PROKARYOTIC TRANSCRIPTION ENZYMES

Question 1

RNA Polymerase

Answer 1

Function: Recognize promotor sequence on DNA
Helicase activity - separates & unwinds base pairs
Sythesizes RNA in 5’-3’ direction
Nucleotidyl transferase activity - adds nucleoside triphosphates to RNA

Question 2

Sigma Factor

Answer 2

Function: helps RNA polymerase recognize promotors

Question 3

RNA Polymerase Holoenzyme

Answer 3

RNA Polymerase + Sigma Factor

Question 4

Promotor

Answer 4

Function: Located upstream a gene where RNA polymerase will attach (at -35 & -10 bp from transcription start site)

Question 5

RNA coding sequence

Answer 5

Function: where DNA is transcribed into RNA

Question 6

Terminator

Answer 6

Function: Sequence downstream coding sequence that specifies where transcription stops

Question 7

Prokaryotic Transcription Termination

Answer 7

Intrinsic
- Palindromic region in termination sequence form hairpins when transcribed
- CG rich region followed by U residues
- U’s form H bonds with template
- Stem loop structure de-stabilizes RNA polymerase
Extrinsic
- RHO protein attach to recognition site at RNA, move along following RNA Pol
- When RNA Pol stops at terminator, RHO will catch up and unwind DNA/RNA
- Once complete, RNA Pol, mRNA, and RHO are released