Topic12.pdf - Topic 12 Eukaryotic Regulation 1 Characterize mechanisms of eukaryotic transcriptional regulation and compare these mechanisms to

Topic12.pdf - Topic 12 Eukaryotic Regulation 1 Characterize...

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Topic 12: Eukaryotic Regulation 1. Characterize mechanisms of eukaryotic transcriptional regulation and compare these mechanisms to prokaryotic transcriptional regulation. 2. Consider the use of transgenic organisms to study genetic regulation. 3. Explore epigenetic regulation, including the mechanisms of epigenetic regulation and how patterns of epigenetic modifications change over time. 4. Consider imprinted genes and contrast these with more common epigenetic regulation. 1
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Big Question: How are genes turned “on” and “off” in eukaryotic cells?
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How is eukaryotic regulation similar to prokaryotic? Both responding to signals originating inside and outside of the cell. Both are mechanisms to modulate expression (increase up or down). Both have cis- and trans- regulators But more types of regulators and new terms for each
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How does eukaryotic regulation differ from prokaryotic? 1. Eukaryotes don’t have operons. Usually each gene has its own promoter and thus regulation (sort of.) 2. Regulation is combinatorial. 3. Transcription and translation are isolated in the cell More opportunities for regulation 4. Chromatin organization affects expression. Physical and chemical modifications (epigenetics) 4
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Transcription Factors Recall, basal transcription factors binds to a core promoter upstream of transcription start site capable of minimal levels of transcription Specific transcription factors affect level of expression as regulatory proteins Can increase expression, activator, or decrease expression, repressor. Needs a DNA binding domain and activators need an activation domain. 5 DNA-binding Activation domain-interacts with basal factors or nucleososome modification factors TFIID TATAA
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Transcription Factors Transcription factors may increase or decrease expression by binding to a specific cis- element Activators or Repressors. While some transcription factors bind both the DNA and the basal transcription machinery, others need the assistance of a co-activator (or co-repressor). Regulatory promoter
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Repressors a transcription factor that suppresses transcription Instead of interacting with basal transcription machinery, works by different mechanisms: actively push away RNA polymerase compete with activators for binding to a DNA site "quenching" – binding to the activator itself to prevent its binding to DNA or activation e.g. REST silencer- Neuron-Restrictive Silencer Factor ( NRSF ) binds an DNA sequence found in genes turned off in non-neuronal cells 7
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