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Eukaryotic Gene control

Eukaryotic Gene control. No OPERONS!!!!. Some Key Points…. Gene control in eukaryotes is important for development into a multicellular organism Changing environmental conditions not as important (why?) Eukaryotes show gene control at all levels, and all seem to be equally important.

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Eukaryotic Gene control

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  1. Eukaryotic Gene control No OPERONS!!!!

  2. Some Key Points….. • Gene control in eukaryotes is important for development into a multicellular organism • Changing environmental conditions not as important (why?) • Eukaryotes show gene control at all levels, and all seem to be equally important

  3. Eukaryotic Genome Structure • Linear DNA, folded into several chromosomes (approx. 200,000,000 bps) • Histone proteins (tails) • 97% of DNA DOES NOT code for proteins • Tandemly repetitive (satellite) DNA • Telomeres & centromeres

  4. Genome Structure cont….. • Multi gene families • Genes that code for proteins w/ similar functions • May not all be near each other • May be controlled by the same regulatory elements • Gene amplification • Multiple copies of a gene • Temporary? • Selective gene loss • Insect metamorphosis • Gene rearrangements • B cell antibodies • T cell antigen receptors

  5. Typical Structure of Eukaryotic GenesNO OPERONS!!!

  6. Transcriptional control Chromatin Structure • DNA folding/unfolding • Heterochromatin(inactive) • Euchromatin (active)

  7. Transcriptional control • Histone modification • Attachment of acetyl groups (COCH3) to histone tails loosens their hold(active) • Methylation of tails(inactive)

  8. Transcriptional Control cont…. • DNA methylation of specific bases(inhibitory) • Usually long term • Methylases • Demethylases? • X-inactivation • Development • Patterns passed on to daughter cells

  9. Even more transcriptional control….. • enhancers • Sequences of bases • Same sequences used over & over • Distal vs proximal • One enhancer sequence may affect several related genes • Silencer sequences

  10. Cont… • Transcription factors (PROTEINS) • Activators vs repressors • Bind to enhancers • 100s • Gene Expression/specialization may be due to unique combo of available transcription factors

  11. Post-transcriptional control • mRNA editing • Alternative splicing • Transport (or not) to cytoplasm • 5’ cap • mRNA degradation-life span of mRNA • Poly A tail impt. • RNAi ? (Dicer) DICER

  12. Plus, all the stuff that prokaryotes do!!! • Translational control • Initiation complex • Post translational control • Protein modification • Protein degradation • Protein targeting

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