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13 Cards in this Set
- Front
- Back
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Levels of regulation of gene expression
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transcription initiation
transcription elongation translation post-translation |
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Objective of regulation of transcription initiation (aka mRNA synthesis, transriptional regulation)
Pros and cons? |
produce appropriate mRNAs that encode enzymes in response to changes in the environment.
Slower than direct regulation of enzyme activity, but more efficient (controls amount of the enzyme produced, "end product inhibition") |
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What determines whether transcription of genes is induced or repressed?
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presence or absence of substrate in environment
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Genes repressed subject to
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Negative control
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Genes induced subject to
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positive control
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What mediates positive and negative control?
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regulatory proteins
Repressors block, and activators enhance the activity or RNA polymerase |
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2 states of regulatory proteins and why would they be in one state or another?
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Active and inactive
presence or absence of inducing or repressing molecules |
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Inducible genes are generally involved in
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catabolism
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inducible genes are not expressed in
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absence of inducer
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2 ways to regulate inducible genes
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1. Active repressor + inducer=inactive repressor
2. inactive activator + inducer = active activator |
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Repressible genes are not expressed in the presence of
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repressing substrate (usually end product of biosynthetic pathway
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Repressible genes are generally involved in
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anabolism
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2 ways to regulate repressible genes
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1. Inactive repressor + end product = active repressor
2. Active activator + end product = inactive activator |
