Test 2 Spring 2002

Test 2 Spring 2002 - Bil 255 - Cellular & Molecular...

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Unformatted text preview: Bil 255 - Cellular & Molecular Biology Dr. Luis Glaser Spring 2002 Test #2 – 4/04/02 FORM 0 Directions: Choose the BEST answer from among those given. Honor Code: On my honor, I have neither given nor received aid on this exam.__________________________ signature 1. When DNA synthesis is initiated at origin of replication, the two parental strands are replicated (think carefully)? a) In opposite directions b) In same direction c) One continuously and one discontinuously d) a and c apply e) b and c apply 2. DNA synthesis is always initiated by? a) An RNA primer b) A guanosine cap c) A deoxyribonucleotide triphosphate d) none of these 3. Some mutations (base changes in DNA) are phenotypically silent (i.e., have no biological effect). Their most likely location is in? a) Exons b) Introns c) none of these 4. Uracil is a base unique to RNA; it pairs with? a) Guanosine b) Cytosine c) Adenine d) none of these 5. Eucaryotic messenger RNA has? a) A poly-A tail at 5' end and a methyl G cap at 3' end b) A poly-A tail at 3' end and a methyl G cap at 5' end c) neither of these is correct 6. The function of tRNAs is to translate mRNA sequence. a) There is only one tRNA for each amino acid b) There are multiple tRNAs for some amino acids c) There are multiple tRNAs for all amino acids d) none of these is correct 7. The ribosome contains? a) One binding site for tRNA d) none of these is correct b) Three bind ing sites for tRNAs c) Two binding sites for tRNAs 8. A given messenger at any time will have attached to it ? a) One ribosome at the end b) One ribosome at each end c) Multiple ribosomes in the process of synthesizing protein d) none of these is correct 9. The minimal components required for function of a eucaryotic chromosome are a) Centromere b) Replication origin c) Telomere and telomerase d) All these apply 10. In general the DNA in each cell of the body of a eucaryotic organism, for example man, a) Is different in each cell type b) Is the same in each cell type 11. Proteins that control gene expression, i.e., control the frequency of transcription, bind to? a) Single bases in DNA b) Multiple bases in DNA c) Bind to DNA in either the major or minor groove d) a and c apply e) b and c apply Bil 255s02 – Test 2 Form 0 – page 2 12. In procaryotes the synthesis of enzymes required to make essential amino acids/vit amins/sugars depends on the availability of these in the fluid in which cells grow. Repressors are best described as ? a) Proteins that control nutrient uptake by cells b) Proteins that bind to DNA at promoter regions, dependent on concentration of specific ligands in cells, for example, an amino acid c) Are a component of RNA polymerase d) none of these is correct 13. Each eucaryotic gene is controlled by ? a) Single regulatory protein b) Multiple regulatory proteins c) Both may apply 14. You chemically link the amino acid alanine (Ala) labeled with 1 4 C to the tRNA for leucine. You use this molecule in an in vitro system to synthesize a protein using the appropriate mRNA, ribosomes, etc. The initial coding sequence for this protein is … AUG-UUU-GCU-CUU-GCG You expect to find radioactive alanine (think carefully)? a) In position 1 and 3 b) In position 3 c) In position 4 d) In position 5 e) none of these 15. Think about the following statement, "The genetic information present in gametes (eggs or sperm) is absolutely identical to the genetic information present in somatic cells of the individual that generated these cells." Is this statement ? a) True b) False 16. The life cyc le of a retrovirus ? a) Requires functional DNA repair enzymes b) Requires functional reverse transcriptase c) host cell RNA polymerase d) a and b apply e) b and c apply Note Questions 17, 18, & 19 are related 17. You clone the portion of mouse DNA that codes for the enzyme hexokinase (involved in glycolysis), as well as a small portion of adjacent DNA. You sequence a portion of this DNA and you use it to identify clones for the same DNA region (coding for hexokinase) from pig/human/horses/baboons using hybridization and a radioactive oligonucleotide with the mouse sequence as a probe. In order to accomplish this you hybridize the protein to your clones at ? a) High stringency b) Low stringency c) It does not matter, either will work 18. Having obtained clones for the gene for hexokinase from mouse/pig/horse/baboon/human, you examine their pattern of cleavage by restriction enzymes. You expect ? a) The pattern to be totally different b) The pattern of cleavage of baboon & human genes to be more similar than mouse & human c) The pattern of cleavage of baboon & human genes to be as different from each other as mouse & human 19. You completely sequence the hexokinase genes from all species and you compare the sequence, not only at the nucleotide level, but also of the protein (i.e., hexokinase) for which they code. You expect ? a) More divergence in introns than in exons b) Less divergence in introns than in exons c) The amino acid sequence of protein to be more related than nucleotide sequence d) a and c apply e) b and c apply 20. When phosphatidyl ethanolamine is present in a lipid bilayer you expect the ethanolamine to be ? a) At the center of the bilayer b) In the aqueous phase c) neither of these is correct Bil 255s02 – Test 2 Form 0 – page 3 21. 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 23. A cDNA library differs from a genomic DNA library because ? a) It is less complex b) The coding sequence is intact c) It requires reverse transcriptase in its preparation d) All the above apply 22. The region of a membrane protein that traverses the lipid bilayer is usually arranged on ? a) An extended chain of amino acids b) An α helix c) A pleated sheet d) none of these 24. Where two cells are fused, after a short period of time you expect ? a) All membrane proteins are now randomly mixed b) Some membrane proteins are constrained from free diffusion c) neither of these 25. Some proteins form pores that allow entry or exit of hydrophilic (water soluble) molecules from cellular compartments. You expect such proteins to traverse membranes ? a) Once b) Twice c) Multiple times d) none of these 26. For all cells is ? a) Na+ inside > Na+ outside or is b) Na+ outside > Na+ inside 27. The concentration of amino acids in liver cells is generally higher than in extracellular fluid. In the presence of ouabain, which inhibits Na+/K + ATPase, you expect to find for the amino acid alanine (Ala) a) Ala inside < Ala outside b) Ala inside > Ala outside c) neither of these is correct 28. Gatorade is a bad tasting mixture of glucose and NaCl, but is very effective in restoring glucose to the body. You attempt to improve the taste of Gatorade by replacing the NaCl with either NH4 Cl or KCl, and neither works. you consult a student, well trained in BIO 255, who explains to you that ? a) NaCl is required to match the Na+ concentration in blood b) NaCl facilitates the exit of glucose into blood stream from intestinal epithelial cells c) NaCl is required for glucose transport into intestinal epithelial cells d) none of these is correct 29. In a cell under normal physiological conditions, activation of the Na+/H+ antiport will ? a) Increase cellular pH (i.e., cell becomes alkaline) b) Decrease cellular pH (i.e., cell becomes more acid) c) The question cannot be answered 30. Which of the following statements is correct regarding ATP driven pumps? a) The only ATP driven pump is the Na+/K + ATPase b) Eucaryotic cells contain a variety of ATP driven pumps including Na+/K + ATPase, Ca++ ATPase and H+ ATPase c) All ATP driven pumps are in the cytoplasmic membrane d) b and c are correct Bil 255s02 – Test 2 Form 0 – page 4 31. Na+/H+ antiport is one of the primary regulators of intracellular pH. When the fluid surrounding a cell contains no Na+ would you expect the cells cytoplasm ? a) To become more acid b) To become more alkaline 32. Some proteins have covalently attached to them fatty acids or more complex lipid molecules. You expect these lipid molecules to be ? a) Located in the interior of the protein b) Located on the surface of the protein c) Inserted into lipid bilayers d) a and c apply e) b and c apply 33. The cytoplasmic membrane of eucaryotic cells contains glycoproteins and glycolipids. You expect the carbohydrate portion of these molecules to be primarily ? a) Facing the inside of the cell b) Facing the outside of the cell c) Both 34. When the ribose reaches a code word UGA, it ? a) Releases the nascent protein still linked to tRNA b) Releases the nascent protein without tRNA c) Binds a release factor which allows peptidyl-transferase to release the protein d) a and c apply e) b and c apply 35. A particular cell type can potentially utilize 3 different regulatory proteins that control gene expression to generate different phenotypes by utilizing any possible combination of these proteins from 0 to 3. How many potential phenotypes can arise? a) 3 b) 6 c) 8 d) none of the above 36. For the expression of a eucaryotic protein in a procaryotic (bacterial) cell, using a plasmid, the plasmid needs minimally to have DNA sequences that code for ? a) An origin of DNA replication, a procaryotic ribosome binding site, a procaryotic promoter b) A complete copy of the eucaryotic gene coding for the protein c) A complete copy of the cDNA for the protein d) a and b apply e) a and c apply 37. To create a transgenic cow that would synthesize a human protein in milk, you would ? a) Inject total human DNA into the mammary gland b) Select embryonal stem cells (ES) transfected with human gene under control of a promoter expressed in all somatic cells c) Select ES cells transfected with a human gene under control of a DNA sequence specific for proteins secreted in milk such as lactalbumin and transfer these cells to early blastulas d) None of the above 38. 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 39. When RNA polymerase II reaches a signal for poly-adenylation, it and the RNA transcript are released. You compare the state of phosphorylation of the RNA polymerase in the process of transcription and the released protein, and you expect to find, as the most likely result ? a) The released protein is not phosphorylated b) The released protein is highly phosphorylated Bil 255s02 – Test 2 Form 0 – page 5 40. A cDNA library is prepared from muscle cells and liver cells. You expect the genes found in these two libraries to be ? a) The same b) Partially overlapping c) Totally different d) none of these Questions 41 and 42 are related: 41. Two children are born in a hospital at the University of Florida. Since Gators are not careful, the blood samples taken from the two mothers may have been mislabeled and there is a possibility that the parents took home the wrong child. Before alarming anybody, a bright UM graduate suggests a RFLP analysis to see whether she can solve the problem. The results with a probe are: Parents A Mother Father ______ Child X They took home ________ Parents B Mother Father ______ Child Y They took them ________ ______ ________ ______ ______ ______ ________ a) Child X does belong to Parents A c) One child could belong to either parent ________ b) Child Y does not belong to Parents B d) a, b, and c are correct e) only a and c are correct 42. The experiment in question 41 was repeated using a different probe for a different region of the genome. (Think carefully) a) The new probe can confirm or negate the positive identification of the parents of either child. b) If the probe used in question 41 leads to the conclusion that a child cannot belong to a particular set of parents, can the new probe reverse the conclusion. c) A and B apply d) The question cannot be answered. 43. DNA synthesis requires ? a) One DNA polymerase b) Multiple DNA polymerase c) A different DNA polymerase synthesizes DNA complementary to leading and logging strand. d) One DNA polymerase called Polymerase III in E.coli synthesizes the leading and lagging strand and Polymerase I replaces the RNA primer by Nick translation. 44. The deamination of cytosine to uracil before DNA replication, if not repaired will result in ? a) Two daughter cells with a mutation. b) One daughter cell with a mutation. c) Both cells will be normal 45. Protein in cells can be hydrolyzed to yield small peptides or amino acids by ? a) Caspases b) Conjugation with ubiquitin and degradation by proteosome c) Proteases in lysosomes d) A, B, and C, apply 46. The concentration of mRNA’s in cytoplasm of Eucaryotic cells is controlled by ? a) Transfer of mRNA to the nucleus b) Degradation by nucleases c) Control of gene transcription d) A & B apply e) B & C apply Bil 255s02 – Test 2 Form 0 – page 6 47. The sequence of the human genome has identified 30,000 genes that, if expressed, can be translated into protein. You expect ? a) Proteins coded by all 30,000 genes to be present in hepatocytes (liver cells) b) A significantly smaller number of different proteins expressed in hepatocytes c) The same proteins are expressed in heart as in skeletal muscle. d) none of these 48. The sequence of the human genome has identified 30,000 ± 3,000 sequences that can be expressed as proteins. Research determination of the number of different proteins expressed in the aggregate of the major cell types in humans may be as high as 60,000. You conclude from this: a) The sequence of human genome is incorrect b) Exon shuffling occurred in the DNA c) Differential splicing is very prevalent 49. The synthesis of proteins always start with code AUG (methionine) You expect cells to have (pick the best answer). a) A single transfer RNA that recognizes this code word b) Two transfer RNA’s that recognize this code word c) One transfer RNA that recognizes the codon as an initiator and another that recognizes internal methionine sites. 50. The syntheses of DNA in eucaryotic cells requires an active telomerase. This requirement is necessary (think carefully) a) For each cycle of DNA replication b) To maintain complete copies of the genome after multiple cycles of DNA replication. Bil 255s02 – Test 2 Form 0 – page 7 ...
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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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