Transcription and mRNA processing

Question 1

Template strand is

Answer 1

3’ ——> 5’

Question 2

Upstream and Downstream directions

Answer 2

Up- 3’ direction

Down -5’ direction

Question 3

Provides DNA sequence specificity

Answer 3

Sigma factor

Question 4

RNA poly 1

Answer 4

rRNA genes (5.8, 18, and 28 S rRNA genes)

Question 5

RNA poly 2

Answer 5

all coding (mRNA) genes. snoRNA, miRNA, siRNA, snRNA

Question 6

RNA poly 3

Answer 6

tRNA and 5S rRNA genes

Question 7

Why are nucleoli larger in cancer cells?

Answer 7

Higher rate of proliferation means it needs more ribosomes.

Question 8

The different polymerases have different

Answer 8

TF

Question 9

Bacterial mRNA lack

Answer 9

5’ -cap

Question 10

When are primary (pre-mRNAs) are capped?

Answer 10

As soon as they are transcribed by RNA polymerase II

Catalyzed by guanylyl transferase using GTP as a substrate.

Capped G residue is methylated at the N-7 position.

Question 11

Why do cells need to cap their mRNA?

Answer 11

Recognition

Cap distinguishes RNA molecules from other mRNA molecules (RNA poly 1 and 3 don’t use the cap).

mRNAs need a cap to be exported from the nucleus.

cap is necessary for translation.

cap stabilizes mRNA in the cytoplasm

Question 12

Termination of transcription occurs only after RNA polymerase has ?

Answer 12

transcribed a consensus AAUAAA

the poly A tail stimulates translation and governs the stability of mRNA.