Nucleic acid synthesis and metabolism.


  1. DNA can be synthesized by the enzyme

    RNA polymerase on an RNA template.

    DNA polymerase on a DNA template.

    reverse transcriptase on a DNA or RNA template.

    terminal transferase in a template-independent manner.


  2. Synthesis of DNA on a template occurs occurs by a mechanism that is

    primer-dependent and proceeds in a 5´ to 3´ orientation.

    primer-independent and proceeds in a 5´ to 3´ orientation.

    primer-dependent and proceeds in a 3´ to 5´ orientation.

    primer-independent and proceeds in a 3´ to 5´ orientation.

    primer-dependent and proceeds in either orientation.


  3. DNA polymerase I purified from the bacterium Escherichia coli has which of the following enzymatic activities:

    5´->3´ DNA polymerase only.

    3´->5´ DNA polymerase only.

    5´->3´ DNA polymerase, 5´->3´ exonuclease, and 3´->5´ exonuclease.

    5´->3´ DNA polymerase and 3´->5´ exonuclease.


  4. Klenow fragment of DNA polymerase I purified from the bacterium Escherichia coli has which of the following enzymatic activities:

    5´->3´ DNA polymerase only.

    3´->5´ DNA polymerase only.

    5´->3´ DNA polymerase, 5´->3´ exonuclease, and 3´->5´ exonuclease.

    5´->3´ DNA polymerase and 3´->5´ exonuclease.


  5. Nicks in a double-stranded DNA molecule can be repaired by

    DNA topoisomerase.

    DNA polymerase I.

    DNA ligases.

    polynucleotide kinase.

    alkaline phosphatase.


  6. The ability of a bacterial RNA polymerase to initiate transcription on a DNA template at a specific sequence refered to as a promoter appears to be conferred by which subunit?

    Rho.

    Beta.

    Beta prime.

    Alpha.

    Sigma.


  7. Although both RNA and DNA polymerase can initiate polynucleotide synthesis on a DNA template, a major difference between these enzymes is

    the ability of RNA polymerase to initiate synthesis in the absence of a primer.

    the rapid conversion of the deoxynucleoside triphosphates to ribonucleosides by RNA polymerase during the synthesis reaction.

    the great difference in energy consumed by these two types of enzyme during the corresponding elongation reactions.

    the ease with which the specificity of the RNA polymerase reaction can be reproduced in a test tube, compared to the difficulty of working with purified DNA polymerase.


  8. A very significant difference between E. coli DNA ligase and T4 DNA ligase is

    the ability of only T4 DNA ligase to ligate non- phosphorylated termini.

    the ability of only the E. coli enzyme to ligate overlapping 5´ cohesive DNA termini.

    the ability of only T4 DNA ligase to ligate non-cohesive, or blunt-end, termini.

    the ability of only T4 DNA ligase to ligate overlapping 3´- cohesive termini.


  9. The most common use of the enzyme reverse transcriptase is for

    primer-independent synthesis of DNA on a DNA template

    primer-independent synthesis of DNA on an RNA template

    primer-dependent synthesis of DNA on a DNA template

    primer-dependent synthesis of DNA on an RNA template


  10. Treatment of a DNA fragment with the enzyme alkaline phosphatase will prevent the use of the fragmant as a good template for the reaction performed by

    DNA polymerase.

    RNA polymerase.

    restriction endonucleases.

    DNA ligases.


  11. The primary activity of S1 nuclease is

    sequence-specific cleavage of RNA.

    sequence-specific cleavage of DNA.

    cleavage of single-stranded regions of DNA or RNA.

    cleavage of single-stranded regions of DNA only.


  12. Sequence-specific cleavage of a DNA template can be accomplished by

    recA protein.

    nuclease BAL-31.

    restriction endonuclease.

    DNA topoisomerase.


  13. Typical features of type II restriction endonucleases include

    fairly small recognition sequences.

    two-fold rotational symmetry.

    requirement of an energy source like ATP or SAM.

    complex protein structure involving multiple subunits.


  14. Treatment of a DNA fragment with a modification methylase will prevent the use of that fragment as an effective substrate for

    DNA polymerase.

    any restriction endonuclease.

    the corresponding restriction endonuclease with the same recognition specificity.

    DNA ligase.


  15. Cleavage of the DNA at a restriction endonuclease recognition site can occur

    at the 5´ side of the center of the recognition site.

    at the center of the recognition site.

    at the 3´ side of the center of the recognition site.

    outside of the recognition site.


  16. Thermostable DNA polymerases like Taq DNA polymerase are very different from most bacterial DNA polymerases because of

    their ability to use any primed DNA as a template.

    their lack of requirement for a DNA primer for synthesis to occur.

    their ability to easily be purified to a very pure and active state.

    their ability to continue the polymerization reaction at very high temperatures that inactivate most other enzymes.


  17. The RNA portion of a double-stranded RNA:DNA hybrid molecule can generally be degraded by

    the enzyme RNAse H.

    any ribonuclease.

    S1 nuclease.

    alkaline conditions (>pH10).


  18. Isoschizomers are

    restriction enzymes that have been isolated from the same organism but cleave DNA at different sequences.

    restriction enzymes that have been isolated from different organisms but cleave DNA at the same sequence.

    restriction enzymes that recognize and cleave at the same DNA sequence but differ in their inhibition by methylation pattern within the recognition sequence.

    Two different oligonucleotide sequences that are similar enough to anneal with a common target DNA sequence.


  19. The enzyme terminal transferase

    transfers the terminal phosphate residue from ATP to the 5´ hydroxyl of DNA.

    transfers the terminal phosphate residue from ATP to the 3´ hydroxyl of DNA.

    extends the 5´ terminus of a DNA fragment by adding dNTP's in a template-independent manner.

    extends the 3´ terminus of a DNA fragment by adding dNTP's in a template-independent manner.


  20. Exonuclease III will degrade DNA

    from the 5´ phosphate of a recessed 5´ end in a 5´ to 3´ direction.

    from the 3´ hydroxyl of a recessed 3´ end in a 3´ to 5´ direction.

    only when the DNA is a single-stranded fragment.

    Only at places where there are mismatched bases in the heteroduplex.

    ©1999 Attotron Biosensor Corporation
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