1 / 17

GENE REGULATION

GENE REGULATION. Definition. The mechanisms that determine the types of cells in which a gene will be transcribed. When the mRNA will be exported to the cytoplasm. When and how often the mRNA will be translated, and the duration of time before the mRNA is degraded. Regulation categories.

jetta
Download Presentation

GENE REGULATION

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. GENE REGULATION

  2. Definition • The mechanisms that determine the types of cells in which a gene will be transcribed. • When the mRNA will be exported to the cytoplasm. • When and how often the mRNA will be translated, • and the duration of time before the mRNA is degraded.

  3. Regulation categories • Negative regulation • Positive regulation • Negative regulation is more common in prokaryotes, positive regulation in eukaryotes.

  4. Negative regulation • Means that the default state of transcription is (ON) unless a repressor turns it (OFF).

  5. Repressible transcription • Repressible transcription needs a co-repressor to bind with the aporepressor to make an active repressor. Transcription wont occur.

  6. Inducible transcription • Inducible transcription needs an inducer to bind with the repressor and inactivate it, so the repressor loses its capability to bind DNA. Transcription will occur.

  7. Positive regulation • Means that the default state of transcription is (OFF), unless a protein turns transcription ON, which is called transcriptional activator protein. It binds the activator binding site on DNA.

  8. Autoregulation • Means that the protein product of a gene regulates its own transcription. • Most genes include positive and negative regulatory elements.

  9. Constitutive synthesis • Transcription and translation of a gene takes place at a constant rate independent of the presence or absence of any inducer or repressor molecules.

  10. Operator • It is a regulatory region (or binding site) in DNA for the repressor protein to control gene transcription.

  11. Operon • A collection of genes regulated by an operator and repressor.

  12. Promoter • A DNA sequence at which RNA polymerase binds and initiate transcription. • RNA polymerase is an enzyme responsible for transcription of DNA to RNA.

  13. TATA box • The base sequence 5’-TATA-3’ in the DNA of a promoter. • TATA-box-binding protein: A protein that binds to the TATA motif in the promoter region of a gene.

  14. Not only ON-OFF systemEx:(Tryptophan biosynthesis) • trpR gene produces trp aporepressor (regulatory protein) . It does not bind to the operator unless it is first bound to tryptophan. That means botn form trp repressor. • Insufficient tryptophan means that aporepressor wont bind trp operator and transcription occurs. • Trytophan acts as co-repressor.

  15. Transcriptional activator proteins • Helix-turn-helix motif • DNA-binding motif.

  16. Enhancers • Enhancers are found at a variety of locations around the gene they regulate. • Short (less than 20 base pairs)

  17. Silencers • Short sequences of DNA. • They promote the assembly of large protein complexes that prevent transcription.

More Related