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13 Cards in this Set
- Front
- Back
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What are the 4 mechanisms to regulate gene expression?
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1. binding of transcription factors to promotor and enhancer sequences in the gene
2. splicing, stability and translation of the mRNA (post-transcriptional) 3. posttranscriptional modifications of the protein 4. epigenetic regulation by modification of chromatin and methylation of DNA |
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Transcription factors work only in cis. what does this mean?
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they must be on the same chromosome as the gene they are regulating
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why is RNA regualtion important during early development?
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transcription is largely absent during early stages so post-transcriptional control is a key means of regulating gene expression.
Degradation will remove gene products that may interfere with later developmental stages. Selected translation can turn on necessary gene products required for development to proceed |
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why is transcription likely skipped during early development?
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cell division is fast - no time
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what is RNA splicing?
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mechanism of generating different protein variants from the same gene. splices together different exons and leaves out introns
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what tells the cell how to splice the RNA together?
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signal sequences in the DNA
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what are the 4 main splice signals?
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5' splice site
3' splice site branch site polypyrimidine tract |
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what are the 4 main types of alternative splicing?
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exon skipping
alternative acceptor site alternative donor site intron retention |
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what is the stability of mRNA often dependent on?
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length of the poly A tail which is often dependent on 3' untranslated sequences which often contains sequences that bond to protein complexes that can affect stability.
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give 3 translational control mechanisms.
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1. absence of 5'cap or lack of poly A tail - added when proteins are required
2. joining the 5' and 3' end together with maskin which prevents the binding of crucial translation initiation factors 3. binding of inhibitory proteins that block translation |
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what are 4 possible things that a protein might need to undego to become activated?
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1. cleavage - eg insulin
2. assemble into a complex eg haemoglobin or ribosomes 3. bind to ions eg metalloproteases 4. covalently modified by attachment of phosphate or acetate groups |
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what is epigenetic regulation?
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heritable and reversible cellular or organismal traits that do not involve changes to the underlying sequence
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what are 3 examples of epigenetic moduification?
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1. X chromosome inactivation
2. histone modification 3. DNA methylation |
