Mrna Processing

Question 1

Guanine cap is formed to..

Answer 1

To prevent degradation of 5 prime end

Also site for recognition for ribosome to bind for translation to start

Question 2

What enzyme binds to initiate transkation

Answer 2

EIF4E

Question 3

Function of poly A tail

Answer 3

Facilitated mrna transport out of nucleus
Also prevents 3’ 5’ exonuclease activity
Facilities translation since ‘PAB’ is a component of translation machinery

Question 4

In addition of poly A tail, what happens

Answer 4

Cpsf binds downstream of AAUAAA region but upstream of GU rich region and ctsf binds there. Interact and bring more proteins that form an RNA cleavage complex. Cleave mrna at poly A signal. Incorporate PAP protein to add adenine residue. PAB determines if it is enough and signals PAP to stop and dissociate

Question 5

Functions of PAB II

Answer 5

Binds nascent poly A tail about 10 nt long
Provides processivity to pap
Controls length of poly a taio

Question 6

What are the 3 conserved elements of an intron

Answer 6

3’ Splice site
5’ splice site
Branch point

Question 7

SnRNPs

Answer 7

Small nuclear ribonucleoprotein particles

Question 8

U1, U2 and U3 base pair where?

Answer 8

U1 with 5 prime splice site
U2 with branch point
U4 recognizes 3

Question 9

Group 1 introns and group 2 introns self splicing difference

Answer 9

Group 1 no lariate

Group two lariate

Question 10

What are ribozymes and examples

Answer 10

Rna molecules capable of catalyzing a biochemical reaction. Example group 1 and 2 introns. RnaseP(5’ cleavage of trna) and ribosome(peptidyl transferase reaction)