Chapter 14.4.1 (Exam 3) Processing

Question 1

What is the gene structure of eukaryotes?

Answer 1

Genes are made up of introns and extrons

Question 2

What are introns?

Answer 2

The noncoding regions that get transcribed, but then sliced out of pre-mRNA in the nucleus

Question 3

What are extrons?

Answer 3

The coding sequences that reach the ribosome

Question 4

What is included in pre-mRNA processing?

Answer 4

RNA splicing

Addition of G-Cap on the 5’ end

Addition of poly-A tail on the 3’ end

Question 5

Describe the G-Cap that is added to the 5’ end during pre-mRNA processing.

Answer 5

5′ cap - added at the 5′ end; a modified GTP

Function:
Facilitates binding to a ribosome

Protects mRNA from being digested by ribonucleases

Question 6

Describe the poly-A tail that is added to the 3’ end during pre-mRNA processing.

Answer 6

poly A tail - added at 3′ end; 100-300 adenines

Function:
Assists in export from the nucleus

Important for stability of the mRNA

Question 7

What is the role of RNA splciing?

Answer 7

RNA splicing removes introns and splices exons together

Question 8

How does the cell know where to splice out the introns in the pre-mRNA?

Answer 8

Specific sequences commonly found in introns (consensus sequences) allow the splicing machinery to identify and remove introns

Question 9

What would happen if there was a mutation in the consensus sequence?

Answer 9

Introns would not be removed and would be expressed