Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question. |
| ABCDE | 1. | The site of attenuation codes for: | a. | promoter region | d. | regulator gene | | b. | Operator gene | e. | None of the above | | c. | Leader region on messenger RNA |
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| ABCDE | 2. | For the lactose operon: | a. | The structural genes are continually being transcribed | d. | The structural genes are free to be transcribed when the inducer binds to the promoter site. | | b. | The structural genes are free to be transcribed when the inducer binds to the repressor. | e. | None of the above are true. | | c. | The structural genes are inhibited from transcription when the inducer binds to the repressor. |
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| ABCDE | 3. | As a co-repressor, tryptophan binds to the repressor and the complex then binds to: | a. | repressor gene | d. | promoter site | | b. | Cyclic AMP | e. | Operator site | | c. | Structural genes |
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| ABCDE | 4. | To allow for transcription, the inducer generally binds to: | a. | repressor | d. | Structural genes | | b. | operator site | e. | None of the above | | c. | promoter site |
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| ABCDE | 5. | For the arabinose operon, which if the choices below binds to cyclic AMP | a. | Arabinose | d. | arabinose and catabolyte Activator protein | | b. | Free repressor | e. | P2 form of repressor | | c. | Arabinose and repressor |
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| ABCDE | 6. | The complex of catabolyte Activator protein and cyclic AMP: | a. | Allows 'or transcription | d. | Prevents repressor from binding to operator site | | b. | prohibits transcription | e. | None of the above | | c. | Has no effect on allowing or prohibiting transcription |
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| ABCDE | 7. | For the tryptophan operon to be transcribed: | a. | An excess of tryptophan is required | d. | An excess phenylalanine is required | | b. | Low tryptophan levels are required | e. | "A" and "B" | | c. | Tryptophan concentration has no effect |
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| ABCD | 8. | For the lytic pathway, which must be in appreciable concentration: | a. | Cro protein | c. | Both | | b. | Lambda repressor | d. | Neither |
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| ABCDE | 9. | What makes up the lactose operon? | a. | Operator region | d. | Structural genes | | b. | Promoter region | e. | All of the above | | c. | Pribnow box |
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| ABCDE | 10. | The first step in incorporating an amino acid into a growing protein molecule involves: | a. | The formation of an ester bond between the amino acid carboxyl group and the 2'-hydroxyl group of transfer RNA | d. | The formation of an anhydride of the amino acid carboxyl group and the adenylic acid | | b. | The formation of a peptide bond between the amino acid carboxyl group and the N-terminal amino group of the growing peptide | e. | Transfer of the amino acid from the aminoacyl-CoA to transfer RNA.
| | c. | The expenditure of energy as GTP for the formation of an amino-acyl transfer RNA |
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| ABCDE | 11. | In an aminoacyl-transfer RNA, the aminoacyl moiety is attached to transfer RNA by: | a. | A high energy" phosphate bond | d. | An anhydride linkage | | b. | An ether linkage | e. | An amide linkage | | c. | An ester linkage |
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| ABCDE | 12. | Pseudouridine and dihydrouridine may be components of: | a. | Viral DNA | d. | Ribosomal RNA | | b. | Mammalian DNA | e. | Transfer RNA | | c. | Messenger RNA |
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| ABCDE | 13. | The synthesis of now DNA is more closely associated with the process of: | a. | Protein synthesis | d. | RNA synthesis | | b. | Cellular division | e. | Gene expression | | c. | Hybridization |
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| ABCDE | 14. | Histones:. | a. | Are identical to protamines | d. | Have relatively high molecular weights (200,000 and Above) | | b. | are covalently bound to DNA | e. | Cannot be dissociated from DNA except by prior digestion with nucleases | | c. | Are proteins rich in lysine and/or arginine |
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| ABCDE | 15. | Modification of this histone is necessary to "Loosen up" the nueleosome: |
| ABCDE | 16. | This is the most invariant of the histones: |
| ABCD | 17. | Polyamines are not involved in: | a. | Replication | c. | Translation | | b. | Stabilization of transfer RNA | d. | Formation of aminoacyl transfer RNA |
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| ABCDE | 18. | Which is not true concerning eu. (eukaryote) DNA polymerases: | a. | DNA polymerase alpha has a major role in replication | d. | Eukaryotic DNA polymerases have nuclease activity | | b. | DNA polymerase beta is for repair of nuclear DNA | e. | B and C
| | c. | DNA polymerase gamma is associated with mitochondrial activity |
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| ABCDE | 19. | Which is transcribed? | a. | Spacers between the repeating unit of clustered and tandemly arranged genes | d. | A and B | | b. | Introns | e. | B and C | | c. | Exons |
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| ABCD | 20. | Which are not included in the processed messenger RNA: | a. | Introns | c. | Both | | b. | Extrons | d. | Neither |
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| ABCDE | 21. | Diphtheria toxin acts by modifying | a. | An initiation factor | d. | A peptidyl transferase | | b. | An elongation factor | e. | None of the above | | c. | A termination factor |
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| ABCDE | 22. | Globin synthesis is inhibited by the phosphorylation of: | a. | 1F-1 | d. | e1F-2 | | b. | 1F-2 | e. | EF-2 | | c. | e1F-1 |
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K-QUESTIONS
DIRECTIONS: Answer:
A: if a, b, c are correct
B: if a, and c are correct
C: if b and d are correct
D: if only d is correct
E: if all are correct |
| ABCD | 23. | Modification of messenger RNA that occur after its synthesis on a template are: | a. | Addition of poly ADP-ribose | c. | Addition of CCA sequence to the 3' end | | b. | Transport across the nuclear membrane | d. | Removal of internal polynucleotide sequence |
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| ABCD | 24. | Besides having non-repetitive sequences that code for proteins in eukaryotes, DNA has which of the following other proteins? | a. | Palindromic sequences code for proteins | c. | Repetitive sequences code for proteins | | b. | Palindromic sequences may be sites that bind regulatory molecules | d. | repetitive sequences may have a structural or regulatory role |
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| ABCD | 25. | Histone I is associated with: | a. | Linker DNA | c. | Heterochromatin | | b. | Nucleosome | d. | Euchromatin |
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| ABCDE | 26. | biochemistry is associated with: | a. | Endless nights of study | d. | Joy of Understanding | | b. | Gallons of coffee | e. | All of the above | | c. | Hours of Despair |
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| ABCDE | 27. | The single most important method for the determination of polypeptide hormone levels is plasma is: | a. | Polyacrylamide GET electrophoresis | d. | Radioimmunoassay | | b. | Colorimetric assay with ninhydrin | e. | Edman degradation | | c. | High pressure liquid chromatography with electrochemical detection |
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| ABCDE | 28. | Growth factors whose release into the bloodstream is stimulated by growth hormone are called: | a. | Somatostatin | d. | Melatonin | | b. | Somatomammotropin | e. | Somatotropin | | c. | Somatomedins |
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| ABCDE | 29. | The active center of acetylcholinesterase contains an amino acid residue that forms a covalent bond with part of the substrate molecule. This amino acid is: | a. | Aspartate | d. | Arginine | | b. | Serine | e. | Lysine | | c. | Threonine |
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| ABCDE | 30. | Which of the following conditions causes a functional excess of acetylcholine in the synaptic cleft of the motor endplates? | a. | Botulism | d. | Organophosphorus poisoning | | b. | Cholera | e. | Myasthenia gravis | | c. | Diphtheria |
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| ABCDE | 31. | Which of the following conditions is caused by a toxin: | a. | Parkinson's disease | d. | Myasthenia gravis | | b. | Botulism | e. | B and C | | c. | Tetanus |
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| ABCDE | 32. | Choline acetyltransferase: | a. | Is synthesized in the nerve ending by ribosomes attached to synaptic vesicles. | d. | Is not present in cholinergic neurons, but only in cells which respond to acetylcholine | | b. | Inactivates acetylcholine in the synaptic cleft | e. | Synthesizes acetylcholine from choline and acetyl-CoA | | c. | Is irreversibly inhibited by organophosphorus compounds |
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| ABCDE | 33. | The release of neurotransmitters is always directly dependent on the presence of extracellular: | a. | Magnesium | d. | Sodium | | b. | Calcium | e. | Potassium | | c. | Chloride |
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| ABCDE | 34. | The high-affinity uptake of amino acid and amine neurotransmitters is directly dependent on the presence of extracellular: | a. | Magnesium | d. | Sodium | | b. | Calcium | e. | Potassium | | c. | Chloride |
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| ABCDE | 35. | The biosynthetic precursor of the neurotransmitter GABA (gamma-amino butyric acid) is: | a. | Glutamate | d. | Tryptophan | | b. | Aspartate | e. | Cysteine | | c. | Tyrosine |
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| ABCDE | 36. | The symptoms of tetanus (uncontrollable muscle spasms) are induced by: | a. | Reversible blockade of acetylcholine receptors | d. | Autoantibodies to the acetylcholine receptor | | b. | Increased permeability of the sodium channel in the axonal plasma membrane | e. | Irreversible inhibition of acetylcholinesterase | | c. | Blockade of inhibiting glycinergic neurotransmission in the spinal cord |
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| ABCDE | 37. | sodium channel of the axonal plasma membrane: | a. | Is open in the resting state and closes only during the action potential. | d. | Consumes ATP while transporting sodium out of the cell | | b. | Is inhibited by tetrodotoxin | e. | Is unaffected by extracellular calcium. | | c. | Is evenly distributed over the surface of myelinated axons, both on the myelinated segments and the nodes of Ranvier |
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| ABCDE | 38. | ATP formed in the mitochondrial matrix crosses: | a. | The inner mitochondrial membrane by passive diffusion, the outer membrane by facilitated diffusion | d. | The inner membrane, by proton cotransport, the outer membrane by passive diffusion. | | b. | The inner membrane by an antiport system ("facilitated exchange diffusion"), the outer membrane by passive diffusion. | e. | The inner membrane by passive diffusion, the outer membrane by sodium cotransport | | c. | The inner membrane by sodium cotransport, the outer membrane by passive diffusion. |
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| ABCDE | 39. | cotransport with sodium is the main mechanism for: | a. | the resorption of amino acids in the small intestine | d. | the transport of protons across the inner mitochondrial membrane | | b. | The resorption of glucose in the proximal tubule of the kidney | e. | A and D | | c. | Uptake of the iron-transferrin complex into the cell |
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| ABCDE | 40. | The glucose carrier in the erythrocyte membrane effects a net flow of glucose from the plasma into the erythrocyte because: | a. | It hydrolyzes ATP during glucose transport | d. | In the erythrocyte, glucose is converted to glucose-6-phosphate by hexokinase | | b. | Glucose is chemically modified during transport | e. | Glucose is transported into the cell together with a sodium ion | | c. | Glucose is transported into the cell together with calcium, which is subsequently removed by binding to calmodulin |
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| ABCDE | 41. | Which of the following is not necessary for the proper functioning of sodium-potassium ATPase? | a. | Phosphate in the extracellular space | d. | ATP in the intracellular space | | b. | Sodium in the intracellular space | e. | Magnesium in the intracellular space | | c. | Potassium in the extracellular space |
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| ABCDE | 42. | Which is true for cardiotonic steroids? | a. | they are rarely used in clinical practice | d. | They inhibit sodium-potassium ATPase by blocking its dephosphorylation | | b. | They are relatively non-toxic and can be used in very high doses without endangering the patient's life | e. | Their action is exclusively mediated by the sympathetic neurons innervating the heart | | c. | Calcium is not involved in their positive inotropic effect |
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| ABCDE | 43. | Passive diffusion is physiologically important for the uptake into the cell of: | a. | Glycoprotein hormone | d. | Oxygen | | b. | Norepinephrine | e. | Glucose | | c. | Peptide neurotransmitters |
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| ABCD | 44. | When the uptake of a substance across a biological membrane is both saturable and can be inhibited by a specific inhibitor, you can safely conclude that the transport is: | a. | Active (energy-requiring) | c. | Both | | b. | Carrier-mediated | d. | Neither |
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| ABCDE | 45. | Receptor mediated pinocytosis is physiologically important for the uptake into the cell of: | a. | Glycoprotein hormones | d. | Oxygen | | b. | Norepinephrine | e. | Glucose | | c. | Peptide neurotransmitters |
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| ABCDE | 46. | Which is not truce for sodium-potassium ATPase? | a. | It forms a transmembrane channel | d. | It is inhibited by cardiotonic by cardiotonic steroids | | b. | It can assume 2 different conformations, depending on whether or not it is phosphorylated. | e. | It makes electrogenic transport | | c. | It is inhibited by atractyloside |
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Matching |
Please match the following answers with the next 4 questions.
| a. | Enzymatic synthesis of eukaryote RNA | c. | Both | | b. | Enzymatic synthesis of eukaryote DNA | d. | neither |
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| ABCD | 47. | Inhibited by alpha-amanitin |
| ABCD | 48. | Pyrophosphate is released |
| ABCD | 49. | DNA template is required | | | ABCD | 50. | GTP is required. |
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