Transcription and RNA Processing

Question 1

What substance found in mushrooms can inhibit the RNA pol II?

Answer 1

Alfa-amanitin

Question 2

RNA pol I synthezise almost all rRNA, except?

Answer 2

5S rRNA - RNA Pol III

Question 3

What does the prokaryotic RNA pol need to begin and stop transcription? What drug inhibit it?

Answer 3

• Single RNA pol (alfa2, beta-beta’) - sigma to initiate at a promoter; rho factor to finish
• Rifampin

Question 4

What is the shine-dalgarno sequence in prokaryotes?

Answer 4

Sequence where ribosomes bind at the 5’ UTR of mRNA to translate it (can occur simultaneously with transcription)

Question 5

What is the function of the 7-methylguanosine cap when added to 5’ end pre-mRNA?

Answer 5

Is a ribosome-binding site and helps to protect the mRNA for degradation

Question 6

What is the function of the poly-A tail attached to 3’ end of mRNA?

Answer 6

Protects against rapid degradation and aids in the mRNA transport to the cytoplasm

Question 7

What is the function of small nuclear RNA (snRNA)?

Answer 7

Participate in splicing (remove introns) of mRNA.

Is only in eukaryotic nucleus

Question 8

What toxins inactivate the 28S rRNA in the 60S subunit of the eukaryotic ribosome?

Answer 8

Shiga toxin (Shigella dysenteriae) and Verotoxin (shiga-like toxin, enterohemorrhagic E. coli)

*A subunits of toxins - RNA glycosylases: remove single adenine from 28S rRNA - prevents aminoacyl-tRNA binding to ribosome, halting protein synthesis.