Lecture 6: RNA Processing Flashcards
1
Q
overview of RNA Processing
A
- RNA is synthesized from DNA templates but the molecules are often not functional
- these are pre-RNA and need to be modified to become mature
2
Q
benefits of RNA processing
A
- regulation of gene activity
- diversity (via alternative splicing)
- quality control
3
Q
RNPs in Processing
A
- protein and RNA template
- RNA can be catalytic (ribozymes)
- some RNPs contain guide RNA that base pair with pre-RNA and guide RNP to right place
4
Q
tRNA and rRNA Processing
A
- made as long precursors that must be processed
- encoding several RNAs in one precursor ensures that similar amounts of each RNA are made
5
Q
ribonucleases
A
cleave the RNAs into smaller parts
6
Q
exonucleases
A
- successively remove nucleotides from the end of a transcript usually in 3’-5’ direction
- not sequence specific
7
Q
endonucleases
A
- cleave the DNA within the strand
- some specific for double-stranded RNA or single stranded
examples: RNase III, RNase P, restriction enzymes
8
Q
RNase III
A
- excises bacterial rRNAs
- recognizes double-stranded RNA
9
Q
RNase P
A
- 5’ trimming of tRNAs
bacteria: RNA component can cut RNA, protein part enhances activity
eukaryotic: RNA component can’t cut RNA alone but is essential
10
Q
self-splicing
A
some rRNA introns can catalyze their own removal
- precursor RNAs therefore act as ribozymes
11
Q
CCA sequence
A
- conserved 3’ end of tRNAs
- attachment site for the amino acid
- added to tRNA by a CCA adding enzyme
