Final Exam Biochemistry Fall 2005
47 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

How do a nucleotide and a nucleoside differ?

  • A nucleoside is found in DNA, whereas nucleotides are found in RNA.
  • Nucleosides contain only deoxyribose sugars.
  • A nucleotide is a nucleoside with a phosphate ester linked at the sugar 5' residue. (correct)
  • Purines are only found in nucleotides.

    • What is the difference in RNA bases compared to DNA bases?

  • U instead of G.
  • A instead of U.
  • U instead of T. (correct)
  • A instead of T.

    • What is the most abundant type of RNA found in the cell?

  • rRNA. (correct)
  • mRNA.
  • tRNA.
  • snRNA.

    • Which is the smallest RNA molecule?

    <p>tRNA.</p> Signup and view all the answers

    Why is the peptide bond planar?

    <p>It contains partial double bond character, preventing rotation.</p> Signup and view all the answers

    The neurotransmitter serotonin is synthesized from which amino acid?

    <p>tryptophan.</p> Signup and view all the answers

    Which amino acids contain reactive aliphatic hydroxyl groups?

    <p>serine and threonine.</p> Signup and view all the answers

    What determines a protein’s function?

    <p>all of the above.</p> Signup and view all the answers

    In the malate-aspartate shuttle, the electrons from NADH are transferred to which compound to form malate?

    <p>oxaloacetate</p> Signup and view all the answers

    What is the net estimate of ATP molecules produced from the oxidation of glucose when using the malate-aspartate shuttle?

    <p>30</p> Signup and view all the answers

    Which molecule is known as the currency of reducing power?

    <p>NADPH</p> Signup and view all the answers

    Which of the following reactions does NOT occur in the pentose phosphate pathway?

    <p>C5 + C6 → C2 + C9</p> Signup and view all the answers

    What is the major site of glycogen storage in the human body?

    <p>both b and c</p> Signup and view all the answers

    Which enzyme is key in glycogen degradation?

    <p>glycogen phosphorylase</p> Signup and view all the answers

    After a carbohydrate-rich meal, what happens to blood-glucose levels?

    <p>They rise, leading to glycogen storage</p> Signup and view all the answers

    What molecule initiates the TCA cycle by reacting with oxaloacetate?

    <p>Acetyl CoA</p> Signup and view all the answers

    Which enzyme is responsible for the conversion of pyruvate to acetyl CoA?

    <p>Pyruvate dehydrogenase</p> Signup and view all the answers

    Which enzymes catalyze the control point reactions of the TCA cycle in mammals?

    <p>Isocitrate dehydrogenase and alpha-ketoglutarate dehydrogenase</p> Signup and view all the answers

    What is the approximate yield of ATP produced per NADH during oxidative phosphorylation?

    <p>2.5 ATP per NADH</p> Signup and view all the answers

    How many ATP or GTP equivalents are generated during one turn of the citric acid cycle?

    <p>10</p> Signup and view all the answers

    What type of ion gradient is critical for ATP formation during oxidative phosphorylation?

    <p>Proton</p> Signup and view all the answers

    Which of the following does not shuttle electrons in the electron transport chain?

    <p>Complex II</p> Signup and view all the answers

    What is the net ATP obtained per NADH when the glycerol 3-phosphate shuttle is used?

    <p>1.5</p> Signup and view all the answers

    What type of enzyme digests triacylglycerols into free fatty acids and monoacylglycerol?

    <p>Lipases</p> Signup and view all the answers

    Which hormone is known to inhibit the process of lipolysis?

    <p>Insulin</p> Signup and view all the answers

    How many rounds of beta-oxidation are needed for a fatty acid with a 16-carbon acyl chain?

    <p>7</p> Signup and view all the answers

    What is the primary function of acyl CoA synthetase?

    <p>Activating fatty acids</p> Signup and view all the answers

    Which intermediate is involved in fatty acid synthesis?

    <p>Acyl carrier protein</p> Signup and view all the answers

    What is the committed step during fatty acid synthesis?

    <p>Synthesis of malonyl CoA</p> Signup and view all the answers

    What molecule serves as the carrier for urea synthesis in the urea cycle?

    <p>Ornithine</p> Signup and view all the answers

    Which of the following amino acids can directly supply amino groups for conversion to NH4+?

    <p>Serine, Asparagine, and Threonine</p> Signup and view all the answers

    What are the sources of the two nitrogen atoms in urea?

    <p>ammonia and aspartate</p> Signup and view all the answers

    Amino acids that are degraded to acetyl CoA are classified as which type of amino acids?

    <p>ketogenic</p> Signup and view all the answers

    Which of the following statements about Vitamin B12 is correct?

    <p>It converts homocysteine to methionine.</p> Signup and view all the answers

    Why might taking vitamin B12 supplements be ineffective for most individuals?

    <p>Defective absorption typically leads to deficiency.</p> Signup and view all the answers

    What is the primary preventive strategy for individuals with phenylketonuria?

    <p>Elimination of phenylalanine from the diet.</p> Signup and view all the answers

    Glutamine synthetase catalyzes the addition of NH3 to which compound to produce glutamine?

    <p>glutamate</p> Signup and view all the answers

    Glutamate serves as a precursor for which amino acids?

    <p>glutathione and proline</p> Signup and view all the answers

    Which type of units can tetrahydrofolate carry?

    <p>Methyl, methylene, and formyl groups</p> Signup and view all the answers

    Which enzyme is responsible for converting nucleoside diphosphates to nucleoside triphosphates?

    <p>nucleoside diphosphate kinase</p> Signup and view all the answers

    Which nitrogen source is required for the synthesis of CTP from UTP?

    <p>glutamine and ATP</p> Signup and view all the answers

    What reductant is used by dihydrofolate reductase to generate tetrahydrofolate from dihydrofolate?

    <p>NADPH</p> Signup and view all the answers

    Fluorouracil and aminopterin are known to primarily reduce the level of which nucleotide?

    <p>dTMP</p> Signup and view all the answers

    What is the principal enzyme inhibited by allopurinol?

    <p>xanthine oxidase</p> Signup and view all the answers

    What is the first compound formed in the pathway leading to phospholipids and triacylglycerols?

    <p>phosphatidate</p> Signup and view all the answers

    Tay Sachs disease is primarily characterized by an inability to degrade which lipids?

    <p>gangliosides</p> Signup and view all the answers

    Which step is primarily controlled in the feedback regulation of cholesterol synthesis?

    <p>3-hydroxy-3-methylglutaryl CoA reductase</p> Signup and view all the answers

    Study Notes

    Final Exam, Biochemistry, Fall 2005

    • Multiple Choice Questions - Nucleotides and Nucleic Acids

      • Nucleotides differ from nucleosides by having a phosphate ester linked to the sugar 5' residue.
      • RNA nucleotides differ from DNA nucleotides by containing uracil (U) instead of thymine (T).
      • The most abundant type of RNA in the cell is rRNA.
      • The smallest RNA molecule is tRNA.

    • Multiple Choice Questions - Proteins and Peptides

      • Peptide bonds are planar due to partial double bond character, preventing rotation around the bond.
      • Serine and threonine contain reactive aliphatic hydroxyl groups.
      • Protein function is determined by its structure.
      • Serotonin is synthesized from tryptophan.

    • Multiple Choice Questions - Enzymes

      • The formula log K'eq = ∆G°/1.36 relates the free energy and the equilibrium constant.
      • The common strategy for catalysis is increasing the probability of product formation.
      • Enzyme catalysts can be RNA and proteins.
      • Km is equal to the substrate concentration when the reaction rate is half its maximal value.
      • The Gibbs free energy of activation is the difference between the substrate and the transition state.
      • Nicotinic acid is necessary for one carbon transfer, methyl group transfer, and oxidation-reduction reactions.
      • His, Ser, Asp are amino acids in chymotrypsin involved in substrate cleavage.

    • Multiple Choice Questions - Carbohydrates

      • Glycogen is the main storage form of glucose in mammals.
      • 2 molecules thick membranes.
      • Cholesterol helps regulate membrane fluidity.

    • Multiple Choice Questions - Metabolism

      • Major purposes for energy are mechanical work, active transport, and synthesis of biomolecules.
      • Reaction pathways that transform fuels into cellular energy are anabolic and catabolic.
      • Free energy change for ATP hydrolysis to ADP is 30.5 kJ/mol.
      • Fats are more efficient energy sources than carbs because they are more oxidized.
      • An example of oxidation is conversion of succinate to fumarate using FAD.
      • Examples of enzymatic reactions that are isomerizations include conversion of citrate to isocitrate.
      • Enzyme catalysts can be RNA and proteins.
      • Km is equal to the substrate concentration when the reaction rate is half its maximal value.

    • Multiple Choice Questions - Glycolysis & Gluconeogenesis

      • The committed step in glycolysis – and the most important control point – is catalyzed by phosphofructokinase.
      • The cleavage of fructose-1,6-bisphosphate generates glyceraldehyde-3-phosphate and dihydroxyacetone phosphate.
      • Pyruvate kinase activity is regulated by alanine, fructose 1,6 bisphosphate and phosphoenolpyruvate.
      • Primary raw materials for gluconeogenesis are lactate and alanine.

    • Multiple Choice Questions - The Citric Acid Cycle

      • Key control point reactions in the TCA cycle are catalyzed by pyruvate dehydrogenase complex, isocitrate dehydrogenase and α-ketoglutarate dehydrogenase complex.
      • 10 ATP or GTP equivalents are made during one turn of the citric acid cycle.
      • α-ketoglutarate, Succinyl CoA and citrate are biosynthetic precursors of the citric acid cycle.

    • Multiple Choice Questions - Oxidative Phosphorylation

      • The critical gradient for ATP formation in oxidative phosphorylation is the proton gradient.
      • Oxidative phosphorylation converts the electron transfer potential of NADH and FADH2 to phosphoryl transfer potential of ATP.
      • Electron flow in the electron transport chain leads to proton transport across the inner mitochondrial membrane.
      • Net ATP produced per NADH using glycerol-3-phosphate shuttle is 1.5 ATP.
      • In malate-aspartate shuttle, electrons from NADH are transferred to oxaloacetate.

    • Multiple Choice Questions - Pentose Phosphate Pathway

      • The pentose phosphate pathway is for generating NADPH and 5-carbon sugars.
      • Not part of pentose phosphate pathway include reactions with C5+C5 → C3+C7 or C3+C7 → C6+C4.

    • Multiple Choice Questions - Glycogen Metabolism

      • Glycogen is primarily stored in the liver and skeletal muscle.
      • The key enzyme in glycogen degradation is glycogen phosphorylase.

    • Multiple Choice Questions - Fatty Acid Metabolism

      • Fatty acids are the building blocks of cholesterol, phospholipids, glycolipids.
      • The process of converting glucose 1-phosphate to glucose 6-phosphate is carried out by phosphoglucomutase.
      • Key regulatory enzyme in glycogen synthesis is glycogen synthase.
      • Fatty acid degradation occurs in mitochondria.
      • 8 rounds of β-oxidation are required for a 16-carbon fatty acid chain to produce acetyl CoA.

    • Multiple Choice Questions - Protein Turnover & Amino Acid Catabolism

      • Surplus amino acids are stored in proteosomes, protein scaffolds, and used as metabolic fuel.
      • Serine, asparagine and threonine are amino acids that supply amino groups that can be converted to NH4+.

    • Multiple Choice Questions - Amino Acid Biosynthesis

      • Glutamine synthetase adds NH3 to glutamate to synthesize glutamine.
      • Types of units carried by tetrahydrofolate are CO2, methyl, methylene and formyl groups
      • Amino acid precursors for nucleotide synthesis are glycine, glutamine, and aspartate.
      • Tetrahydrofolate is generated from dihydrofolate through dihydrofolate reductase.

    • Multiple Choice Questions - Nucleic Acid Biosynthesis

      • Sources of NH2 in nucleotide synthesis: aspartate, glutamine and glycine.
      • Scaffolds for ring systems in nucleotides: glycine, glutamine and aspartate.
      • Components used in pyrimidine synthesis: bicarbonate, aspartate and glutamine.
      • Nucleoside triphosphate kinase is an enzyme that carries out XDP + YTP → XTP + YDP reaction.
      • CTP is synthesized from UTP along with glutamine and ATP.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    2005 Biochemistry Final Exam PDF

    Description

    Test your knowledge on key biochemistry concepts including nucleotides, proteins, and enzyme functions. This quiz includes multiple-choice questions designed to challenge your understanding of molecular biology from the Fall 2005 semester.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser