RNA Metabolism

Question 1

What is the cap and where is added?
Why is it important?

Answer 1

7-Methyl-Guanosine added at the 5´end the transcript,

It is a marker, important for translation

Question 2

How is the cap attached?

Answer 2

By enzymes on the C-terminal domain of RNA Pol II, during transcription

Question 3

Where is the poly-A tail attached?

How many AAs?

Answer 3

at 3´end, next to AAUAAA sequence recognized by polyadenylate polymerase - doesn’t need a template !!!

20 -250

Question 4

The sequence of poly adenylation:

Answer 4

Binds on AAUAAA sequence –> cuts near site -»> Poly A Polymerase adds AAs

Question 5

What helps in the process of splicing?

Answer 5

small nuclear ribonuclear proteins (snRNPs, U1, U2)
they bind at the exon and intron junction to facilitate splicing

Question 6

What are microRNAs?

Answer 6

-short highly conserved noncoding RNA sequences
-bind at 3´end of a complementary mRNA -> to repress its translation
-translational repression or gene silencing