Chapter 6: 6.5 RNA Maturation in Eukaryotes

Question 1

After transcription of eukaryotic pre-mRNA, what modifications occur before translation?

Answer 1

1. 5’ capping
2. Polyadenylation
3. Splicing

Question 2

What is 5’ capping? What is its purpose?

Answer 2

A modification to the 5’ end of the pre-mRNA, which consists of a methylated guanosine (7-methylguanosine)
* Allows for efficient translation and prolongs the stability of the mRNA

Question 3

What is polyadenylation? What is its purpose?

Answer 3

A modification to the 3’ end of the pre-mRNA, which consists of several hundred “A” nucleotides to give a poly-A tail
* Prevents RNA degradation and helps export pre-mRNA to cytoplasm

Question 4

Eukaryotic genes contains ——- and —–

Answer 4

• Introns
• Exons

Question 5

True or False:

Exons are spliced and the introns are joined together

Answer 5

False, exons are joined together after introns are spliced

Question 6

After 5’ capping, Polyadenylation, and Splicing, what does pre-mRNA become?

Answer 6

mRNA

Question 7

Where does splicing occur? What does splicing?

Answer 7

• Occurs in the nucleus
• Conducted by proteins called spliceosomes

Question 8

Why does splicing have to be a precise process?

Answer 8

Leaving nucleotides in can cause frameshift mutations that generate nonfunctional proteins