Biochemistry Exam 1

22 Questions

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Biochemistry Exam Quizzes & Trivia

Biochemistry Exam 1


Questions and Answers
  • 1. 
    A weak acid can act as a buffer......
    • A. 

      At pH values=pK±0.1

    • B. 

      At pH values = pK ± 1

    • C. 

      At pH values = pK ± 2

    • D. 

      Only at body temperatures

    • E. 

      None of the above

  • 2. 
    Which of the following is considered to be a fibrous protein?
    • A. 

      Hemoglobin

    • B. 

      Immunoglobulin

    • C. 

      Keratin

    • D. 

      Myoglobin

    • E. 

      None of the above

  • 3. 
    Disulfide bonds most often stabilize the native structure of:
    • A. 

      Dimeric proteins

    • B. 

      Extracellular proteins

    • C. 

      Hydrophobic proteins

    • D. 

      Intracellular proteins

    • E. 

      All of the above

  • 4. 
    In sickle cell anemia, the basis of the malfunction of the hemoglobin molecule is:
    • A. 

      Faulty binding of the heme groups

    • B. 

      Incorrect secondary structure

    • C. 

      Reduced affinity for oxygen

    • D. 

      Substitution of a single amino acid

    • E. 

      None of the above

  • 5. 
    When BPG (2,3-Bisphosphoglycerate) binds to ______ site(s) on hemoglobin ________ its affinity for O2
    • A. 

      Four/decreases

    • B. 

      Four/increases

    • C. 

      One/decreases

    • D. 

      One/increases

    • E. 

      None of the above

  • 6. 
    The complementarity-determining regions (CDRs)
    • A. 

      Are found at the antigen-binding sites

    • B. 

      Reside in the VL and VH regions of the IgG molecule

    • C. 

      Reside in the CL and CH regions of the IgG molecule

    • D. 

      A and B are correct

    • E. 

      A and C are correct

  • 7. 
    Antibodies of the IgG class
    • A. 

      Consist of four subunits

    • B. 

      Are glycoproteins

    • C. 

      Have inter- and intra-chain disulfide crosslinks

    • D. 

      All three choices are correct

    • E. 

      None of the choices are correct

  • 8. 
    The two exonuclease activities of DNA polymerase I
    • A. 

      Are coupled during the formation of "gapped DNA"

    • B. 

      Degrade DNA in a 3' --> 5' direction

    • C. 

      Degrade DNA in a 5' --> 3' direction

    • D. 

      Occur at two different active sites

    • E. 

      None of the above

  • 9. 
    The RNA primers used to initiate replication in E. coli
    • A. 

      Are joined together by DNA ligase

    • B. 

      Are removed by helicase + ATP

    • C. 

      Are removed by Pol I "nick translation

    • D. 

      Result in Okazaki fragments on the leading strand

    • E. 

      None of the above

  • 10. 
    On the ribosome, mRNA binds ____; the peptidyl transferase reaction occurs ____
    • A. 

      Between the subunits; on the large subunit

    • B. 

      Between the subunits; on the small subunit

    • C. 

      To the large subunit; on the small subunit

    • D. 

      To the small subunit; on the large subunit

    • E. 

      None of the above

  • 11. 
    The pKa of an ionizable side chain, such as imidazole in histidine, can be determined with NMR because
    • A. 

      Protonated imidazole has twice the number of protons

    • B. 

      The chemical shift of His differs from that of His+

    • C. 

      The pKa is near neutrality

    • D. 

      Unprotonated imidazole is invisible in the spectrum

    • E. 

      None of the above

  • 12. 
    During the synthesis of a 100 residue protein, the number of GTP molecules used during initiation, elongation, and termination are, respectively:
    • A. 

      1, 100, 1

    • B. 

      1, 198, 1

    • C. 

      1, 200, 1

    • D. 

      2, 198, 2

    • E. 

      None of the above

  • 13. 
    Peripheral membrane proteins
    • A. 

      Are not accommodated by the fluid mosaic model

    • B. 

      Are only of peripheral interest to membrane biologists

    • C. 

      Can be dissociated from membranes relatively easily, e.g., high salt treatment

    • D. 

      Can undergo transverse membrane motion, i.e. "flip-flop"

    • E. 

      None of the above

  • 14. 
    During glycolysis the following reaction requires NAD+:
    • A. 

      Alcohol dehydrogenase

    • B. 

      Glyceraldehyde-3-phosphate dehydrogenase

    • C. 

      Lactate dehydrogenase

    • D. 

      Pyruvate dehydrogenase

    • E. 

      All of the above

  • 15. 
    Since the energy released by all the reactions of glycolysis is 185 kJ/mol glucose, and ____ mol ATP is/are produced per mol glucose, the overall efficiency of glycolysis is about ____
    • A. 

      1/ 16%

    • B. 

      1 /33%

    • C. 

      2 /33%

    • D. 

      2 /50%

    • E. 

      None of the above

  • 16. 
    Glycogen digestion in the gut begins with a ________ reaction; intracellular glycogen breakdown begins with a ________ reaction.
    • A. 

      Hydrolysis; hydrolysis

    • B. 

      Hydrolysis; phosphorolysis

    • C. 

      Hydrolysis; phosphorylation

    • D. 

      Phosphorolysis; hydrolysis

    • E. 

      None of the above

  • 17. 
    The correct order, from fastest-acting to slowest, for the time scale of these regulatory mechanisms is:
    • A. 

      Allosteric - covalent - genetic

    • B. 

      Allosteric - genetic - covalent

    • C. 

      Covalent - genetic - allosteric

    • D. 

      Genetic - allosteric - covalent

    • E. 

      None of the above

  • 18. 
    Mitochondrial ATP synthesis requires
    • A. 

      A [H+] gradient

    • B. 

      A membrane potential

    • C. 

      An intact inner mitochondrial membrane

    • D. 

      All of the above

    • E. 

      None of the above

  • 19. 
    Which of the following enzymes does not catalyze a physiologically irreversible step in glycolysis?
    • A. 

      Hexokinase

    • B. 

      Phosphofructokinase

    • C. 

      Phosphoglycerate kinase

    • D. 

      Pyruvate kinase

    • E. 

      None of the above

  • 20. 
    Following the addition of a mitochondrial respiratory inhibitor, components of the electron transport chain
    • A. 

      All components will be oxidized

    • B. 

      Downstream of the blockage will be reduced

    • C. 

      Upstream of the blockage will be oxidized

    • D. 

      Upstream of the blockage will be reduced

    • E. 

      None of the above

  • 21. 
    • A. 

      2 Cyt c (Fe2+); [FADH2]

    • B. 

      [FAD]; [FADH2]

    • C. 

      2 Cyt c (Fe2+); 2 Cyt c (Fe3+)

    • D. 

      [FAD]; 2 Cyt c (Fe3+)

    • E. 

      None of the above

  • 22. 
    Acetyl groups (e.g. for lipid biosynthesis) are transported out of the mitochondria indirectly using
    • A. 

      Acetyl carnitine

    • B. 

      Acetyl phosphate

    • C. 

      Citrate

    • D. 

      Malate

    • E. 

      All of the above