Block 1 DNA-RNA Mini 1

27 Questions | Total Attempts: 468

SettingsSettingsSettings
Please wait...
Block 1 DNA-RNA Mini 1

Questions and Answers
  • 1. 
    • A. 

      Ubiquitination of histones H3 and H4 and increased overall transcription

    • B. 

      Fragmentation of poorly protected chromosomal DNA and reduced transcription

    • C. 

      Activation of histone H3 and H4 gene expression

    • D. 

      Reduced transcription rates because nucleosomes occupy promoters

    • E. 

      Uncoupling of transcription and translation in neurons

  • 2. 
    DNA contains which one of the following components?
    • A. 

      Nitrogenous bases joined by phosphodiester bonds

    • B. 

      Negatively charged phosphate groups in the interior of the molecule

    • C. 

      Base pairs stacked along the exterior of the molecule

    • D. 

      Two strands that run in the opposite direction

    • E. 

      The sugar ribose

  • 3. 
    When synthesis of segment C begins, which other segment is also being synthesized?  
    • A. 

      A

    • B. 

      B

    • C. 

      C

    • D. 

      D

    • E. 

      E

  • 4. 
    • A. 

      DUTP

    • B. 

      UTP

    • C. 

      DTTP

    • D. 

      TTP

    • E. 

      DTMP

  • 5. 
    Which of the following phrases describes nucleosomes?
    • A. 

      Single ribosomes attached to mRNA

    • B. 

      Complexes of DNA and all the histones except H4

    • C. 

      Subunits of chromatin

    • D. 

      Structures that contain DNA in the core with histones wrapped around the surface

    • E. 

      Complexes of protein and the 45S rRNA precursors found in the nucleolus

  • 6. 
    Which one of the following point mutations would NOT produce a change in the protein translated from an mRNA?
    • A. 

      UCA → UAA

    • B. 

      UCA → CCA

    • C. 

      UCA → UCU

    • D. 

      UCA → ACA

    • E. 

      UCA → GCA

  • 7. 
    Tetracycline, streptomycin, and erythromycin are effective antibiotics because they inhibit
    • A. 

      RNA synthesis in prokaryotes

    • B. 

      RNA synthesis in eukaryotes

    • C. 

      Protein synthesis in prokaryotes

    • D. 

      Protein synthesis on cytoplasmic ribosomes of eukaryotes

    • E. 

      Protein synthesis on mitochondrial ribosomes of prokaryotes

  • 8. 
    When this in vitro protein-synthesizing system was treated with the new antibiotic, the only product was methionyl-phenylalanyltRNA.  What process in protein synthesis is inhibited by the antibiotic?
    • A. 

      Binding of an aminoacyl-tRNA to the A site of the ribosome

    • B. 

      Initiation

    • C. 

      Translocation

    • D. 

      Peptidyl transferase catalyzed formation of a peptide bond

  • 9. 
    A double-stranded RNA genome isolated from a virus in the stool of a child with gastroenteritis was found to contain 15 % uracil.  What is the percentage of guanine in this genome?
    • A. 

      15

    • B. 

      25

    • C. 

      35

    • D. 

      75

    • E. 

      85

  • 10. 
    It is now believed that a substantial proportion of the single nucleotide substitutions causing human genetic disease are due to misincorporation of bases during DNA replication.  Which proofreading activity is critical in determining the accuracy of nuclear DNA replication and thus the base substitution mutation rate in human chromosomes?
    • A. 

      3’ to 5’ polymerase activity of DNA polymerase δ

    • B. 

      3’ to 5’ exonuclease activity of DNA polymerase γ

    • C. 

      Primase activity of DNA polymerase α

    • D. 

      5’ to 3’ polymerase activity of DNA polymerase δ

    • E. 

      3’ to 5’ exonuclease activity of DNA polymerase δ

  • 11. 
    The proliferation of cytotoxic T-cells is markedly impaired upon infection with a newly discovered human immunodeficiency virus, designated HIV-V.  The defect has been traced to the expression of a viral-encoded enzyme that inactivates a host-cell nuclear protein required for DNA replication.  Which protein is a potential substrate for the viral enzyme?
    • A. 

      TATA-box binding protein (TBP)

    • B. 

      Cap binding protein (CBP)

    • C. 

      Catabolite activator protein (CAP)

    • D. 

      Acyl-carrier protein (ACP)

    • E. 

      Single-strand binding protein (SBP)

  • 12. 
    The anti-Pseudomonas action of norfloxacin is related to its ability to inhibit chromosome duplication in rapidly dividing cells.  Which of the following enzymes participates in bacterial DNA replication and is directly inhibited by this antibiotic?
    • A. 

      DNA polymerase I

    • B. 

      DNA polymerase II

    • C. 

      Topoisomerase I

    • D. 

      Topoisomerase II

    • E. 

      DNA ligase

  • 13. 
    Enhancers are transcriptional regulatory sequences that function by enhancing the activity of
    • A. 

      General transcriptional factors

    • B. 

      RNA polymerase to enable the enzyme to transcribe through the terminating region of a gene

    • C. 

      Transcription factors that bind to the promoter but not to RNA polymerase

    • D. 

      RNA polymerase at a single promoter site

    • E. 

      Spliceosomes

  • 14. 
    A gene encodes a protein with 150 amino acids.  There is one intron of 1,000 bp, a 5’-untranslated region of 100 bp, and a 3’-untranslated region of 200 bp.  In the final processed mRNA, how many bases lie between the start AUG codon (include the start codon) and the final termination codon?
    • A. 

      1,750

    • B. 

      750

    • C. 

      650

    • D. 

      450

    • E. 

      150

  • 15. 
    A messenger RNA is 336 nucleotides long, including the initiator and termination codons. The number of amino acids in the protein translated from this mRNA is:
    • A. 

      999

    • B. 

      630

    • C. 

      330

    • D. 

      111

    • E. 

      110

  • 16. 
    You have obtained a sample of DNA, and you transcribe mRNA from this DNA and purify it. You then separate the two strands of the DNA and analyze the base composition of each strand and of the mRNA. You obtain the data shown in the table to the right. Which strand of the DNA is the coding strand, serving as a template for mRNA synthesis?
    • A. 

      Strand 1

    • B. 

      Strand 2

    • C. 

      Both strands 1 and 2

    • D. 

      Neither strand 1 nor 2

    • E. 

      Too little information to tell

  • 17. 
    Given that the LD50 (the dose of which 50% of the recipients die) of amanitin is 0.1 mg per kg body weight, and that the average mushroom contains 7 mg amanitin, how many mushrooms must be consumed by someone who is 100 kg to be above the LD50?
    • A. 

      1

    • B. 

      2

    • C. 

      3

    • D. 

      4

    • E. 

      5

  • 18. 
    If a 1,000-kilobase fragment of DNA has 10 evenly spaced and symmetric replication origins and DNA polymerase moves at 1 kilobase per second, how many seconds will it take to produce two daughter molecules (ignore potential problems at the ends of this linear piece of DNA)?  Assume that the 10 origins are evenly spaced from each other, but not from the ends of the chromosome.
    • A. 

      20

    • B. 

      30

    • C. 

      40

    • D. 

      50

    • E. 

      100

  • 19. 
    In eukaryotes, histone acetylation is typically associated with:
    • A. 

      Gene activation

    • B. 

      Gene inactivation

    • C. 

      Transposition

    • D. 

      Translation

    • E. 

      Protein secretion

  • 20. 
    The following piece of DNA is being replicated. The replication fork moves from left to right along this DNA. What is the sequence of an Okazaki fragment on this piece of DNA whose 5’ and 3’ ends are located right at the borders of the shown sequence?
    • A. 

      5’ AGGTGCATGATAACATCC 3’

    • B. 

      5’ CCTACAATAGTACGTGGA 3’

    • C. 

      5’ TCCACGTACTATTGTAGG 3’

    • D. 

      5’ GGATGTTATCATGCACCT 3’

    • E. 

      5’ GGATGTTATTATTGTAGG 3’

  • 21. 
    The average size of a human gene is
    • A. 

      1,000 bp

    • B. 

      40,000 bp

    • C. 

      2 x 106 bp

    • D. 

      1.5 x 108 bp

    • E. 

      3 x 109 bp

  • 22. 
    • A. 

      DNA-directed DNA polymerase

    • B. 

      Unwinding proteins

    • C. 

      DNA polymerase I

    • D. 

      DNA-directed RNA polymerase

    • E. 

      DNA ligase

  • 23. 
    If a completely radioactive double-stranded DNA molecule undergoes two rounds of replication in a solution free of radioactive label, what is the radioactivity status of the resulting four double-stranded DNA molecules?
    • A. 

      Half should contain no radioactivity

    • B. 

      All should contain radioactivity

    • C. 

      Half should contain radioactivity in both strands

    • D. 

      One should contain radioactivity in both strands

    • E. 

      None should contain radioactivity

  • 24. 
    The hypothetical “stimulin” gene contains two exons that encode a protein of 100 amino acids.  They are separated by an intron of 100 bp beginning after the codon for amino acid 10.  Stimulin messenger RNA (mRNA) has 5’ and 3’ untranslated regions of 70 and 30 nucleotides, respectively.  A complementary DNA (cDNA) made from mature stimulin RNA would have which of the following sizes?
    • A. 

      500 bp

    • B. 

      400 bp

    • C. 

      300 bp

    • D. 

      100 bp

    • E. 

      70 bp

  • 25. 
    An immigrant from Eastern Europe is rushed into the emergency room with nausea, vomiting, diarrhea, and abdominal pain.  His family indicates he has eaten wild mushrooms.  They have brought a bag of fresh, uncooked mushrooms from a batch he had not yet prepared.  You note the presence of Amanita phalloides, the death-cap mushroom.  Care is supportive.  A major toxin of the death-cap mushroom is the hepatotoxic octapeptide a-amanitin, which inhibits
    • A. 

      DNA primase

    • B. 

      RNA nuclease

    • C. 

      DNA ligase

    • D. 

      RNA polymerase

    • E. 

      RNA/DNA endonuclease

  • 26. 
    The DNA sequence M, shown below, is the sense strand from a coding region known to be mutational “hot spot” for a gene.  It encodes amino acids 21-25.  Given the genetic and amino acid codes CCC = proline (P), GCC = alanine (A), TTC = phenylalanine (F), and TAG = stop codon, which of the following sequences is a frame-shift mutation that causes termination of the encoded protein?   M 5’-CCC-CCT-AGG-TTC-AGG-3’
    • A. 

      -CCA-CCT-AGG-TTC-AGG-

    • B. 

      -GCC-CCT-AGG-TTC-AGG-

    • C. 

      -CCA-CCC-TAG-GTT-CAG-

    • D. 

      -CCC-CTA-GGT-TCA-GG- -

    • E. 

      -CCC-CCT-AGG-AGG- - -

  • 27. 
    Erythromycin is the antibiotic of choice when treating respiratory tract infections in legionnaire’s disease, whooping cough, and Mycoplasma-based pneumonia because of its ability to inhibit protein synthesis in certain bacteria by
    • A. 

      Inhibiting translocation by binding to 50S ribosomal subunits

    • B. 

      Acting as an analogue of mRNA

    • C. 

      Causing premature chain termination

    • D. 

      Inhibiting initiation

    • E. 

      Mimicking mRNA binding