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Mastering biology chapter 18 Flashcards

Mastering biology chapter 18
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  • What is the role of an operon in gene regulation?
    An operon is a cluster of genes under the control of a single promoter, allowing coordinated regulation.
  • How does the lac operon function in the presence of lactose?
    Lactose binds to the repressor, inactivating it and allowing transcription of the operon.
  • What is the function of a repressor protein?
    A repressor protein binds to the operator to block RNA polymerase and prevent transcription.
  • Define 'inducible operon' and give an example.
    An inducible operon is usually off but can be turned on by an inducer, like the lac operon.
  • What is the significance of the trp operon in bacteria?
    The trp operon is a repressible operon that controls the synthesis of tryptophan.
  • How does negative control of gene expression work?
    Negative control involves repressors that inhibit transcription when bound to DNA.
  • What is the role of an activator in gene regulation?
    An activator is a protein that increases gene transcription by binding to an enhancer or promoter.
  • Explain the concept of 'catabolite repression'.
    Catabolite repression is the inhibition of alternative carbon source metabolism when glucose is present.
  • What is the function of the CAP protein in the lac operon?
    CAP binds to the promoter to enhance RNA polymerase binding and transcription in the absence of glucose.
  • Describe the role of cAMP in the regulation of the lac operon.
    cAMP binds to CAP, allowing it to activate transcription of the lac operon.
  • What is an example of a repressible operon?
    The trp operon is an example of a repressible operon.
  • How does the presence of tryptophan affect the trp operon?
    Tryptophan activates the repressor, which binds to the operator and stops transcription.
  • What is the difference between positive and negative gene regulation?
    Positive regulation involves activators that increase transcription, while negative regulation involves repressors that decrease it.
  • What is the function of the operator in an operon?
    The operator is a DNA segment where a repressor binds to regulate transcription.
  • How does allolactose function in the lac operon?
    Allolactose is an inducer that inactivates the repressor, allowing transcription of the lac operon.
  • What is the role of RNA polymerase in transcription?
    RNA polymerase synthesizes RNA by following a DNA template during transcription.
  • Explain the concept of 'feedback inhibition' in metabolic pathways.
    Feedback inhibition is when the end product of a pathway inhibits an enzyme involved in its synthesis.
  • What is the function of a promoter in gene expression?
    A promoter is a DNA sequence where RNA polymerase binds to initiate transcription.
  • How does glucose affect the lac operon?
    Glucose presence reduces cAMP levels, decreasing CAP binding and lac operon transcription.
  • What is the role of the leader sequence in the trp operon?
    The leader sequence helps regulate transcription through attenuation based on tryptophan levels.