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Biology LibreTexts

12.S: Regulation of Gene Expression (Summary)

  • Page ID
    4162
  • [ "article:topic", "authorname:tnickle" ]

    • Regulation of gene expression is essential to the normal development and efficient functioning of cells
    • Gene expression may be regulated by many mechanisms, including those affecting transcript abundance, protein abundance, and post-translational  modifications
    • Regulation of transcript abundance may involve controlling the rate of initiation and elongation of transcription, as well as transcript splicing, stability, and turnover
    • The rate of initiation of transcription is related to the presence of RNA polymerase and associated proteins at the promoter. 
    • RNApol may be blocked from the promoter by repressors, or may be recruited or stabilized at the promoter by other proteins including transcription factors
    • The lac operon is a classic, fundamental paradigm demonstrating both positive and negative regulation through allosteric effects on trans-factors.
    • In eukaryotes, cis-elements that are usually called enhancers bind to specific trans-factors to regulate transcriptional initiation. 
    • Enhancers may be modular, with each enhancer and its transcription factor regulating a distinct component of a gene’s expression pattern, as in the yellow gene.
    • Sticklebacks provide examples of recent evolutionary events in which mutation of an enhancer produced a change in morphology and a selective advantage.
    • Chromatin structure, including reversible modifications such as acetylation of histones, and methylation DNA CpG sites also regulates the initiation of transcription.
    • Chromatin modifications or DNA methylation of some genes are heritable over many mitotic, and sometimes even meiotic divisions.
    • Heritable changes in phenotype that do not result from a change in DNA sequence are called epigenetic.  Many epigenetic phenomena involve regulation of gene expression by chromatin modification and/or DNA methylation.

    Key Terms:

    gene expression

    transcriptional regulation

    operon

    lactose

    glucose

    lac operon

    lacZ

    lacY

    lacA

    galactosidase

    permease

    trans-acetylase

    P  /  promoter

    O  /  operator

    CBS

    CAP-binding site

    cis-elements

    trans-regulators

    lacI

    homotetramer

    repressor

    allosteric

    cAMP binding protein

    CAP

    CAP binding sequence

    CBS

    adenylate cyclase

    constitutive

    Oc  /  I-   /   Is

    F-factor / episome

    GC boxes

    CAAT boxes

    TATA boxes

    GAL4-UAS

    Driver/responder

    transcription start site

    enhancers/silencers

    transcription factors

    hemoglobin/heme/globin

    pseudogene

    gene families

    stickleback

    primordium

    chromatin remodeling

    acetylation/deacetylation

    methylation/demethylation

    CpG sites

    epigenetics

    winter annual

    vernalization

    FLC

     

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