1 / 24

Chapter 19

Chapter 19. Organization and Regulation of the Eukaryotic Genome. Eukaryotic gene expression. Much more complex than prokaryotic Larger number of interacting proteins Placement of transcription/translation lends itself to more opportunities for regulation. More DNA

tearly
Download Presentation

Chapter 19

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. Chapter 19 Organization and Regulation of the Eukaryotic Genome

  2. Eukaryotic gene expression • Much more complex than prokaryotic • Larger number of interacting proteins • Placement of transcription/translation lends itself to more opportunities for regulation. • More DNA • Flexible control needed for complex programs and multiple tissue types.

  3. Transcription Factors General – • Groups of proteins necessary for recruitment of RNA polymerase and transcription apparatus • Do not increase rate of transcription

  4. Specific – • Tissue or time dependent manner to stimulate higher levels of transcription above the base rate • Referred to as activators • Contain a DNA binding domain and a separate acting domain that interacts with the transcription apparatus.

  5. Promoters • Form binding sites for general transcrption factors • Mediate the binding of RNA polymerase

  6. Enhancers • Contain binding sites for specific transcription factors • Act over long distances by triggering DNA to bend forming loops • This positions the enhancer closer to the promoter.

  7. Chromosome structure • Composed of a DNA-protein complex called chromatin. • Euchromatin/heterochromatin • During preparation for mitosis, the chromatin becomes condensed down into linear chromosomes = “packing”

  8. Chromatin packing • Histones are proteins responsible for the 1st level of chromatin packing. • DNA becomes wound around this histone core to form  nucleosome (“bead”)

  9. Eukaryotic regulation Accomplished through – • DNA structure modification • Transcriptional level • Post-transcription level

  10. Gene Regulation via Structure • Most cells within an organism contain the same set of genetic instructions, but the differential expression of specific genes determines the specialization of the cells. 3 ways to regulate via structure: • Histone modification • DNA methylation

  11. Regulation at the Transcription level • Regulating gene expression at the transcription level is the most important and universally used stage. • transcription factors, associated with most eukaryotic genes, help regulate transcription by binding certain proteins. • This process aids in the precise regulation of gene expression.

  12. numerous in eukaryotes • necessary for assembly of the “transcription initiation complex” • necessary for recruitment of RNA polymerase to bind to promoter • necessary for initiation of transcription (but do not increase the base rate of transcription)

  13. Post transcriptional miRNA (microRNA’s) • arise from a small, single stranded RNA encoded genes in the nucleus. • formed from a precursor molecule, diced into fragments and associated with a protein complex. • binds to a complementary mRNA sequence and either degrades the target or blocks translation.

  14. small interfering RNA (siRNA’s) • similar to miRNA’s but arise form a long, double stranded RNA • can come from either the cell or outside of the cell.

More Related