Eukaryotic Gene control
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Transcript of Eukaryotic Gene control
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Eukaryotic Gene control
No OPERONS!!!!
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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 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
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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
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Typical Structure of Eukaryotic GenesNO OPERONS!!!
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Transcriptional controlChromatin Structure DNA folding/unfolding
Heterochromatin(inactive)
Euchromatin (active)
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Transcriptional control
Histone modification Attachment of
acetyl groups (COCH3) to histone tails loosens their hold(active)
Methylation of tails(inactive)
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Transcriptional Control cont….
DNA methylation of specific bases(inhibitory) Usually long
term Methylases Demethylases? X-inactivation Development
Patterns passed on to daughter cells
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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
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Cont… Transcription
factors (PROTEINS) Activators vs
repressors Bind to enhancers 100s Gene
Expression/specialization may be due to unique combo of available transcription factors
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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
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Plus, all the stuff that prokaryotes do!!!
Translational control Initiation complex
Post translational control Protein modification Protein degradation Protein targeting