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10 Cards in this Set
- Front
- Back
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RNA Components |
Phosphate Phosphodiester Link Bases - C, A, G, U Ribose - has OH group Synthesised 5’ to 3’ |
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Transcription by Pol 2 generates pre-mRNA |
Transcription occurs, also cap formation and poly (A) addition PRIMARY TRANSCRIPT (pre-mRNA) Undergoes splicing to give mature mRNA |
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Pre-mRNA Processed by Capping and Splicing |
5’ cap and 3’ polyA Tail of pre-mRNA are retained as it’s processed Capping allows cell to assess whether both ends are present before RNA is exported from nucleus for translation |
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When is 5’cap added? |
Added to emerging pre mRNA site specific phosphorylation of Pol 2 at C terminal recruits capping proteins Capping occurs when pre-mRNA is ~25 nucleotides long |
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What effects occur to the structure due to 5’ capping? |
Loss of phosphorylation group Formation of a rare 5’-5’ triphosphate linkage with GTP Methylation of terminal guanine Additional methylations |
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What does 5’ capping do? |
Provides Stability |
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When is 3’ Poly-A Tail added? |
As pre-mRNA is completed Site specific phosphorylation of Pol 2 at C terminal recruits 3’ end processing proteins E.g. poly-A polymerase |
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Where can you find 3’ Poly-A Tail? |
Can be 100’s of nucleotides beyond the 3’ end of mature mRNA (outwith the coding region) |
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What effect does Poly-a Tail have on mRNA? |
It may increase the stability of mRNA and enhance its translation |
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Splicing of pre-mRNA |
Site specific phospho |
