RNA Processing and Gene Splicing

Question 1

How is prokaryotic and eukaryotic RNA processing different?

Answer 1

Prokaryotic mRNA is uses immediately and is not processed

Question 2

What enzyme attaches the 5’ cap and what kind of unique bond does it create?

Answer 2

Guanalyl transferase creates a 5’-5’ triphosphate bond

Question 3

What enzyme attaches the poly A tail?

Answer 3

poly(A) polymerase

Question 4

What is the sequence of the polyadenylation signal?

Answer 4

AAUAA

Question 5

What is a SnRNP?

Answer 5

Small nuclear ribonucleoprotein particles consist of a mall nuclear RNA and several associated proteins

Question 6

How are intron sequences recognized?

Answer 6

All introns begin with the sequence GU and end with the sequence AG, and include a branch site A surrounded by pyrimidines in the middle

Question 7

What protein binds to the poly A tail and what is its function

Answer 7

Poly(A) binding protein promotes export from the nucleus and translation, and inhibits degradation

Question 8

What is the role of U1?

Answer 8

Binds the 5’ splice site

Question 9

What is the role of U2?

Answer 9

Binds the branch site and forms part of the catalytic site

Like Bono, it’s at the center of attention

Question 10

What i the role of U5?

Answer 10

Binds the 3’ splice site and loops over to the 5’ site

Question 11

What is the role of U4?

Answer 11

Masks catalytic activity of U6

Question 12

What is the role of U6?

Answer 12

Catalyzes splicing

Question 13

How do U1, 2, and 5 bind to the mRNA?

Answer 13

They contain small RNA sequences that are complimentary to these sections

Question 14

Which two snRNP’s complex to catalyze the splicing process?

Answer 14

U2/U6

Question 15

What type of unique bond is characteristic of intron splicing?

Answer 15

During splicing, a 2’-5’ phosphodiester bond is created when the 2’ hydroxyl of the branch point attacks the 5’ splice site of exon 1, resulting in a spliced intron in a lariat formation

Question 16

Briefly, what is alternative splicing?

Answer 16

A process during gene expression that results in a single gene coding for multiple proteins by splicing different regions of the transcript. eg. processing that results in membrane bound vs. soluble fibronectin

Question 17

What is SR protein and what is its role?

Answer 17

Serine/arginine protein–promotes splicing by binding to exon/intron splicing enhancer regions

Question 18

What is hnRNP and what is its role?

Answer 18

Heterogenous nuclear ribonucleoprotein–inhibits splicing by binding to exon/intron splicing silencer regions