Lecture 22: RNA Processign II

Question 1

Branch Point

Answer 1

At the region where the S2 small nuclear RNA base pairs and the A residue stick out due to skipping

Question 2

Mutation in Intron that modifies nucleotide around splice site

Answer 2

Altering residue near 5’ end of intron stops the splicing

Question 3

Splicesome

Answer 3

Once U2 and U1 bound to its corresponding intron splice site and branch point , it recruits U4//6//5 and the brings both ends close to one another so size doesn’t matter. Then U1 and U4 kicked off so the complex ends can be close together

Question 4

Energy Expenditure During Splicing

Answer 4

Net 0

Question 5

Debranching enzyme

Answer 5

Breaks the bond at branch point and then it gets degraded rapidly

Question 6

Self Splicing Type 1

Answer 6

No splice some because secondary structure naturally brings them together and is common in plants

Question 7

Absence of GU…..AG

Answer 7

AU……..AC 1% human introns. require different snRNPs because they need to match the base bair with different snRNAs

Question 8

Trans-splicing

Answer 8

can do it on different molecule and no lariat forms just two introns (C. elegans)

Question 9

Ribosomal rRNA synthesis (pol ?)

Answer 9

Pol I
In the nucleolus

Question 10

Ribosomal RNA Processing

Answer 10

Pre-rRNAs are modified:
- Ribose methylation and conversion of U to pseudouridine
- Modification sites are determined by base pairing with snoRNAs that associate with modifying enzymes in RNPs

Question 11

snoRNAs

Answer 11

Form a weird double hairpin with some single stranded ran in the middle so that it can be bound

Question 12

tRNA pol?

Answer 12

Polym III

Question 13

tRNA processing

Answer 13

Cleave sequence on 5’
CCA added to 3’
Extensive modification of internal base

Question 14

Exonic Splicing Enhancers

Answer 14

SR proteins which bind to sites in exon interact with U1 because they interact with one another telling the U1 this is a site

Question 15

3’ intron identification

Answer 15

U2AF65 and 35 bind to the U2 to tell them where the site is to cleave

Question 16

ALternative splicing

Answer 16

Increase the coding capacity of the genome by producing multiple protein mRNAs from the same pre-mRNA