <p>Change in the shape of the entire rhodopsin molecule (D)</p> Signup and view all the answers

    What is the net energy cost of fatty acid synthesis in eukaryotes?

    <p>3 ATPs per 2-carbon unit (A)</p> Signup and view all the answers

    What is the role of citrate in fatty acid synthesis?

    <p>It activates acetyl-CoA carboxylase (D)</p> Signup and view all the answers

    What is the product of the condensation reaction in fatty acid synthesis?

    <p>Palmitate (D)</p> Signup and view all the answers

    What is the feedback inhibitor of acetyl-CoA carboxylase?

    <p>Palmitoyl-CoA (B)</p> Signup and view all the answers

    What is the purpose of the first step in fatty acid synthesis, where acetyl-CoA is converted to malonyl-CoA?

    <p>To commit acetyl-CoA to the fatty acid synthesis pathway (C)</p> Signup and view all the answers

    What is the energy equivalent of the reduced electron carriers generated in fatty acid synthesis?

    <p>14 NADPH (B)</p> Signup and view all the answers

    What is the cost of malonyl-CoA formation in terms of ATP molecules?

    <p>3 ATPs per 2-carbons unit (A)</p> Signup and view all the answers

    What is the role of biotin in the Acetyl-CoA Carboxylase (ACC) reaction?

    <p>To transport CO2 to the active site (C)</p> Signup and view all the answers

    What is the intermediate formed in the Acetyl-CoA Carboxylase (ACC) reaction?

    <p>Carboxyphosphate (C)</p> Signup and view all the answers

    What is the function of the transcarboxylase region in the Acetyl-CoA Carboxylase (ACC) enzyme?

    <p>To transfer activated CO2 to acetyl-CoA (C)</p> Signup and view all the answers

    How many functional regions does the Acetyl-CoA Carboxylase (ACC) enzyme have?

    <p>3 (A)</p> Signup and view all the answers

    What is the net result of the reaction catalyzed by Acetyl-CoA Carboxylase (ACC)?

    <p>Formation of malonyl-CoA (D)</p> Signup and view all the answers

    What is the mechanism by which free ammonia competes with K+ in astrocyte cells?

    <p>Through Na+-K+-2Cl- cotransporter 1 (NKCC1) (A)</p> Signup and view all the answers

    What is the source of the first amino group of urea in the urea cycle?

    <p>Free ammonia (D)</p> Signup and view all the answers

    What is the effect of elevated extracellular [K+] on neuronal response to the neurotransmitter GABA?

    <p>Altered response (C)</p> Signup and view all the answers

    What is the enzyme responsible for the first nitrogen-acquiring reaction of the urea cycle?

    <p>Carbamoyl phosphate synthase I (C)</p> Signup and view all the answers

    What is the fate of NH4+ liberated from the side chain of glutamine in the liver mitochondria?

    <p>Incorporated into urea (C)</p> Signup and view all the answers

    What is the ATP requirement for the first nitrogen-acquiring reaction of the urea cycle?

    <p>2 ATPs (D)</p> Signup and view all the answers

    What is the consequence of a deficiency in vitamin B12?

    <p>Both megaloblastic anemia and homocysteinemia and homocysteinuria (C)</p> Signup and view all the answers

    What is the role of N5,N10-methylene THF in DNA synthesis?

    <p>It is a necessary cofactor for the thymidylate synthase reaction (C)</p> Signup and view all the answers

    What is the result of the accumulation of homocysteine in the blood and urine?

    <p>Heart disease, hypertension, and stroke (D)</p> Signup and view all the answers

    Why is vitamin B12 necessary for the formation of methionine?

    <p>It is necessary for the methionine synthase reaction (D)</p> Signup and view all the answers

    What is the consequence of a deficiency in THF?

    <p>Megaloblastic anemia (D)</p> Signup and view all the answers

    What is the role of folates in the treatment of megaloblastic anemia?

    <p>It can partially treat the anemia (C)</p> Signup and view all the answers

    What is the oxidation state of the cofactor N5,N10-methylene H4folate?

    <p>Intermediate state (B)</p> Signup and view all the answers

    What is the primary source of one-carbon units for H4folate?

    <p>Conversion of serine to glycine (A)</p> Signup and view all the answers

    What is the limitation of H4folate in biosynthetic reactions?

    <p>Insufficient for transferring methyl groups (C)</p> Signup and view all the answers

    What is the role of S-adenosylmethionine in biosynthetic reactions?

    <p>To transfer methyl groups (B)</p> Signup and view all the answers

    What is the product of the conversion of serine to glycine in the folate cycle?

    <p>N5,N10-methylene H4folate (D)</p> Signup and view all the answers

    What is the primary function of S-adenosylmethionine in biological reactions?

    <p>Methyl transfer, with a methyl group 1000 times more reactive than THF methyl (D)</p> Signup and view all the answers

    What is the consequence of a folate deficiency in the body?

    <p>Folates are trapped in the N5-MTHF form (D)</p> Signup and view all the answers

    What is the role of methionine synthase in the folate cycle?

    <p>To regenerate THF from N5-MTHF (B)</p> Signup and view all the answers

    What is the source of carbon in the formation of tetrahydrofolate?

    <p>Serine (B)</p> Signup and view all the answers

    What is the intermediate formed in the conversion of formic acid to N5,N10-methenyl-H4folate?

    <p>N10-formyl H4folate (C)</p> Signup and view all the answers

    What is the role of biotin in the folate cycle?

    <p>Transferring CO2 (A)</p> Signup and view all the answers

    What is the consequence of folate deficiency in DNA synthesis?

    <p>Abnormal uracil incorporation into DNA (B)</p> Signup and view all the answers

    What is the target of fluorouracil, a chemotherapeutic agent?

    <p>Thymidylate synthase (C)</p> Signup and view all the answers

    What is the role of serine hydroxymethyltransferase in the folate cycle?

    <p>Synthesis of N5,N10-methylene THF (A)</p> Signup and view all the answers

    What is the primary function of reciprocal control in the synthesis of adenine and guanine nucleotides?

    <p>To balance the synthesis of AMP and GMP (B)</p> Signup and view all the answers

    What is the outcome of the reaction catalyzed by thymidylate synthase?

    <p>dUMP is converted to dTMP (C)</p> Signup and view all the answers

    What is the consequence of dihydrofolate reductase inhibition?

    <p>Reduced synthesis of dTMP (A)</p> Signup and view all the answers

    What is the committed step in the de novo synthesis of pyrimidine nucleotides?

    <p>The reaction between Asp and carbamoylphosphate, catalyzed by aspartate transcarbamoylase (D)</p> Signup and view all the answers

    What is the role of glutamine analogs, such as azaserine and acivicin, in chemotherapy?

    <p>Inhibition of glutamine amidotransferase (D)</p> Signup and view all the answers

    What is the committed step in purine synthesis?

    <p>Formation of 5-phosphoribosylamine (A)</p> Signup and view all the answers

    What is the role of ADP and GDP in the regulation of PRPP synthesis?

    <p>They inhibit the synthesis of PRPP (C)</p> Signup and view all the answers

    What is the precursor of the pyrimidine ring in de novo pyrimidine synthesis?

    <p>Carbamoylphosphate (C)</p> Signup and view all the answers

    What is the starting material for the synthesis of aspartate in humans?

    <p>Oxaloacetate (C)</p> Signup and view all the answers

    What is the enzyme responsible for the synthesis of carbamoylphosphate in pyrimidine synthesis?

    <p>Carbamoylphosphate synthase II (A)</p> Signup and view all the answers

    What is the effect of the excretion of large concentrations of homogentisate on urine?

    <p>It turns urine black (B)</p> Signup and view all the answers

    What is the role of glutamine in the synthesis of purines?

    <p>It donates a nitrogen atom (C)</p> Signup and view all the answers

    What is the fate of PRPP in mammals, apart from its use in pyrimidine synthesis?

    <p>It is used in the salvage pathway (D)</p> Signup and view all the answers

    What is the immediate precursor of inosine monophosphate (IMP) in purine synthesis?

    <p>5-Phosphoribosylamine (C)</p> Signup and view all the answers

    What is the net result of the synthesis of asparagine from aspartate in humans?

    <p>It releases one NH4+ molecule (C)</p> Signup and view all the answers

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