B250WT1S05 - M.CO 411 MED PR E D41 1.C OM BIL 250/P Exam 1...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: M .CO 411 MED - PR E D41 1.C OM BIL 250/P Exam 1, the underlined choice is the correct answer. OM - PR EME I. Multiple choice questions (Choose the best answer from among those available) - PR EME D41 1.C 1. A virus contains 10% adenine, 24% thymine, 30% guanine, and 36% cytosine. Is the genetic material in this virus ______________? double-stranded DNA single-stranded DNA single-stranded RNA double-stranded RNA a circular DNA P 1.C OM - PR EME D41 1.C OM A. B. C. D. E. - PR EME D41 2. Frame-shift mutations are often caused by which of the following changes to nucleotides in DNA? chemical modification insertion reversion transversion suppression D41 1.C OM - PR EME D41 1.C OM A. B. C. D. E. OM - PR EME D41 1.C Ethidium bromide Ethylmethane sulfonate Ionizing radiation 5-bromouracil Hydroxyurea D41 1.C A. B. C. D. E. OM - PR EME 3. Which of the following mutagens would be most likely to physically damage DNA? A. B. C. D. E. Much faster DNA polymerase than prokaryotes Multiple origins of replication Theta replication Rolling circle replication Antiparallel nature of DNA strands - PR EME D4 11. COM - PR EME D4 11. COM - PR EME 4. The huge human genome can be replicated in just 8 hours or so; how is this possible? PRE MED 411 .CO MPRE M ED4 11. COM 5. Which of the following can function as a RNA polymerase? A. Topoisomerase I B. Helicase C. Ligase M .CO 411 MED - PR E - PR EME D41 1.C OM D. Primase E. Gyrase - PR EME D41 1.C OM 6. In E. Coli, the high specificity that RNA polymerase shows for regions just upstream of coding sequences is conferred by: The alpha subunits The beta subunits The sigma factor The licensing factors Single-stranded binding protein - PR EME D41 1.C OM A. B. C. D. E. D41 1.C OM 7. In what way does Transcription differ from replication? The template is copied from its 3’ end to its 5’ end. Complementary base-pairing is maintained. New bases are added to the 3’ OH group. Uracil nucleotides are incorporated. It starts at one or more specific locations. - PR EME D41 1.C OM - PR EME A. B. C. D. E. D41 1.C OM 8. Which of the following is NOT an appropriate descriptor of the genetic code? Degenerate Non-overlapping Commaless Ambiguous Nearly universal - PR EME D41 1.C OM - PR EME A. B. C. D. E. D41 1.C OM 9. In which type of E. coli RNA would you most likely find chemically modified bases? - PR EME D4 11. COM - PR EME A. B. C. D. E. rRNA tRNA snRNA scRNA mRNA PRE MED 411 .CO MPRE M ED4 11. COM - PR EME D4 11. COM 10. Who first showed that nonvirulent strains of Streptococcus pneumonia can be transformed to virulent strains by mixing them with a culture of a virulent strain that had been heat-killed? A. B. C. D. Chargaff Crick Griffith Avery/MacCleod/McCarty M .CO 411 MED - PR E - PR EME D41 1.C OM E. Hershey/Chase OM 11. The difference between a nucleotide and a base is the presence of: One versus two heterocyclic rings Ribose versus deoxyribose Sugar and phosphate Nitrogenous base None of the above. D41 1.C OM - PR EME D41 1.C A. B. C. D. E. Nucleosomes Chromosomes Supercoiling Histones Double helix - PR EME D41 1.C OM - PR EME D41 A. B. C. D. E. 1.C OM - PR EME 12. Which of the following modes of DNA packaging would be found in an investigation of the bacterial nucleoid? - PR EME D41 1.C OM 13. When codons that code for the same amino acid differ in their ________, a single tRNA might bind both of them through wobble base pairing. - PR EME D41 1.C OM A. 5' base B. middle base C. 3' base D41 1.C OM Use the following diagram for the next two questions. Solid circles represent amino acids. - PR EME 3’ COM 5’ B C 2 3 1 MPRE M .CO 411 MED PRE 4 14. The next step in the translation of this mRNA will be the formation of a peptide bond between which two amino acids? ED4 11. COM - PR EME D4 11. COM - PR EME D4 11. A A. amino acid 2 and amino acid 3 M .CO 411 MED - PR E - PR EME D41 1.C OM B. amino acid 2 and amino acid 4 C. amino acid 1 and amino acid 3 D. amino acid 1 and amino acid 2 1.C OM 15. After the peptide bond forms, what will happen? D41 1.C OM - PR EME D41 1.C OM - PR EME D41 1.C OM - PR EME D41 1.C OM - PR EME D41 1.C OM - PR EME D41 A. tRNA A will be carrying the polypeptide and it will shift to the P site. B. tRNA A will be carrying the polypeptide and it will shift to the A site. C. tRNA B will be carrying the polypeptide and it will shift to the P site. D. tRNA B will be carrying the polypeptide and it will shift to the A site. OM - PR EME The above diagram of a generalized tetranucleotide will serve as a basis for the following question. - PR EME D4 11. 5’-TGTC-3’ 5’-ACAG-3’ 3’-TGTC-5’ 3’-ACAG-5’ COM A. B. C. D. COM - PR EME D41 1.C 16. Given that the DNA strand which served as a template for the synthesis of this tetranucleotide was composed of the bases 5'- A C A G - 3', fill in the parentheses (in the diagram) with the expected bases. PRE MED 411 .CO MPRE M ED4 11. COM - PR EME D4 11. 17. When considering the initiation of transcription one often finds consensus sequences located in the region of the DNA where RNA polymerase(s) bind. Which are these common consensus sequences? A. B. C. CAAT, TATA GGTTC, TTAT TTTTAAAA, GGGGCCCC M .CO 411 MED - PR E 1.C OM any trinucleotide repeat satellite DNAs - PR EME D41 D. E. 1.C OM - PR EME D41 125/216 5/6 1/216 1/6 D41 A. B. C. D. 1.C OM - PR EME D41 1.C OM 18. “Breaking the Genetic Code” has been referred to as one of the most significant scientific achievements in modern times. Use of polynulceotide phosphorylase to produce synthetic “mRNAs” by Nirenberg, Matthaei, and Ochoa in a cell-free protein-synthesizing system was one of these ground breaking experiments. Suppose they used mixed copolymers, A and C in a ratio of 1A:5C. What is the probability for a AAA sequence occurring? 1.C OM - PR EME 19. What activity of DNA polymerase I reported by Arthur Kornberg in 1957 is responsible of the removal of the RNA primer in E. Coli? 3’ to 5’ exonuclease primase 5’ to 3’ polymerase 3’ to 5’ polymerase 5’ to 3’ exonuclease - PR EME D41 1.C OM - PR EME D41 A. B. C. D. E. - PR EME D41 1.C OM 20. Given below is a hypothetical "wild type" polypeptide containing twelve amino acids (each letter arbitrarily represents one amino acid). Assume that gene X is responsible for its synthesis. OM A-B-C-D-E-F-G-H-I-J-K-L PRE MED 411 .CO MPRE M ED4 11. COM O-S-E-Y-I-U-T-S-R-J-K-L A-B-C-D-E-F-G-H-I-J-K-L -L -K-L A-B- - PR EME D4 11. COM A. B. C. D. E. - PR EME D4 11. COM - PR EME D41 1.C The amino acid "A" is at the C terminus and amino acid "L" is at the N terminus. Select the sequence of amino acids from gene X under the following circumstances : A nonsense mutation involving bases 7, 8, and 9 in the coding region of the mRNA (counting from the 5' end of the coding region of the mRNA), from the following five choices: M .CO 411 MED - PR E OM - PR EME D41 1.C OM - PR EME D41 1.C OM - PR EME D41 1.C 21. Sidney Brenner argued that the genetic code was non-overlapping because he thought that coding restrictions would occur if it were overlapping. A major argument against an overlapping code involved the effect of a single nucleotide change. In an overlapping code ______ amino acid(s) would be affected by a point mutation while in a non-overlapping code ______ amino acid(s) would be affected. A. one, one B. two, one C. one, two D. two, two E. many, many - PR EME D41 1.C OM 22. Purines and pyrimidines found in DNA could exit in tautomeric forms, each differing by only a single proton shift in the molecule. Such tautomeric shifts could result in mutation through the formation of anomalous pairs, such as: D41 1.C OM - PR EME D41 1.C OM A. A= G and T = C pairs B. A = T and G = C pairs C. A = A and T = T pairs D. A = C and G = T pairs E. G = G and C = C - PR EME D41 1.C OM - PR EME 23. Are histone proteins the only proteins associated with chromosomes? (The credit from this question is awarded to every student) A. Yes B. No C. It depends on the life cycle. COM - PR EME D4 11. COM - PR EME D41 1.C OM 24. Ribosomes are known to participate in protein synthesis, which one of the following statements concerning ribosomes and ribosomal RNA is NOT correct? A. rDNA is that portion of a genome which is involved in the production of ribosomal RNA. B. Each ribosome is specific for the protein synthesized in association with it. C. Ribosomal RNA molecules provide the basis for all important catalytic functions associated with translation. D. The rRNA genes are part of the moderately repetitive DNA fraction. PRE MED 411 .CO MPRE M ED4 11. COM - PR EME D4 11. 25. The process of tRNA "charging" does NOT involve __________. A. rRNA B. tRNA C. aminoacyl synthetase D. ATP E. an amino acid M .CO 411 MED - PR E OM - PR EME D41 1.C Short answer questions: - PR EME D41 1.C OM 1. Why did Hershey and Chase choose 32P and 35S for use in their experiment? What did their experiment demonstrate? Could they have used radioactive isotopes of carbon (C) and oxygen (O) instead? Why or why not? (2 points) - PR EME D41 1.C OM - PR EME D41 1.C OM Key points needed in the answer: Proteins contain sulfur in the amino acids cysteine and methionine. However, proteins do not typically contain phosphorous (or have very limited amounts due to the phosphorylation of certain proteins by protein kinases). DNA contains a lot of phosphorous due to its sugar-phosphate backbone but no sulfur. Hershey and chase chose the isotopes 32P and 35S because these radioactive elements would allow them to distinguish between proteins and DNA molecules. Only DNA would contain the isotope 32P, and only proteins would contain the isotope 35S. - PR EME D41 1.C OM Their experiment demonstrated that DNA is the genetic material of the bacteriophage (important information needed to be mentioned in student’s answer). - PR EME D41 1.C OM - PR EME D41 1.C OM They could not have used radioactive isotopes of oxygen and carbon, because DNA and proteins both contain significant amounts of carbon and oxygen. The molecules were labeled with the radioactive isotopes in vivo by using phage to infect E. coli cells grown in media containing the radioactive isotope. Both DNA and proteins in the phage progeny would have received the radioactive isotopes. Hershey and Chase would have been unable to isolate only DNA molecules or proteins that contain radioactive isotopes of these elements. 1.C OM 2. Why is primase required for DNA replication? (1.5 points) - PR EME D4 11. COM - PR EME D41 Key points needed in the answer: Primase is a DNA-dependent RNA polymerase. Primase synthesizes the short RNA molecules, or primers, that provide a 3’-OH to which DNA polymerase can attach deoxyribonucleotides in replication initiation. The DNA polymerases require a 3’-OH to which they add nucleotides, and therefore they cannot initiate replication without a primase. Primase does not have this requirement. PRE MED 411 .CO MPRE M ED4 11. COM - PR EME D4 11. COM 3. How do mRNA codons determine their corresponding amino acids? (1.5 points) Key points needed in the answer: For each of the 20 different amino acids that are commonly found in proteins, there is a corresponding aminoacyl-tRNA synthetase that covalently links the amino acid to the tRNA molecule. Following the base pairing rule, the anticodon of the tRNA carrying the specific amino acid links to the corresponding mRNA codon through hydrogen bonds. ...
View Full Document

This document was uploaded on 10/27/2011 for the course BIL 250 at University of Miami.

Ask a homework question - tutors are online