Molecular Biology Exam 2

83 Questions | Total Attempts: 687

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Molecular Biology Quizzes & Trivia

Cover chapter 6-13 for exam 2.


Questions and Answers
  • 1. 
    Which of the following is not present in the core RNA polymerase? 
    • A. 

      B (Beta)

    • B. 

      B' (Beta prime)

    • C. 

      Sigma (o)

    • D. 

      Both (Beta) and (sigma)

  • 2. 
    • A. 

      Include the RNA holoenzyme in the reaction.

    • B. 

      Use the core enzyme of RNA polymerase

    • C. 

      Enrich the preparation with sigma subunit

    • D. 

      Use intact DNA.

    • E. 

      Include the RNA holoenzyme in the reaction and use the core enzyme of RNA polymerase are both effective

  • 3. 
    Which of the following techniques would be most useful in testing the ability of the core RNA polymerase to bind to promoter? 
    • A. 

      Gel filtration

    • B. 

      S1 mapping

    • C. 

      Immunoblotting

    • D. 

      DNase footprinting

    • E. 

      Northern blotting

  • 4. 
    Which of the following statements is false regarding the sigma-factor? 
    • A. 

      It does not have a DNA-binding domain

    • B. 

      Interaction with the core enzyme unmasks the DNA-binding region

    • C. 

      Subregions 2.4 and 4.4 are involved in promoter recognition.

    • D. 

      It can also bind to the nontemplate strand.

    • E. 

      It can bind to the -10 box.

  • 5. 
    Which of the following is true about the holoenzyme of RNA pol in an open complex? 
    • A. 

      The DNA is bound mainly to the sigma-subunit

    • B. 

      There no interaction between the sigma factor and the -10 region.

    • C. 

      There are two Na+ ions in the core enzyme

    • D. 

      Region 2.4 of the sigma-factor binds the the -35 region.

    • E. 

      The DNA is bound mainly to the sigma-subunit and there no interaction between the sigma factor and the -10 region.

  • 6. 
    Dimethyl sulfate is used to 
    • A. 

      Cleave DNA molecules

    • B. 

      Denature or melt DNA promote region

    • C. 

      Remove methyl groups from RNA

    • D. 

      Add methyl groups to DNA

    • E. 

      Promote the binding of RNA polymerase to DNA

  • 7. 
    Which of the following would most likely occur if an in vitro transcription assay is preformed by using a cell extract containing an (alpha) a subunit without the C-terminal domain? 
    • A. 

      Polymerase would become tightly associated with the promoter

    • B. 

      Polymerase would become more susceptible to proteolysis

    • C. 

      Transcription will be accelerated

    • D. 

      Polymerase complex would be loosely associated with the promoter

    • E. 

      Recognition of the UP element would be faster

  • 8. 
    Place the following in the order that they occur during transcription initiation: 1- formation of open complex2- formation of closed complex3- promoter clearance4- synthesis of about 10 nucleotides 
    • A. 

      1,2,3,4

    • B. 

      2,1,4.3

    • C. 

      2,1,2,4

    • D. 

      3,1,2,4

    • E. 

      3,2,1,4

  • 9. 
    Which of the following techniques is suitable for the study of DNA:RNA hybrid formation during transcription? 
    • A. 

      DNA: protein crosslinking

    • B. 

      DNAase I footprinting

    • C. 

      DNA: RNA crosslinking

    • D. 

      Two-dimensional PAGE

    • E. 

      FRET analysis

  • 10. 
    Which of the following are characteristic of intrinsic terminator elements? 
    • A. 

      They contain an inverted repeat

    • B. 

      They contain a hairpin loop

    • C. 

      They contain several T's in the nontemplate strand of DNA

    • D. 

      Only they contain an inverted repeat and they contain a hairpin loop are correct

    • E. 

      They contain an inverted repeat, they contain a hairpin loop, and they contain several T's in the nontemplate strand of DNA.

  • 11. 
    Which of the following is incorrect regarding rho dependent terminators? 
    • A. 

      They contain several T's in the non-template strand

    • B. 

      They consist of inverted repeats

    • C. 

      They form hairpin loops

    • D. 

      Rho binds to the growing transcripts

    • E. 

      Rho has no helicase activity

  • 12. 
    Which of the following does not have a DNA-binding domain? 
    • A. 

      Sigma-factor

    • B. 

      UP region

    • C. 

      Alpha-factor

    • D. 

      Beta

    • E. 

      Beta prime

  • 13. 
    Which of the following bond is lactose links between glucose and galactose? 
    • A. 

      It is a glycoside bond

    • B. 

      The linkage is through (beta)-1, 4 bond

    • C. 

      It can be broken by (beta)-galactosidase

    • D. 

      It is a covalent bond

    • E. 

      All of the choices are correct

  • 14. 
    If an operon is under negative control it means that the operon is never operational
    • A. 

      True

    • B. 

      False

  • 15. 
    In the absence of glucose there will be a rapid accumulation of lactose in the following mutant: I- Oc Z+ Y-I- O+ Z+ Y-
    • A. 

      True

    • B. 

      False

  • 16. 
    The following is an example of a cis-dominant mutation: I-d O+ Z+ Y+ A-
    • A. 

      True

    • B. 

      False

  • 17. 
    Which of the following statements is true about a lac operon with the following genotype? I- Oc Z+ Y-I- O+ Z- Y-
    • A. 

      A repressor protein will be constitutively produced

    • B. 

      (Beta)- galactosidase will be constitutively produced

    • C. 

      A trans-dominant mutation is present

    • D. 

      Permease will be constitutively produced

    • E. 

      Both a repressor protein will be constitutively produced and a cis-dominant mutation is present

  • 18. 
    Which of the following plasmids could be used to restore inducible regulation of (Beta)-galatosidase in this mutatnt: I+ Oc Z- Y+ A+? 
    • A. 

      I+ Oc Z- Y+ A+

    • B. 

      I+Oc Z- Y- A-

    • C. 

      I- O+ Z+ Y+ A+

    • D. 

      I- Oc Z+ Y+ A+

    • E. 

      Both I+ Oc Z- Y+ A+ and I+ Oc Z- Y- A- are correct

  • 19. 
    Which of the following organisms would produce functional lac products in the presence of IPTG? 
    • A. 

      Is Oc Z- Y+ A+

    • B. 

      Is Oc Z- Y- A-

    • C. 

      I+ O+ Z+ Y+ A+

    • D. 

      I- Oc Z+ Y+ A+

    • E. 

      Both Is Oc Z- Y+ A+ and Is Oc Z- Y+ A+ are correct

  • 20. 
    Which of the followign statements is true about a lac operon with this genotype? I-d O+ Z+ Y- A- 
    • A. 

      The operon is repressible

    • B. 

      The operon is nonrepressible

    • C. 

      The mutation is cis-dominant

    • D. 

      The operon is uninducible

    • E. 

      None of the choices is correct

  • 21. 
    Which of the following techniques is most useful in determining if RNA polymerase has initiated transcription form the lac DNA template? 
    • A. 

      Southern analysis

    • B. 

      DNA fingerprinting

    • C. 

      Run-off transcription assay

    • D. 

      DNA sequencing

    • E. 

      RACE

  • 22. 
    In an in vitro transcription assay to detect the level of transcription from a lac operon, one of the RNA precursors was tagged with a fluorescent label on the y-phosphate. Which of the following is a likely outcome if transcription occurred? 
    • A. 

      The level of fluorescence would increase along the new RNA strand

    • B. 

      Each RNA would have a fluorescent tag on every other nucleotide.

    • C. 

      The level of fluorescence would be very high in the assay buffer

    • D. 

      No fluorescence would be detected in the buffer at the end of the assay

    • E. 

      All of the choices are possible

  • 23. 
    Which of the following is mostly likely to occur if the level of glucose is low in a bacterial cell? 
    • A. 

      Cyclic-AMP levels will be depressed

    • B. 

      CAP will assist in stimulating transcription of the lac operon if lactose is added

    • C. 

      CRP activity will be inhibited

    • D. 

      Both Cyclic-AMP levels will be depressed and CRP activity will be inhibited

    • E. 

      None of the choices is correct

  • 24. 
    • A. 

      CAP monomer binds directly tot he promoter stimulating polymerase to bind

    • B. 

      CAP-AMP blocks recruitment of polymerase to the promoter

    • C. 

      CAP blocks the (alpha) CTD of RNA polymerase

    • D. 

      Binding of the CAP-cAMP to thelac activator-binding site recruits RNA polymerase

    • E. 

      CAP monomer binds directly to the promoter stimulating polymerase to bind and CAP blocks the (alpha) CTD of RNA polymerase

  • 25. 
    Which of the following is true about the regulation of the trp operon? 
    • A. 

      An aporepressor is involved

    • B. 

      A corepressoris involved

    • C. 

      Attenuation is one of the control mechanisms.

    • D. 

      Negative control is involved

    • E. 

      All of the choices are true