Eukaryotic gene control
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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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Eukaryotic gene control

Eukaryotic Gene control

No OPERONS!!!!


Some key points

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


Eukaryotic genome structure

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


Genome structure cont

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


Typical structure of eukaryotic genes no operons

Typical Structure of Eukaryotic GenesNO OPERONS!!!


Transcriptional control

Transcriptional control

Chromatin Structure

  • DNA folding/unfolding

    • Heterochromatin(inactive)

    • Euchromatin (active)


Transcriptional control1

Transcriptional control

  • Histone modification

    • Attachment of acetyl groups (COCH3) to histone tails loosens their hold(active)

    • Methylation of tails(inactive)


Transcriptional control cont

Transcriptional Control cont….

  • DNA methylation of specific bases(inhibitory)

    • Usually long term

    • Methylases

    • Demethylases?

    • X-inactivation

    • Development

      • Patterns passed on to daughter cells


Even more transcriptional control

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


Eukaryotic gene control

Cont…

  • Transcription factors (PROTEINS)

    • Activators vs repressors

    • Bind to enhancers

    • 100s

    • Gene Expression/specialization may be due to unique combo of available transcription factors


Post transcriptional control

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


Plus all the stuff that prokaryotes do

Plus, all the stuff that prokaryotes do!!!

  • Translational control

    • Initiation complex

  • Post translational control

    • Protein modification

    • Protein degradation

    • Protein targeting


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