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Gene Expression Regulation Overview

Notes

Gene Expression Regulation Overview

Sections

GENE EXPRESSION REGULATION OVERVIEW

  • Allows organisms to be more efficient with resources and to adapt to the environment
  • Important for cell differentiation (which results in many different cell types)

STEPS REGULATION OCCURS

  1. Transcriptional Control
  • When and how often a gene is transcribed
  • Only point where the cell will not synthesize unneeded intermediates, thereby wasting resources
  1. RNA Processing Control
  • Control of the splicing and processing of RNA transcripts
  1. RNA Transport and Localization Control
  • Cells select which mRNAs are exported to the cytoplasm and where they are localized to
  1. Translational Control
  • Control which mRNAs get translated into protein
  1. mRNA Degradation Control
  • Cells can destabilize specific mRNAs in the cytoplasm to limit protein production
  1. Protein Activity Control
  • Cells can selectively activate, inactivate, localize or degrade proteins after they have been synthesized

Full-Length Text

  • Here we will learn about the ways in which gene expression is regulated, which allows a cell to control how much and what kinds of protein it makes.
  • First, start a table to denote some key concepts of gene expression regulation.
  • Denote that regulating the expression of genes allows organisms to be more efficient with their resources and adaptive to their environment.
    • For example, there is no need for a bacterium to synthesize the enzymes necessary to break down lactose into energy when there is no lactose around.
  • Denote that gene regulation is especially important for multicellular organisms that have many different types of cells present.
    • Each cell has a complete copy of the genome but each type of cell does not need to use every protein, so regulation is necessary.
  • Denote that cell differentiation is the process during development which results in many different cell types.

Now let's explore the path from DNA to protein and take note where regulation occurs.

  • First, draw the nuclear envelope.
  • Label the nucleus and the cytoplasm.
  • Label the nuclear pore.
  • Within the nucleus, draw DNA.
    • Recall that DNA is transcribed into RNA.
  • Draw the RNA.
    • RNA then undergoes post-transcriptional modification to become mRNA.
  • Draw the mRNA.
  • Label the 5' cap and the poly-A tail.
    • Mature mRNA is then exported out of the nucleus and into the cytoplasm through the nuclear pore.
  • Draw the mRNA in the cytoplasm.
    • mRNA is then translated into protein.
  • Draw the protein.
    • Synthesized proteins often require activation.
  • Draw the activated protein.
    • From here, the protein goes on to do its job.

Regulation of proteins can occur at each step of this pathway. We discuss the specifics of these types of control elsewhere.

  • Label transcriptional control for the step between DNA and RNA, which controls when and how often a gene is transcribed.
  • Indicate that this is the only point where control ensures a cell will not synthesize unnecessary intermediates, thereby wasting resources, so for most genes, this type of control is very important.
  • We consider control at the level of chromatin packaging to be a type of transcriptional control, though some texts consider it to be a separate level of control.
  • Label RNA processing control for the step between RNA and mRNA.
    • This is where a cell controls the splicing and processing of RNA transcripts.
  • Label RNA transport and localization control for the step between mRNA in the nucleus and mRNA in the cytoplasm.
    • Selecting which mRNAs are exported to the cytoplasm and where they localize to is another way cells regulate their proteins.
  • Label translational control for the step between mRNA and protein.
    • Here, cells control which mRNAs get translated into protein.
  • In addition, indicate that mRNA is also controlled via mRNA degradation control.
    • Cells can destabilize specific mRNAs in the cytoplasm to limit protein production.
  • Draw a degraded mRNA to illustrate this concept.
  • Finally, label protein activity control for the step between protein and active protein as.
    • Cells can selectively activate, inactivate, localize or degrade proteins after they have been synthesized.

This concludes our overview of gene expression regulation.

UNIT CITATIONS:

  1. Campbell, N. A. & Reece, J. B. Biology, 7th ed. (Pearson Benjamin Cummings, 2005).
  1. Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K. & Walter, P. Molecular Biology of the Cell, 5th ed. (Garland Science, 2008).
  1. Alberts, B., Bray, D., Hopkin, K., Johnson, A., Lewis, J., Raff, M., Roberts, K. & Walter, P. Essential Cell Biology, 3rd ed. (Garland Science, 2010).
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  1. Perdew, G. H., Vanden Heuvel, J. P. & Peters, J. M. Regulation of Gene Expression: Molecular Mechanisms. (Humana Press, 2006).
  1. Hames, D. & Hooper, N. Instant Notes in Biochemistry. (Taylor & Francis, 2004).
  1. Krebs, J. E., Lewin, B., Goldstein, E. S. & Kilpatrick, S. T. Lewin's Essential Genes. (Jones & Bartlett Publishers, 2013).
  1. Snape, A., Papachristodoulou, D., Elliott, W. H. & Elliott, D. C. Biochemistry and Molecular Biology. (OUP Oxford, 2014).
  1. Lewin, B., Krebs, J., Kilpatrick, S. T. & Goldstein, E. S. Lewin's GENES X, Volume 10. (Jones & Bartlett Learning, 2011).
  1. Wood, B. J. B. & Warner, P. J. Genetics of Lactic Acid Bacteria. (Springer Science & Business Media, 2012).