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18 Cards in this Set
- Front
- Back
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RNA pol I makes?
RNA pol III makes? RNA pol II makes? |
rRNA
tRNA, 5snRNA heteronuclear RNA (hnRNA)-->mRNA |
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Which of the RNA pol are in the nucleolus? Nucleoplasm
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Nucleolus: RNA pol I
Nucleoplasm: RNA pol II & III |
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RNA pol III has internal promoter sequence
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5s RNA has 1 promotor
tRNA has 2 promotor snRNA has promoters upstream from t/sc start |
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Enzyme of RNA pol III
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-3 accessory factors: TFIII-A, B, & C
-TFIII-A & C are bound on non-template strand & stay-on. |
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What processing occurs to RNA pol III
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1. 5', 3' ends trimmed
2. pCpCpA added to 3' 3. Dihydroxy-U 4. PseudoU 5. Methylation |
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Enzyme of RNA pol II
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TFII-D binds to TATA box & recruits t/sc initiation complex
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Processing of hnRNA to mRNA
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1. Capping of 5' end
2. Polyadenylation of 3' end |
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Capping of 5' end of mRNA
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1. GTP added to 5'--5' linkage
2. Guanine base is methylated to 7-methyl-G 3. Ribose methylated at position 1 or 2 |
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Polyadenylation of 3' end
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-Poly A gives stability (from degredation)
-Poly A adds 100 nts of A's which signals to cut downstream -Poly A good tag for biologists by using dT linked to a magnetic bead -Histone mRNA not polyadenylated bc no need for stability |
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What does "mRNA is multi-partite" mean?
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Coding regions are interrupted by non-coding regions
Introns: non-coding regions Exons: coding sequences These are located on hnRNA |
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Splicesome
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-snRNA recognize splice site
-5 types 1. U1-binds to the 5' splice site 2. U5-binds to the 3' splice site |
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Histone vs. B-globin stabilities
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1. Histone mRNA not stable bc only appears during S-phase
2. B-globin stable |
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RNA silencing via siRNA and miRNA
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siRNA: dsRNA cut into small pieces by dicer
miRNA: hairloop RNA-->dsRNA-->cut by dicer into 21-22 nts. |
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Post-transcriptinal/gene silencing
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siRNA binds to mRNA--> RISC holds siRNA in place-->blocks ribosome t/sl of mRNA
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mRNA degradation
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siRNA binds to mRNA
RISC holds siRNA in place marked for cleavage by nuclease |
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Self-splicing RNA's (ribozymes)
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rRNA from tetrahymena can do its own splicing, both endonuclease cleavage & ligation
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tRNA processing: ribonuclease P from Ecoli
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cuts precursor molecule to form correct 5' ends of tRNA
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the rRNA that is the catalyst for formation of peptide bonds
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Ribosome
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