18

Last update by Shanal on 11/06/2013
156555 People have viewed this Quiz
  • Share

8) A mutation that inactivates the regulatory gene of a repressible operon in an E. coli cell would result in

A) continuous transcription of the structural gene controlled by that regulator.

B) complete inhibition of transcription of the structural gene controlled by that regulator.

C) irreversible binding of the repressor to the operator.

D) inactivation of RNA polymerase by alteration of its active site.

E) continuous translation of the mRNA because of alteration of its structure.

Answer:

A) continuous transcription of the structural gene controlled by that regulator.

View 18 as Flashcard Deck

Related Quiz Content
  • boydstun 3
    Answered in 18

    9) The lactose operon is likely to be transcribed when

    A) there is more glucose in the cell than lactose.

    B) the cyclic AMP levels are low.

    C) there is glucose but no lactose in the cell.

    D) the cyclic AMP and lactose levels are both high within the cell.

    E) the cAMP level is high and the lactose level is low.

    D) the cyclic AMP and lactose levels are both high within the cell.

  • boydstun 3
    Answered in 18

    10) Transcription of the structural genes in an inducible operon

    A) occurs continuously in the cell.

    B) starts when the pathway's substrate is present.

    C) starts when the pathway's product is present.

    D) stops when the pathway's product is present.

    E) does not result in the production of enzymes.

    B) starts when the pathway's substrate is present.

  • boydstun 3
    Answered in 18

    11) How does active CAP induce expression of the genes of the lactose operon?

    A) It terminates production of repressor molecules.

    B) It degrades the substrate allolactose.

    C) It stimulates splicing of the encoded genes.

    D) It stimulates the binding of RNA polymerase to the promoter.

    E) It binds steroid hormones and controls translation.

    D) It stimulates the binding of RNA polymerase to the promoter.

  • boydstun 3
    Answered in 18

    12) 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 repressor 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.

    C) RNA polymerase must bind to the promoter, and the repressor must be inactive.

  • boydstun 3
    Answered in 18

    13) Allolactose induces the synthesis of the enzyme lactase. An E. coli cell is presented for the first time with the sugar lactose (containing allolactose) as a potential food source. Which of the following occurs when the lactose enters the cell?

    A) The repressor protein attaches to the regulator.

    B) Allolactose binds to the repressor protein.

    C) Allolactose binds to the regulator gene.

    D) The repressor protein and allolactose bind to RNA polymerase.

    E) RNA polymerase attaches to the regulator.

    B) Allolactose binds to the repressor protein.

  • boydstun 3
    Answered in 18

    14) Altering patterns of gene expression in prokaryotes would most likely serve the organism's 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 the organism to adjust to changes in environmental conditions

    D) allowing young organisms to respond differently from more mature organisms

    E) allowing environmental changes to alter the prokaryote's genome

    C) allowing the organism to adjust to changes in environmental conditions

  • boydstun 3
    Answered in 18

    15) 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

    B) alter the level of production of various enzymes

  • boydstun 3
    Answered in 18

    16) If she moves the promoter for the lac operon to the region between the beta galactosidase gene and the permease gene, which of the following would be likely?

    A) Three structural genes will no longer be expressed.

    B) RNA polymerase will no longer transcribe permease.

    C) The operon will no longer be inducible.

    D) Beta galactosidase will not be produced.

    E) The cell will continue to metabolize but more slowly.

    D) Beta glycolase will not be produced.

  • boydstun 3
    Answered in 18

    17) If she moves the operator to the far end of the operon (past the transacetylase gene), which of the following would likely occur when the cell is exposed to lactose?

    A) The inducer will no longer bind to the repressor.

    B) The repressor will no longer bind to the operator.

    C) The operon will never be transcribed.

    D) The structural genes will be transcribed continuously.

    E) The repressor protein will no longer be produced.

    D) The structural genes will be transcribed continuously.

  • boydstun 3
    Answered in 18

    18) If she moves the repressor gene (lac I), along with its promoter, to a position at some several thousand base pairs away from its normal position, which will you expect to occur?

    A) The repressor will no longer be made.

    B) The repressor will no longer bind to the operator.

    C) The repressor will no longer bind to the inducer.

    D) The lac operon will be expressed continuously.

    E) The lac operon will function normally.

    E) The lac operon will function normally.

  • boydstun 3
    Answered in 18

    19) 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 concentrations of sugars such as arabinose in the cell

    E) increased concentrations of sugars such as arabinose in the cell