exam-18-december-2009-questions

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Studocu is not sponsored or endorsed by any college or university Exam 18 December 2009, questions Molecular Biology (McGill University) Studocu is not sponsored or endorsed by any college or university Exam 18 December 2009, questions Molecular Biology (McGill University) Downloaded by Katie Yeung (katieyeung0803@gmail.com) lOMoARcPSD|31670854
Student Name: Student Number: (PIease Print) FACULTY OF SCIENCE FINAL EXAMINATION 2005 BIOL 200 - MOLECULAR BIOLOGY (002) Examiners: Profs. F. Fagotto and P. Lasko Date: December 16,2005 Time: 2:OO p.m. Place: Gym INSTRUCTIONS: 1. 2. 3. 4. 5. 6. 7. 8. 9. All students will write the exam in the room assigned and posted beforehand. All questions must be answered in the examination booklets provided. Your name and student number must be entered on your examination sheet as well as any examination bookIets that you have used. Both the examination sheet and booklets must be submitted at the end of the exam. Calculators are not needed for any question on this exam but are permitted in the exam room. A simple translation dictionary may be used during the exam by persons in their first year of studies in English. If you find any questions ambiguous, specify the question number and explain your concerns at the bottom of h s cover sheet. (Important): It is essential that your answers are concise. Each question is followed by our suggestion fox the maximum number of words your answer should require. The questions can all be answered fully and correctly in fewer words than our suggestions indicate. It is unnecessary to answer the questions in complete sentences. Responses that exceed the suggested length limit may not be read in full, and may be marked lower if incorrect information is included. This exam consists of 4 pages (1 5 questions) including the cover page. Am bigiiities: Downloaded by Katie Yeung (katieyeung0803@gmail.com) lOMoARcPSD|31670854
BIOL 200 - FINAL EXAMINATION MOLECULAR BIOLOGY (002) Page 2 Question I. (6 points) Identify the site at which each of the following molecules interacts with pre-&A. (5 words each). a.U1 snRNA b. U2 snRNA c. U2AF (U2-associated factor) Question 2. (4 points) What virally - encoded protein is required for transport of unspliced HIV genomic RNA from the nucleus to the cytoplasm? (5 words). Question 3. (4 points) You have identified a new protein and have found that it contains two RRM domains. What is its function most likely to be? (5 words). Question 4. (8 points) You obtain the sequence of a gene containing 10 exons, 9 introns, and a 3’ UTR containing a polyadenylation consensus sequence. The fifth intron also contains a polyadenylation consensus sequence. To test whether both potential polyadenylation sites are used, you isolate mRNA and find a longer transcript from muscle tissue and a shorter mRNA transcript from all other tissues. a. What is the most Iikely mechanism that accounts for these two transcripts b. What must be present in muscle cells for them to express the longer transcript? being produced from the same gene? (5 words) (4 points) (20 words) (4 points) Question 5. (8 points) A new microorganism has been discovered on Mars. Its genome is composed of double - stranded DNA, but it contains only two bases, cytosine and guanine. Nevertheless, proteins from this organism are composed of the same 20 amino acids as are found on Earth. a. Assuming that protein synthesis in this organism utilizes mRNA and tRNA intermediates and operates similarly to that on Earth, what is the theoretical minimum size for a codon in the Martian organism? Why? (10 words) (3 points) b. Would genes from this Martian organism be transcribed efficiently in cell extracts prepared from E. coli? Why or why not? (20 words) (3 points) c. If two tubes, one containing Martian DNA and one containing E. coli DNA, were incubated at 95 C, which would contain a larger proportion of double - stranded versus single - stranded DNA? Why? (I 0 words) (2 points) Question 6. (8 points) DNA Replication a. Describe briefly the activity of the primase and why it is required for replication. (20 words) (4 points) b. What is the role of topoisomerase at the replication fork? (20 words) (I point) c. Describe in a few words the biochemical process performed by this topoisomerase. (20 words) (2 points) d. In which region of the fork is the topoisomerase active? (5 words) (1 point) Downloaded by Katie Yeung (katieyeung0803@gmail.com) lOMoARcPSD|31670854
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BIOL 200 - FINAL EXAMINATTON 2005 MOLECULAR BIOLOGY (002) Page 3 Question 7. (7 points) Nucleosome: Describe the main features of the nucleosome: a. What are the two major components? (5 words) (2 points) b. What is its structure (organization of the components)? (20 words) (3 points) c. What is its function? (20 words) (2 points) Question 8. (4 points) Hetero/euchrom atine: a. What is (in general) the state of activity of a gene in heterochromatic regions? b. Which chromatin component is modified in euchromatin, (1 point) (5 words) c. what is the most frequent type of modification, (5 words) (1 point) d. and which is the residue modified? (5 words) [ 1 point) (5 words) (1 point) Question 9. (8 points) Telomeredtelomerase : a. b. c. d. e. f. What is the modification brought to chromosomal DNA by the telomerase? (5 words) (2 points) What is the function of this modification? (20 words) (2 points) What happens to chromosomes in the absence of telomerase activity? (20 words) (1 point) In addition to proteins, what type of molecule is present in the telomerase? (5 words) (1 point) What is the role of this non - protein molecule in the activity of the telomerase? (20 words) (1 point) What is the state of chromatin condensation in the telomere region? (1 word) (1 point) Question 10. (4 points) Genes: In higher eukaryotes, does the len& of a gene and the length of the corresponding cDNA match? Explain briefly. (50 words) Question 11. (8 points) Transgenes and gene disruption: Imagine that a transgene X has been randomly inserted in a mouse chromosome, in the reglon containing an essential gene A. a. Propose three locations of the insertion that could cause disruption of gene A, and explain briefly how the insertion would disrupt the gene. (50 words) b. Propose one location of the insertion that may have no effect on gene A activity. (20 words) (1.5 points) c. If gene A is essential for cell function, what phenotype do you expect for the homozygous progeny of two mice carrying a transgene disrupting gene A? (5 words) (2 points) (4.5 points) Downloaded by Katie Yeung (katieyeung0803@gmail.com) lOMoARcPSD|31670854
BIOL 200 - FINAL EXAMINATION 2005 MOLECULAR BIOLOGY (002) Page 4 Question 12. (7 points) DNA sequencing: a. Explain in a few words the principle of DNA sequencing. (50 words) (4 points) b. Which are the reagents that must be present in a sequencing reaction? (20 words) (3 points) Question 13. (7 points) Cloning: You want to move a cDNA fragment X from vector A to vector B: a. What type of enzyme would you use to take X out of vector A? (5 words) (2 points) b. What is special about the sites recognized by such enzymes? (5 words) (2 points) c. What enzyme would you use to paste the fragment in vector B? (5 words) d. Is it necessary to cut both the fragment and vector B with exactly the same enzymes? Explain. (50 words) (2 points) (I point) Question 14. (9 points) Sequence analysis: Use the list of amino acids (3 letter abbreviation) with the main properties of their residues to analyzelcompare the follow - ing sequences from protein X. Note that protein X is a soluble cytoplasmic protein. A) Ser Glu Gln Ala Cys Asp Lys Lys Arg Gln Gly B) Thr Ala Gly Glu Leu Ile Gly Asn Ile Asp Tyr Met Leu C) Ala Tyr Ala Leu Leu Met Phe ne Val Ala Gly Ala B’) Thr Ala Gly Glu Asp Glu Gly Asn Ile Asp Tyr Met Leu B”) Thr Ala Gly Glu Leu Ile Gly Asn Leu Glu Tyr Met Leu Amino acid list : Hydrophilic basic: Lys, A r g , His Hydrophilic acidic : Glu, Asp Hydrophilic uncharged: hydroxyl residue: Thr, Ser, amide residue: Asn, Gln Hydrophobic: Ala, Val, Leu, Ile, Met, Phe, Trp, Tyr Others : Gly, Cys, Pro a. take sequences A), B) and C): by loolung and the amino acid composition of these fragments, infer the general properties of each of these fragments and predict the most likely location within protein X. (3 points) (50 words) b. Is there a least one of these sequences that would aIlow you to predict the secondary conformation? Explain. (50 words) (2 points) c. B”) and B’”) are two mutant alleles of B). For each of these alleles, do you expect a strong or weak effect on protein stmcturelfunction? Explain briefly why? (50 words) (2 points) Question 15. (8 points) Protein separatiodpurification: a. Name two different techniques to separate proteins according to their mass. b. In each case, explain how proteins of different sizes are separated. (50 words) (20 words) (2 points) (6 points) Downloaded by Katie Yeung (katieyeung0803@gmail.com) lOMoARcPSD|31670854