catalytic RNAs (lecture 7)

Question 1

diff group I and II

Answer 1

I: G nucleoAde (cofactor)
a[acks phosphodiester bond

II: A nucleotide
lariat structure

Question 2

self splicing in vitro

Answer 2

In vitro self splicing is very slow, in vivo proteins have accessory
funcAons

Question 3

catalytic RNA mainly?

Answer 3

snRNAs and proteins form snRNPs
(small nuclear ribonucleic particles) snoRNA (guide processing of other small RNAs)

-> splicing!

snRNAs position reactants and
provide catalyAc site for intron-exon
cleavage and exon-exon fusion

Question 4

similarity between splicesome and

group II self splicing

Answer 4

Pre-mRNA splicing mechanism of splicesome evolved from

group II self splicing

Question 5

RNAse P

Answer 5

endonuclease involved in
tRNA processing (5’ processing)

Question 6

viroid:

Answer 6

small plant pathogens consisAng of cytoplasmic ssRNA ( genetic tool (RNAi)

rolling circle

Question 7

ribosome

Answer 7

is a ribozyme
The ribosome is composed of two-thirds RNA and one-third protein

rRNAs catalyse polypetide synthesis!!

Question 8

Riboswitches:

Answer 8

short sequence of RNA that changes conformaAon upon binding of small molecule
(metabolite), conformaAonal change results in transcripAon terminaAon

Question 9

RNA editing

e.g.

Answer 9

changes in the ORF of mRNA by base-modificaAons (A->I) or nucleoAde inserAon

Trypanosoma: