Splicing & Processing of RNA Flashcards
RNA poly 1 transcribes what genes?
5.8S, 18S, & 28S rRNA genes
What are 2 examples consistency sequences?
- transactivators
- invariant A
What is RNA poly 2 transcribes what genes?
- all protein-coding genes
- snoRNA
- miRNA
- siRNA
- snRNA
What are the 3 steps for mRNA processing?
- Capping (5’ end)
- Splicing (notice this is mRNA not rRNA)
- Poly-A addition (3’ end)
When does the methyl during 5’ capping get added to?
after synthesis of guanine (7-methylguanine)
What happens if there is no 5’ cap?
CANNOT get mRNA to the ribosome
What gene leads to deafness?
TECTA
What is the human genome browser an example of?
If there are 2 splicing alternative, there will be 2 different primary transcripts that will have different exons.
What invariant is important for splicing?
invariant A ( important for consistent sequence)
What do introns turn into during mRNA splicing?
lariat structure
What is the process of mRNA splicing?
- Takes advantage of the 2OH on the invariant A nucleotide to attack the phosphodiester bond @ the 5’ end of an intron
- The open OH on the exon closer to the 5’ end breaks phosphodiester bond between the 3’ end of intron and the exon
- 5’ end of intron forms bond with 2’ OH of invariant A
What are snRNPs made of?
polypeptides & RNA
What are spliceosomes?
set of proteins important for making the lariat happen
What are hnRNPs?
proteins that block formation of spiceosome & proteins that contact spliceosome
In the case of igM, what are produced?
either secreted or membrane bound versions are produced depending on alternative splicing
What helps to stimulate the formation of the spliceosome?
SE proteins
What are the 4 RNA seqeunces?
- ESE (Exon Sequence Enhancer)
- ESS (Exon Sequence Silencers)
- ISE (Intron Sequence Enhancer)
- ISS (Intron Sequence Silencer)
What can define what is an exon and what is an intron?
mutations & other things
What is the regulatory sequence in a poly-A tail?
AAUAAA
In what type of manner is a poly-A tail added?
template independent manner on 3’ end
What is a Cleavage and polyadenylation specific factor (CPSF)?
- attaches to the RNA polymerase II
- binds to the Poly-A signal site of the emerging mRNA
- recruits polyA polymerase.
When is RNA rapidly degraded?
if poly-A tails ARE NOT added
What are snoRNAs?
- aka guide RNAs
- small nucleolar RNAs
- direct the position of the base modification for rRNAs
What are the roles of the nucleolus, small nucleolar RNA, & small nuclear RNA?
- nucleolus: builds up ribosomes
- small nucleolar RNA: rRNA modifying enzyme
- small nuclear: RNA modifying enzymes
