ch 18

24 Questions  I  By Grtnb
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Ch 18

  
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  • 1. 
    What does the operon model attempt to explain?
    • A. 

      Bacterial resistance to antibiotics

    • B. 

      How genes move between homologous regions of DNA

    • C. 

      The coordinated control of gene expression in bacteria

    • D. 

      The mechanism of viral attachment to a host cell

    • E. 

      Horizontal transmission of plant viruses


  • 2. 
    The role of a metabolite that controls a repressible operon is to
    • A. 

      Bind to the promoter region and decrease the affinity of RNA polymerase for the promoter

    • B. 

      Bind to the repressor protein and activate it

    • C. 

      Bind to the repressor protein and inactivate it

    • D. 

      Bind to the operator region and block the attachment of RNA polymerase to the promoter

    • E. 

      Increase the production of inactive repressor proteins


  • 3. 
    The tryptophan operon is a repressible operon that is
    • A. 

      Permanently turned on

    • B. 

      Turned on only when typtophan is present in the growth medium

    • C. 

      Turned on only when glucose is present in the growth medium

    • D. 

      Turned off whenever tryptophan is added to the growth medium

    • E. 

      Turned off only when glucose is present in the growth medium


  • 4. 
    This protein is produced by a regulatory gene
    • A. 

      Operon

    • B. 

      Inducer

    • C. 

      Promotor

    • D. 

      Repressor

    • E. 

      Corepressor


  • 5. 
    A mutation in this section of DNA could influence the binding of RNA polymerase to the DNA
    • A. 

      Operon

    • B. 

      Inducer

    • C. 

      Promoter

    • D. 

      Repressor

    • E. 

      Corepressor


  • 6. 
    A lack of this nonprotein molecule would result in the inability of the cell to "turn off" genes
    • A. 

      Operon

    • B. 

      Inducer

    • C. 

      Promoter

    • D. 

      Repressor

    • E. 

      Corepressor


  • 7. 
    When this is taken up by the cell, it binds to the repressor so that the repressor no longer binds to the operator
    • A. 

      Operon

    • B. 

      Inducer

    • C. 

      Promoter

    • D. 

      Repressor

    • E. 

      Corepressor


  • 8. 
    For a repressible operon to be transcribed, which of the following must occur?
    • A. 

      A corepressor must be present

    • B. 

      RNA polymerase and the active repressor must be present

    • C. 

      RNA polymerase must bind to the promoter, and the respressor must be inactive

    • D. 

      RNA polymerase cannot be present, and the repressor must be inactive

    • E. 

      RNA polymerase must not occupy the promoter, and the repressor must be inactive


  • 9. 
    If glucose is available in the environment of E.coli, the cell responds with very low concentration of cAMP. When the cAMP increases in concentration, it binds to CAP. Which of the following would you expect would then be a measurable effect?
    • A. 

      Decreased concentration of the lac enzymes

    • B. 

      Increased concentration of the trp enzymes

    • C. 

      Decreased binding of the RNA polymerase to sugar metabolism - related promoters

    • D. 

      Decreased concentration of alternative sugars in the cell

    • E. 

      Increased concentration of sugars such as arabinose in the cell


  • 10. 
    Two potential devices that eukaryotic cells use to regulate transcription are
    • A. 

      DNA methylation and histone amplification

    • B. 

      DNA amplification and histone methylation

    • C. 

      DNA acetylation and methylation

    • D. 

      DNA methylation and histone acetylation

    • E. 

      Histone amplification and DNA acetylation


  • 11. 
    This binds to a site in the DNA far from the promoter to stimulate transcription
    • A. 

      Enhancer

    • B. 

      Promoter

    • C. 

      Activator

    • D. 

      Repressor

    • E. 

      Terminator


  • 12. 
    This can inhibit transcription by blocking the binding of positively acting transcription factors to the DNA
    • A. 

      Enhancer

    • B. 

      Promoter

    • C. 

      Activaor

    • D. 

      Repressor

    • E. 

      Terminator


  • 13. 
    This is the site in the DNA located near the end of the final exon, encoding an RNA sequence that determines the 3' end of the transcript
    • A. 

      Enhancer

    • B. 

      Promoter

    • C. 

      Activator

    • D. 

      Repressor

    • E. 

      Terminator


  • 14. 
    A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. In one set of experiments using this procedure in Drosophila, she was readily successful in increasing phosphorylation of amino acids adjacent to methylated amino acids in histone tails. Which of the following results would she most likely see?
    • A. 

      Increased chromatin condensation

    • B. 

      Decreased chromatin concentration

    • C. 

      Abnormalities of mouse embryos

    • D. 

      Decreased binding of transcription factors

    • E. 

      Inactivation of the selected genes


  • 15. 
    A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. In one set of experiments she succeeded in decreasing methylation of histone tails. Which of the following results would she most likely see?
    • A. 

      Increased chromatin condensation

    • B. 

      Decreased chromatin concentration

    • C. 

      Abnormalities of mouse embryos

    • D. 

      Decreased binding of transcription factors

    • E. 

      Inactivation of the selected genes


  • 16. 
    A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. One of her colleagues suggested she try increased methylation of C nucleotides in a mammalian system. Which of the following results would she most likely see?
    • A. 

      Increased chromatin condensation

    • B. 

      Decreased chromatin concentration

    • C. 

      Abnormalities of mouse embryos

    • D. 

      Decreased binding of transcription factors

    • E. 

      Inactivation of the selected genes


  • 17. 
    A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. She tried decreasing the amount of methylation enzymes in the embryonic stem cells and then allowed the cells to further differentiate. Which of the following results would she most likely see?
    • A. 

      Increased chromatin condensation

    • B. 

      Decreased chromatin concentration

    • C. 

      Abnormalities of mouse embryos

    • D. 

      Decreased binding of transcription factors

    • E. 

      Inactivation of the selected genes


  • 18. 
    Gene expression might be altered at the level of post-transcriptional processing in eukaryotes rather than prokaryotes because of which of the following?
    • A. 

      Eukaryotic mRNAs get 5ʹ caps and 3ʹ tails.

    • B. 

      Prokaryotic genes are expressed as mRNA, which is more stable in the cell.

    • C. 

      Eukaryotic exons may be spliced in alternative patterns.

    • D. 

      Prokaryotes use ribosomes of different structure and size.

    • E. 

      Eukaryotic coded polypeptides often require cleaving of signal sequences before localization.


  • 19. 
    Which of the following statements describes proto-oncogenes?
    • A. 

      They are introduced to a cell initially by retroviruses.

    • B. 

      They are produced by somatic mutations induced by carcinogenic substances

    • C. 

      Their normal function is to suppress tumor growth

    • D. 

      They can code for proteins associated with cell growth.

    • E. 

      They are underexpressed in cancer cells


  • 20. 
    Which of the following is characteristic of the product of the p53 gene?
    • A. 

      It speeds up the cell cycle

    • B. 

      It causes cell death via apoptosis

    • C. 

      It is an activator for other genes

    • D. 

      It allows cells to pass on mutations due to DNA damage

    • E. 

      It slows down the rate of DNA replication by interfering with the binding of DNA polymerase


  • 21. 
    Altering patterns of gene expression in prokaryotes would most likely serve the organismʹs survival in which of the following ways?
    • A. 

      Organizing gene expression so that genes are expressed in a given order

    • B. 

      Allowing each gene to be expressed an equal number of times

    • C. 

      Allowing environmental changes to alter the prokaryoteʹs genome

    • D. 

      Allowing the organism to adjust to changes in environmental conditions

    • E. 

      Allowing young organisms to respond differently from more mature org


  • 22. 
    In response to chemical signals, prokaryotes can do which of the following?
    • A. 

      Turn off translation of their mRNA

    • B. 

      Alter the level of production of various enzymes

    • C. 

      Increase the number and responsiveness of their ribosomes

    • D. 

      Inactivate their mRNA molecules

    • E. 

      Alter the sequence of amino acids in certain proteins


  • 23. 
    Steroid hormones produce their effects in cells by
    • A. 

      Activating key enzymes in metabolic pathways

    • B. 

      Activating translation of certain mRNAs

    • C. 

      Promoting the degradation of specific mRNAs

    • D. 

      Promoting the formation of looped domains in certain regions of DNA.

    • E. 

      Binding to intracellular receptors and promoting transcription of specific genes


  • 24. 
    Forms of the ras protein found in tumors usually cause which of the following?
    • A. 

      Cell-to-cell adhesion to be nonfunctional

    • B. 

      Growth factor signaling to be hyperactive

    • C. 

      DNA replication to stop

    • D. 

      DNA replication to be hyperactive

    • E. 

      Cell division to cease


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