Term
| Relationship of hnRNA to mRNA |
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Definition
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Term
| 4 major processing steps most affecting Eukaryotic mRNAs |
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Definition
-5' end capping
-3' end polyadenylation
-Intron Splicing
-Cap and Internal Nucleotide Methylation
-Correct capping, polyadenylation, and splicing are required for mRNA to be exported from the nucleus |
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Term
| Differences between Prokaryotic and Eukaryotic mRNA 5' and 3' ends |
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Definition
Eukaryotic
-5' cap is modified Guanine Nucleotide
-3' is poly(A) tail (~250)
Prokaryotic
-5' is triphosphate
-3' is also polyadenylated, but much shorter (~15-60) |
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Term
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Definition
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Term
Intron Splicing
What are the chemical steps?
What are the absolute requirements?
What is the major (unusual) feature of this process?
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Definition
-Intron splicing is precise removal of intron sequences from primar hnRNA transcript
-Chemical steps are transesterifications
-Requires snRNPs, "GU" at 5' end/"AG" at 3' end, and "A" at lariat attachment point
-Formation of intron lariat, and unusual 5'-2' bond |
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Term
mRNA polyadenylation
What are the 3 steps?
What are the requirements? |
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Definition
1. Recognition of correct polyadenylation site
2. Cleavage of pre-mRNA at correct site, leaving 3' hydroxyl group
3. Addition of ~250 adenosine residues
Requires upstream sequence element "AAUAAA" w/in 12-35 nucleotides of cleavage site ("polyadenylation signal")
Requires downstream sequence element "U-rich" or "GU-rich" sequence ~10-24nt downstream of cleavage site
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Term
| Changes in splicing lead to changes in the protein encoded by an mRNA |
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Definition
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Term
| Changes in polyadenylation can lead to changes in the protein encoded by an mRNA |
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Definition
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