Regulating Eukaryotic Gene Expression

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Regulating Eukaryotic Gene Expression
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Fig 15.1

• Why change gene expression?
• Different cells need different components
• Responding to the environment
• Replacement of damaged/worn-out parts

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• Two points to keep in mind
• Cellular components are constantly turned-over.
• Gene expression takes time
• Typically more than an hour from DNA to protein.
  Most rapidly 15 minutes.

Fig 15.1
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• Gene expression can be controlled at many points
  between DNA and making the final proteins.
• Changes in the various steps of gene expression
  control when and how much of a product are
  produced.

Fig 15.1
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• Gene Expression is controlled at all of these
  steps
• DNA packaging
• Transcription
• RNA processing and transport
• RNA degradation
• Translation
• Post-translational

Fig 15.1
Fig 16.1
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• Gene Expression is controlled at all of these
  steps
• DNA packaging
• Transcription
• RNA processing and transport
• RNA degradation
• Translation
• Post-translational

Fig 15.1
Fig 16.1
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Tightly packaged DNA is unavailable. DNA
packaging changes as the need for different genes
changes.
Fig 10.21
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Fig 10.21
Different levels of DNA packaging
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Histones can be post-translationally modified,
which affects their abililty to bind DNA.
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Fig 12.15
Acetylation (-COCH3) post-translational
modifications of the histones loosen DNA binding
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Acetylation of histones (-COCH3) causes a
loosening of the DNA/histone bondunpackaging the
DNA.
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Fig 15.13
DNA methylation
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DNA methylation often inhibits transcription
Fig 15.14
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Fig 15.15
Epigeneticsthe inheritance of DNA
modifications, including methylaton
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• Gene Expression is controlled at all of these
  steps
• DNA packaging
• Transcription
• RNA processing and transport
• RNA degradation
• Translation
• Post-translational

Fig 15.1
Fig 16.1
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Eukaryotic transcription must be activated by
binding of transcription factors
Fig 12.14
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Mutations in the promoter show critical
nucleotides
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Fig 15.12
Enhancers are regulatory regions located some
distance away from the promoter
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Proteins that help bend DNA can play an important
role in transcription
Fig 15.12
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Fig 15.12
DNA bends to bring different areas in to close
contact.
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How do eukaryotic cells jointly express several
proteins (without operons)?
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Promoter sequences where transcription factors
can bind activating multiple gene in response to
the environment
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Fig 12.13
Promoters typically have several regulatory
sequences
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Steroid response element
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Fig 15.6

• Steroids bind to receptors/transcription factors
  inside cell
• get translocated to the nucleus
• bind to promoters andactivate transcription.

cytoplasm
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• Gene Expression is controlled at all of these
  steps
• DNA packaging
• Transcription
• RNA processing and transport
• RNA degradation
• Translation
• Post-translational

Fig 15.1
Fig 16.1