Gene Regulation

Gene Regulation

  • Gene Regulation: The process of controlling gene expression, which affects protein production in cells.

Core Concepts

  • All Cells in Multicellular Organisms:

    • Contain the same DNA.
    • Different cell types arise due to differences in gene expression.

  • How is Gene Expression Regulated?:

    • Transcriptional Control: The primary level of control for protein production.

Gene Regulatory Proteins

  • Cells contain gene regulatory proteins that modulate transcription by binding to specific DNA sequences:
    • Repressors:
    • Function to turn genes off by hindering RNA polymerase activity.
    • Activators:
    • Help turn genes on by assisting in the recruitment of RNA polymerase.

Example: Lac Operon in E. coli

  • The Lac operon is an example of gene regulation:
    • Contains two gene regulatory proteins: an activator and a repressor.
    • Controls the transcription of several genes responsible for the import and metabolism of lactose.
    • Factors influencing the operon:
    • Repressor Presence: Activates when there is no lactose.
    • Activator Presence: Requires glucose to be absent for lactose utilization.

Eukaryotic Gene Expression

  • More complex than in prokaryotes:

    • Includes
    • mRNA synthesis that necessitates general transcription factors for RNA polymerase to bind to promoters.
    • Enhancer sequences that regulatory factors bind to for transcription control.

  • Key Elements:

    • Multiple Gene Regulatory Proteins:
    • Many genes require combinations of several regulatory proteins for transcription to succeed.
    • Combinatorial Control: Use of multiple regulatory proteins to fine-tune gene expression.

  • DNA Packing and Gene Expression:

    • Higher levels of DNA packing/condensation decrease transcription levels.

Eukaryotic Gene Regulatory Examples

  • Hormonal Influence:

    • Hormones bind to transcription factors (e.g., glucocorticoid receptor).
    • GR activation influences the expression of specific genes in particular cell types.

  • Master Regulatory Genes:

    • Example: MyoD gene
    • Involved in muscle cell production.
    • Example: Pax6 gene
    • Plays a vital role in eye development.

  • General Summary:

    • Gene regulation involves complex mechanisms that govern which genes are expressed in different cell types, influencing cell differentiation and function.