Final Exam Form 0 Spring 2002

Final Exam Form 0 - Bil 255 Spring 2002 Form 0 Final Exam Professors Glaser& Mallery Instructions Pick the BEST choice from among those given

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Unformatted text preview: Bil 255 5/2/2002 Spring 2002 Form 0 Final Exam Professors Glaser & Mallery Instructions: Pick the BEST choice from among those given. PART 1. New material since Test #2 - 40 questions : 30 by Professor Glaser & 10 by Mallery GLASER New Material (30 questions): 01. When glucagon is added to hepatocytes (liver cells) the level of cAMP in these cells is elevated and glucose is released by the cells. Caffeine is an inhibitor of cAMP phosphodiesterase. Do you expect (think carefully)? a) Caffeine to potentiate the action of glucagon, i.e., small amounts of glucagon become more effective b) Caffeine to inhibit the action of glucagon c) Cannot answer based on these facts 02. Cholera toxin is an enzyme that modifies some G proteins so that their GTPase activity is abolished. When you add cholera toxin to hepatocytes in tissue cultures in the presence of epinephrine (adrenaline) cAMP levels rise in these cells, and remain high even after adrenaline is removed. In this absence of cholera toxin, removal of adrenaline results in an immediate drop in cAMP. If you could examine in these cells the state of the α , β, γ subunits of G protein, would you expect? a) To find most of the G proteins as α , β, γ complex b) Most of the G protein as α subunit separate from β, γ complex 03. The binding of ACTH to its receptor in the adrenal cortex results in a large increase in intracellular cAMP. Each ACTH molecule generates many cAMP molecules because (think very carefully)? a) Each receptor can activate many G proteins b) Each G protein can activate many adenyl cyclase molecules c) Adenyl cyclase has high catalytic activity d) a and c apply e) b and c apply 04. Enzymes can act as on/off switches because? a) Their catalytic activity can be altered by phosphorylation/ dephosphorylation b) Their activity can be altered by allosteric regulation c) both a and b are correct 05. Upon addition of epidermal growth factor (EGF) to cells, the EGF receptor is phosphorylated at multiple sites on tyrosine residues. This phosphorylation? a) Is irrelevant to signal transduction by EGF b) Provides sites for activation of other proteins in the cell c) Each site is specific for a different pathway d) b and c apply 06. The best description of a cell cycle is ? a) A series of random events that culminate in cell division b) A series of sequential events that culminate in cell division c) A process with multiple check points d) a and b apply 07. Cyclins are ? a) Protein kinases c) Each cyclin only controls one protein kinase e) b and c apply b) Proteins that control protein kinases d) b and c apply 08. Programmed cell death (apoptosis) is mediated by ? a) Ion leakage from the cell c) A series of proteolytic events that destroy cell components b) Loss of ATP from mitochondria 255 Final 2002 - Form 0 - pg 2 09. In a classical experiment in embryology, the implantation of supernumerary limbs in chick embryos resulted in a) Neuronal death b) Survival of more neurons than in a normal embryo c) No effect on the number of neurons 10. Normal cells stop transit through the cell cycle when DNA is damaged. This process? a) Requires DNA ligase and p53 b) Requires p53 and expression of p21 c) Occurs in S phase d) a and b apply and results in inactivation of S phase cyclin-CdK e) b and c apply and results in inactivation of S phase cyclin-CdK 11. Which of the following events are likely to predispose a cell to become a cancer cell ? a) Loss of p53 gene b) Loss of DNA repair protein c) Decrease in cellular ATP levels d) a and c apply e) a and b apply 12. Which of the following statements is/are correct? a) Cells have a single check point before they enter the cell cycle. b) Cells have multiple check points that control progression through the cell cycle c) Cell size determines in part whether cells can enter the cell cycle d) a and c apply e) a, b, & c apply 13. Which of the following lists best describe mutations you might expect in a cancer cell? a) Constitutive production of a growth factor (example EGF), deletion of a DNA repair enzyme, absence of retinoblastoma gene, Ras proteins with no GTPase activity b) Absence of growth factor receptor, deletion of p53, nonfunctional DNA ligase, absence of ubiquitin c) Mutation in steroid hormone receptor that activates transcription absence of hormone, deletion of Ras gene, hyper-expression of p21, constitutive expression of CdK 14. The G protein consists of 3 subunits, α , β, γ. Which statement is correct? a) Only the α subunit is active in signal transduction b) The α and βγ subunits are active in signal transduction c) Signal transduction can be both stimulatory as well as inhibitory d) a and c apply e) b and c apply 15. Damage to DNA results in arrest of the cell cycle. This process requires (pick the best answer) ? a) Proteolytic degradation of MPF b) p53 to activate synthesis of p21 c) Inhibition of S phase cyclin/CdK complex d) a, b and c apply e) b and c apply 16. Retinoblastoma protein is a ? a) Positive regulator of cell growth c) Is itself controlled by phosphorylation b) Negative regulator of cell growth d) a and c apply e) b and c apply 17. MPF activity rises in a cell in an autocatalytic manner because MPF ? a) Activates itself by proteolysis b) Activates a phosphatase that activates MPF c) The phosphatase is activated by phosphorylation d) a and b apply e) b and c apply 18. You isolate a temperature sensitive mutant of hamster fibroblast which grows at 30° but not at 37°. You determine that one of the enzymes involved in ubiquitination of proteins is defective at 37°. You expect at 37° a) M-cyclin dependant protein kinase to be rapidly degraded. b) M-cyclin to be rapidly degraded. c) M-cyclin to be stable. d) M-cyclin dependant protein kinase to be stable. 19. A "stop transfer" sequence is required to ? a) Transfer proteins from cytoplasm to lumen of endoplasmic reticulum b) to insert nascent membrane proteins into lipid bilayers 255 Final 2002 - Form 0 - pg 3 20. The docking of vesicles at targets requires ? a) v-Snares b) t-Snares c) v-Snares and t-Snares that are complementary and bind to each other 21. The docking of a vesicle at the target membrane is ? a) Sufficient to cause membrane fusion b) Requires additional proteins that cause membrane fusion 22. Proteins that are destined to the cytoplasmic membrane are oriented in the Golgi so that the portion of the protein that will face the outside of the cell faces (think carefully) ? a) The lumen of the Golgi b) The cytoplasm around the Golgi 23. You expect the pH in trans Golgi to be relative to ER ? a) pH Golgi < pHER b) pH Golgi > pHER The following four questions are related. 24. You discover, what you believe is a new growth factor, a small protein molecular weight 10,000 which stimulates the growth of osteoblasts (cells that deposit bone). You wish to understand the mode of action of this OGF (osteoblast growth factor) and isolate, as a first step, its receptor. Fortunately, your next door neighbor has a collection of monoclonal antibodies directed at the surface of osteoblasts. You examine their ability to block the action of OGF and find that 4 out of 100 do so and 1 mimics the action of OGF. You also find that an FAB fragment of the latter no longer mimics the action of OGF but now blocks it s activity. Your initial observations suggest that this receptor is ? a) Adenyl cyclase b) A serine specific protein kinase c) A tyrosine specific protein kinase 25. You proceed in your research and you determine that after addition of OGF to cells, the amount of phosphatidyl inositol diphosphate decreases rapidly. You decide to measure the cytoplasmic pH and Ca++ concentration in osteoblasts after addition of OGF. You expect to find ? a) Cytoplasmic pH drops b) Cytoplasmic Ca++ drops c) Cytoplasm Ca++ raises d) a and b apply e) a and c apply 26. GTP γS is an analogue of GTP that can not be hydrolyzed to GDP + P1. You micro inject GTP γS into osteoblasts and find that it enhances the action of OGF you selected in the preceding question. Think carefully. Is the most likely explanation? a) OGF activates a G protein b) OGF inhibits Adenyl cyclase c) OGF activates RAS 27. You notice that after addition of additional “factors” and in the presence of OGF osteoblasts in tissue culture create bone-like structures. You accidentally select a mutant osteoblast which still requires OGF for growth, but does not deposit bone. You determine that the defect is in the OGF receptor and sequence the mutant gene as well as the normal and infer the following mRNA sequences (code words are correctly separated), unfortunately, it has 3 mutations but you immediately, as a good student in Biology 255, focus on the important which is ? Normal - - - AAU - CAG - CAU - UAU - GCU - AGA - Mutant AAU - CCG - CAU - UUU - GCU -AGG - (a) (b) (c) 28. Endocytosis of LDL requires ? a) LDL receptor b) Clathrins c) Both of these 29. The asparagine linked carbohydrate residue on mature proteins is ? a) Already present on the protein as it exits the ER b) The result of further modification of the carbohydrate chains as the protein transits through the Golgi 30. One of the earliest effects of the addition of the hormone to cells is a change in intracellular pH, the cells 255 Final 2002 - Form 0 - pg 4 transiently become more alkaline. You pre-treat cells with ouabain to block Na+/K+ ATPase and find that this alkalinization of cells is abolished. This observation is ? a) Consistent with alkalinization being the result of activation of Na+/H+ antiport b) These results argue against a role of Na+/H+ antiport in the alkalinization of these cells MALLERY New Material (10 Questions) 31. Water is a molecule that has a membrane permeability that is significantly greater than its partition coefficient indicates. a) true b) false 32. Which of the following types or methods of solute transport involve a carrier protein ? a) K+ ion channels b) NaK-ATPase c) facilitated diffusion d) Na+ ion channels e) choose this answer if all of the above are mediated by carrier protein 33. A ligand-gated channel protein’s conformation may be changed by which of the following ? a) a change in cell potential b) the binding of a solute, such as acetylcholine c) mechanical stress d) glucose cotransport e) none of these 34. The measured potentia l difference across a cell membrane-like barrier of some slime-ooze collected from the Mars Pathfinder on its return to Earth is -65 mV. The internal concentration of the cation Krypton [Kr+] is 10.0 millimolar and the exterior fluid concentration of Kr+ of 111 millimolar. We want to know how this ion distributes itself across this barrier. The ion distribution of krypton is most likely ? (use the Nernst potential) a) active b) passive c) exocytotic d) none of these is correct 35. A voltage gated channel in the pre-synaptic knob of many vertebrate neurons results in the opening of which of the following ion channels? a) Na+ b) K+ c) Ca+2 d) Cle) none of these 36. The hydrogen donor source for cyanobacterial photosynthesis is? a) H2S b) CH2O c) RuBP d) H2O e) none of these 37. Which of the following is most commonly found in a chloroplast? a) water soluble anthocyanin pigments b) protein crystals (aleuroplasts) c) 80s eukaryotic size ribosome d) highly repetitive & supercoiled DNA e) none of these 38. The absorption and action spectra of chlorophyll-b have absorption maxima in the visible spectrum in the ? a) U.V region b) green region c) yellow region d) red region e) none of these 39. The synthesis of ATP without the evolution of oxygen can only occur in photosynthesis by? a) non-cyclic electron flow b) phosphorescence c) cyclic electron flow d) fluorescence e) none of these is correct 40. Which of the following groups of plants contain both enzymes of carbon dioxide fixation (Rubisco & PEPcarboxylase)? a) purple -sulfur bacteria b) C3 plants c) C4 plants d) Calvin cycle plants e) none of these is correct Part II. Cumulative questions : 30 questions each for Professors Glaser and Mallery Mallery: 30 questions 255 Final 2002 - Form 0 - pg 5 41. Thermogenin and dinitrophenol are molecules that can integrate into mitochondrial membranes thereby short circuiting the existing H+ gradient across inner mitochondrial membranes. The most significant result of this event might be? a) mitoplasmic pH becomes more basic b) ATPase makes about same amount of ATP c) electron transport stops d) beta-oxidation stops e) choose this answer if none of these is correct 42. The philosophical approach of interpreting the properties of a living organism by a detailed examination of its constituent molecules and their individual properties that has been prevalent in 20th century is referred to as? a) vitalism b) natural selection c) reductionism d) micrographia e) choose this answer if none of these is the best choice 43. The derivation of the equations used to describe the theory of enzyme kinetics is attributable to ? a) Gregor Mendel b) Lenoir Michaelis & Maude Menten c) Frederick Meischer d) Matthias Schleiden & Theodor Schwann e) none of these is a best choice 44. Life and the living state is governed by a unique and different set of natural and physical laws than the rest of the universe ? a) true b) false 45. Which functional groups are present on this biomolecule ? HS-CH2-CH2-COOH a) ester & aldehyde b) amine & phosphate c) amine & carboxyl d) carboxyl & sulfhydryl e) choose this answer if none of the above is correct 46. Even though bound by the second law of thermodynamics, i.e., entropy, cells are able to become more complex and ordered, primarily because of coupled reactions ? a) true b) false 47. Which of the following is a weak electrostatic attraction/repulsion between atoms that is important in the macromolecular interactions of protein conformational shapes? a) covalent bond b) disulfide bond c) glycosidic bond d) van der Waal forces e) none of these is a best choice 48. The formation of a covalent bond with the accompanying elimination of a molecule of water between two monomer molecules is referred to as? a) condensation b) hydrolysis c) redox d) functional group transfer e) choose this answer if none of these is the best choice 49. A protein, which is capable of existing in different conformations due to the binding of regulator molecules is said to be a(n) ? a) a carrier protein b) a redox protein c) an allosteric protein d) a denatured protein e) none of these is a best choice 50. Entropy is a thermodynamic quantity that measures the degree of disorder of a system. If a cellular system exhibits an increase in its entropy, then we may say that the cell has shown a greater degree of order or complexity exhibited by that system. a) true b) false 51. Which of the following would have the least molecular weight, i.e., be the smallest in size (MW) ? a) oligopeptide b) dipeptide c) polypeptide d) protein e) none of these 52. The native conformation of most globular proteins is an interior pocket of hydrophilic amino acids held in place by their solubility with water and an exterior of hydrophobic amino acids held in place by their interactions with the fatty-like molecules. a) true b)false 53. The separation of proteins by gel filtration chromatography is also referred to as ? a) velocity sedimentation b) equilibrium density centrifugation c) size exclusion chromatography d) cell homogenization e) choose this answer if none of these is the best choice 54. A small aliquot (0.1 ml sample) of a 50 ml homogenate of rabbit liver tissue is shown to contain 1.5 mg of protein by the Bradford protein assay and to convert 6.0 micromoles of glucose to glucose-6-phosphate at 370C. 255 Final 2002 - Form 0 - pg 6 What is the specific activity of this enzyme? a) 2000 units/mg protein b) 1500 micromoles c) 0.2 units/mg protein d) 2.0 micromoles/mg protein e) choose this answer if none of these is the best choice 55. Which of the following curves of the rates of an enzyme catalyzed reaction would you expect to exhibit a single optimum rate of enzyme activity? A plot of the rate vs. _____? a) [S] substrate concentration b) pH c) [E] enzyme concentration d) [I] inhibitor concentration e) choose this answer if none of these is the best choice 56. Per individual glucose molecule, the greatest amount of substrate level phosphorylation takes place where? a) in the mitoplasm b) in glycolysis c) in Krebs cycle d) in matrix of mitochondria e) choose this answer if all of these is a best choice 57. Of the following lists of cellular components, which is required to make ATP by the process of chemiosmosis? a) ATP synthase b) a proton gradient c) ADP & Pi d) choose this answer if all of these are required 58. The pH is higher in the mitoplasm of a mitochondria than it is in the peri-mitochondrial space? a) true b) false 59. The Beer-Lambert law states ? a) that absorbance of a solution is proportional to the concentration of the solute in solution b) that cations will bind to an anionic resin c) that a peptide bond is stronger than a C=C bond d) that proteolytic cle avage of a protein yields only alpha-amino acids e) none of these is correct 60. Which of the following enzymes is a multienzyme complex, like PDH, but is directly within the Krebs Cycle? a) citrate synthetase b) isocitric dehydrogenase c) fumarase d) alpha-ketoglutarate dehydrogenase e) choose this answer if none of these is correct 61. The NADH produced in glycolysis may be utilized by the mitochondrial ETC via ? a) pyruvate dehydrogenase shuttle b) pheophytin c) PEP-carboxylase CO2 shuttle d) alpha-glycerol phosphate shuttle e) none of these is correct 62. Which of the following enzymes is NOT characteristic of the beta-oxidation pathway ? a) pyruvic dehydrogenase b) fatty acyl-coA dehydrogenase c) carnitine acyl-transferase d) fatty acyl-coA ligase e) choose this answer if all these are components of ß-oxidation 63. Which of the following is NOT a mitochondrial electron transfer chain component ? a) cytochrome oxidase b) cytochrome reductase c) ubiquinone d) iron-sulfur proteins e) choose this answer if all these are components 64. A negative standard redox potential means: a) electrons will flow from a redox couple component to a hydrogen standard b) electrons will flow from a hydrogen standard to a redox couple c) electrons will not flow at all 65. Which of the following is most likely a structural protein ?: a) ovalbumin b) hexokinase c) keratin d) hemoglobin e) none of these 66. The standard redox potential of a newly discovered redox couple (Mall-nucleotide = MALD + ? MALDH) is determined to be -0.11 volts and the standard redox potential of water (H2O <---> ½ O2 + 2H+ + 2e - ) is known to be +0.82V. Calculating the standard free-energy change [∆Go' = -nf ∆Eo’ ] will tell us how many ATP might 255 Final 2002 - Form 0 - pg 7 be made by passing electron between MALDH and O2. So how many ATP is it (Faraday = 23,000 calories)? a) 1 b) 2 c) 3 d) 4 e) none of these 67. In competitive inhibition of an enzyme catalyzed reaction, the inhibitor ? a) binds at a site different than the active site b) binds irreversibly at the active site c) binds only to the substrate d) lowers the Vmax of the enzyme at high [S] e) choose this answer if none of the above is correct 68. The Vmax for an enzyme catalyzed reaction ? a) always increases when the pH increases b) is one-half the rate observed when the concentration of substrate is at its lowest c) increases in the presence of a competitive inhibitor d) is limited only by the type of coenzyme involved e) choose this answer if none of the above is correct 69. Following homogenization of brain cells to disrupt the plasma cell membrane, the proteins of these cells might best be separated qualitatively from cell debris by which of the following techniques ? a) electrophoresis b) differential centrifugation c) X-ray crystallography d) gas chromatography e) choose this answer if none of the above is correct 70. The cell biology technique that coats the surface of a specimen with a metal, such as platinum, then has an electron beam excite the metal causing it to emit secondary electrons, which are focused on a cathode ray tube is a) isopynic density gradient centrifugation b) SDS-PAGE c) transmission electron microscopy d) scanning electron microscopy e) none of these is correct Glaser (cumulative material): 30 questions 71. The following proteins are required for DNA synthesis ? a) DNA polymerase, primase, sliding clamp b) Helicase, DNA ligase d) a and b apply e) b and c apply 72. RNA molecules have ? a) No secondary structure b) Fold at random c) RNA polymerase c) Can fold using base pairing rules into unique structures 73. In eucaryotes mRNAs at their 5' end are identified by ribosomes because ? a) They contain a TATA box b) Have a methylguanine cap c) Have a poly-A tail 74. The minimal components required for the proper function of a eucaryotic chromosome are ? a) Centromere b) Replication origin c) Telomere and telomerase d) All apply 75. Phosphorylation of proteins (enzymes) by ATP catalyzed by specific protein kinases is used to a) Modify the charge of protein b) Change the enzymatic activity of the protein (an on/off switch) 76. A number of proteins contain motifs (sequences) which repeat two or more times. These arose most likely during evolution by ? a) Exon shuffling b) Mistakes in DNA synthesis c) Homologous recombination d) a and b apply e) a and c apply 77. A strain of E. coli containing an integrated F-plasmid in the genomic DNA is also resistant to rifampicin, and able to grown in the absence of tryptophan. You observe that rifampicin resistance is transferred at high frequency while the ability of the recipient cells to grown in the absence of tryptophan is observed with low frequency. You conclude (pick best answer) ? 255 Final 2002 - Form 0 - pg 8 a) The two genes are on different chromosomes b) The location of rifampicin resistance gene is close to the site of integration of F-plasmid and the tryptophan gene is distal c) The location of rifampicin resistance gene is close to the beginning site for DNA transfer and the tryptophan gene is remote from this site 78. Retroviruses contribute to genetic diversity because (think carefully, pick the best answer) ? a) They contain RNA instead of DNA b) They contain reverse transcriptase c) Their genome is inserted as DNA into chromosomes d) During transcription and packaging of virus they sometimes (rarely) incorporate a host gene into viral particle as RNA 79. Homologous recombination cell occur between DNA molecules which at the site of recombination ? a) Have highly different nucleotide sequences b) Identical or nearly identical nucleotide sequences 80. The polymerase chain reaction requires the following components a) Deoxyribonucleoside triphosphates, DNA polymerase b) A primer oligonucleotide and DNA ligase c) Two different primer oligonucleotides d) a and b apply e) a and c apply 81. Tight junctions? a) Promote movement of proteins in membranes b) Restrict movement of proteins in membranes 82. The dideoxy nucleotide method for sequencing DNA is based on ? a) The chain termination of DNA polymerase action after a dideoxy nucleotide is incorporated into DNA b) The separation of DNA molecules that differ in length by one nucleotide c) The knowledge of DNA sequence to synthesize a primer d) a and b apply e) a, b and c apply 83. DNA fingerprinting detects differences between individuals by ? a) Determining nucleotide sequence of several genes b) Determining the sites of cleavage of DNA by restriction enzymes c) Determining the length of DNA fragments resulting from cleavage by specific restriction enzymes using sequence specific probes 84. Ouabain inhibits Na+/K+ ATPase. After treatment of cells with ouabain you expect ? a) K+ inside = K+ outside b) K+ inside > K+ outside c) K+ inside < K+ outside 85. Active transport is the movement of molecules across a membrane against its concentration gradient. Cells have evolved several mechanisms to accomplish this. Which of the alternatives below describe these mechanisms? a) A GTP driven glucose transport system and a light driven pump b) Light driven pumps, ATP driven pumps and coupled transporters c) ATP driven transport of sugars, and ion driven transport of amino acids d) All of these are correct 86. Ribosomes are ? a) Assembled in cytoplasm b) Assembled in nucleus c) The large and small subunits are assembled separately and only come together in the presence of mRNA d) a and c apply e) b and c apply 87. DNA Ligase requires ? a) An RNA primer b) ATP c) neither of these 88. Ribozymes are ? a) Enzymes that cleave ribonucleotide c) Enzymes that cleave RNA at specific sequences b) RNAs with catalytic activity d) a and b apply e) b and c apply 255 Final 2002 - Form 0 - pg 9 89. Steroid hormones, for example cortisone, control gene transcription by ? a) Intercalating in DNA and distorting the helix b) Binding to a specific steroid binding protein that acts as an RNA polymerase c) Binding to a specific steroid binding protein that binds to an enhancer sequence for steroid sensitive genes 90. You clone a DNA fragment in a plasmid using EcoR1 cleavage of the plasmid. This DNA is expressed in E. coli. It codes for an enzyme in amino acid metabolism. You have no amino acid sequence or DNA sequence for this gene but you wish to obtain the DNA sequence. You have a full DNA sequence of the original plasmid. The restriction map for plasmid with this gene inserted is: original plasmid inserted gene Hind III EcoR1 Not 1 EcoR1 In order to sequence this DNA you would release gene from plasmid with a) EcoR1 b) Hind III c) Not 1 d) Any will work e) b and c will work 91. The preferred arrangement of a lipid bilayer (lowest energy) in contact with water is? a) Sheet b) Helix c) A closed sphere 92. It is believed that mitochondria originated from ? a) Aerobic bacteria b) Anaerobic bacteria c) neither of these Consult the following restriction fragment length polymorphism detailed by hybridization to a DNA probe after digestion of human DNA with a restriction enzyme ? Parents A Parents B Infant Infant Father Mother Father Mother X Y __ ( ) __________________________________________________________________ __ __ __ __ __ __ __ __ __ __ __ __ __ (+) __________________________________________________________________ 93. Think carefully, based on this evidence alone a) Infant X is the child of Parents B c) One infant is the child of neither Parents A or B b) Infant Y is the child of Parents A d) a and c apply e) b and c apply 94. Flipase moves lipids from one side of the bilayer to the other. Its activity is best described as a) Equalize the lipid composition of both leaflets of the bilayer b) An enzyme that translocates lipid unidirectionally c) An enzyme that is lipid class specific d) a and c apply e) b and c apply 95. Receptor tyrosine kinase when activated by a signal molecule are phosphorylated on some of their own tyrosine residues. A mutant form of such a receptor has two of these tyrosine residues replaced by phenylalanine while a third is still present. You expect a) This mutation silent, i.e., the receptor is still fully functional b) The receptor is non-functional c) The receptor can activate some but not all of the metabolic pathways it normally activates 255 Final 2002 - Form 0 - pg 10 96. Which of the following statements is correct for eucaryotic cells? a) All cellular proteins are degraded at the same rate b) Each cellular protein is degraded at a different rate c) All proteins are degraded in lysosomes d) Some proteins are degraded in lysosomes, others in proteosomes e) b and d are correct 97. Which of the following statements is correct? a) All proteins have alanine at their amino end b) All proteins initially have methionine at their amino end but this may be removed from the mature protein c) The code for the first amino acid at the amino end of protein can be any coding triplet 98. The fluidity of a membrane is reduced by a) Cholesterol and presence of unsaturated fatty acids b) Cholesterol and the presence of saturated fatty acid c) Transmembrane proteins 99. Which of the following would you consider probably useful approaches for cancer therapy? a) Inhibitor of telomerase b) Activator of Ras c) Inhibitor of tyrosine specific protein kinase d) a + b apply e) a + c apply 100. You measure the carcinogenicity (i.e. number of animals with tumors) of a new medication to cure malaria. Which of the following results (a or b) is more likely if the drug is carcinogenic? 10 % of Animals with tumors, after 2 years of treatment 10 % % 0 0 (a) Dosage of drug (b) Dosage of drug Congrats to our graduates & to the rest of you, see you when you get back in the fall. Have a Great Summer. 255 Final 2002 - Form 0 - pg 11 ...
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This document was uploaded on 10/27/2011 for the course BIL 255 at University of Miami.

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