Regulating Gene Expression from RNA to Protein

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Regulating Gene Expression from RNA to Protein
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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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A processed mRNA ready for translation
5 untranslatedregion
3 untranslatedregion
Protects from degradation
Protects from degradation/ transport
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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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Seeds germinated underground begin growing in
darkness then emerge into light and begin
photosynthesis
energy from seed
energy from sun
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The level of this mRNA increases after plants are
exposed to light.

• How might the cell accomplish this?

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The level of this mRNA increases after plants are
exposed to light.

• How might the cell accomplish this?Increased
  transcription and/or decreased mRNA degradation

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Northern blot analysis The level of this mRNA
increases after plants are exposed to light.

• How might the cell accomplish this?
• Does this necessarily lead to increased protein
  production?

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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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Fig 15.25
Regulation of iron assimilation in
mammals Regulating of Translation
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Fig 15.26
Ferritin is regulated at translation
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C. elegans is commonly used to study development
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C. elegans development
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C. elegans mutants with cells that do not develop
properly.
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C. elegans mutants with cells that do not develop
properly. The product of these genes was found
to be RNA?
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MicroRNAs (miRNA) are 22nt RNAs that play
important regulatory roles
Cell vol. 116, 281-297 2004
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miRNA expressed
How do microRNAs control gene expression?
miRNA processed to 22nt RNA
Mature miRNA
Fig 15.23 and
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A processed mRNA ready for translation microRNAs
inhibit translation by binding to the 3 end of
mRNA
microRNA bind to 3-UTR
5-UTR
3-UTR
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miRNA expressed
the 3 end with attached microRNA interacts with
the 5 end, blocking translation
miRNA processed to 22nt RNA
Mature miRNA
Fig 15.23 and
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miRNAs can lead to methylation of DNA that leads
to inhibition of transcription
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microRNAs primarily target gene products that
function during development
Tbl 1
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tissue specific expression of mouse microRNA
PNAS vol. 101 1 pg 360-365, 2004
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Silencing RNAs (siRNA) are artificially induced
dsRNA
Fig 15.21
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siRNA with exact matches to the target mRNA
causes degradation of the mRNA
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microRNA
siRNA
mRNA degraded
Translation inhibited
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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 16.1
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Phosphorylation and dephosphorylation of proteins
can change activity
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Ubiquitinization targets proteins for degradation
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All protein interactions in an organism compose
the interactome
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Some proteins function in the cytoplasm others
need to be transported to various organelles.
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How can proteins be delivered to their
appropriate destinations?
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Fig 13.23
Proteins are directed to their destinations via
signals in the amino acid sequence
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Protein Destinations secretion or membrane
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• Signal sequences target proteins for secretion

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Translation of secreted proteins
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Translation of membrane bound proteins
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Translation of secreted or membrane bound proteins
This step determines secretion or membrane bound.
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Protein Destinations nucleus
Signal anywhere in protein, Translation in
cytoplasm, Signal not removed
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Protein Destinations mitochondria or chloroplast
Signal translated first, Translation in
cytoplasm, Signal removed
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Protein Destinations signals in protein
determine destination
Tbl 13.8
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Development differentiating cells to become an
organism
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