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15 Cards in this Set
- Front
- Back
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what are the 5 reasons eukaryotic gene regulation is more complex than prokaryotic gene expression
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-histones (more DNA)
-splicing, capping, polyadenylation -movement of mRNA into cytoplasm -mRNA stability -modulation of mRNA during translation |
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three types of cis-acting sequences in eukarytoes
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promotor (TATA box)
enhancer (increase transcription rates) silencer (represses transcription initiation) |
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what organism is the GAL system
in -what molecule is regulated -what type of system |
yeast
galactose inducible (presence of galactose, low glucose increases transcription of GAL system) |
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what two types of genes are produced by GAL system
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structural (transport galactose into cell)
regulatory |
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in GAL system, what occurs in absence of galactose
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Gal80p binds to Gal4p, covering Gal4p's trans-activation site
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in GAL system, what occurs in presence of galactose
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galactose binds to Gal3p, causing it to undergo a conformational change, allowing it to bind to Gal80p/Gal4p complex, exposing Gal4p trans-activation domain allowing it to become active
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what is Gal4p's role in GAL system
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it is a trans-activation domain that recruits RNA polymerase to transcribe the structural GAL genes
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what is non-sense mediated decay
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when splicing occurs, EJC are left to show cell where splicing occurred. If EJC occurs after a stop codon, the cell knows an error occurred and degrades the mRNA
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what is the mechanism of RNAi
-key player |
1. dsRNA introduced
2. Dicer cuts up dsRNA into siRNA 3. siRNA associate with RISC 4. RISC searches for complementary target sequences, and siRNA cleaves them so they degrade in the cytoplasm -siRNA is the key (and dsRNA) |
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how does RNAi regulate gene expression
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inhibits gene expression at level of translation
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what is the siRNA
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contain complementary sequences to the target mRNA, and when recognized, they cleave the targets
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how does miRNA work
-what type of regulation on RNA |
binds 3'UTRs and accelerates deadenylation and decapping
-post-transcriptional regulation |
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what 3 processes does miRNA regulate
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biological processes (metabolic)
development morphogenesis |
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what is significant about how miRNA binds to its targets
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imperfect complementarity to target
-can bind to multiple mRNAs, making it difficult to identify its targets |
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main difference between siRNA and miRNA
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siRNA: binds perfectly; works at level of translation to inhibit
miRNA: binds imperfectly; works at post-transcriptional level; multiple targets |
