Transcription

Question 1

In which direction is RNA transcribed? And the DNA strand read?

Answer 1

RNA transcribed 5’ to 3’

DNA read 3’ to 5’

Question 2

The transcript created has the same sense as which strand? sense/non-sense

Answer 2

sense (non-template)

Question 3

Sigma factor

Answer 3

~ locates the transcriptional start site by recognising the promoter
~ interacts with DNA via several domains
~ bacteria

Question 4

Holoenzyme

Answer 4

a biochemically active compound formed by the combination of an enzyme with a coenzyme

Question 5

RNA pol I

Answer 5

~ eukaryotes
~ rRNA
~ found in nuclelous

Question 6

RNA pol II

Answer 6

~ eukaryotes
~ mRNA, snRNA, miRNA
~ found in nucleoplasm

Question 7

RNA pol III

Answer 7

~ eukaryotes
~ rRNA, tRNA, snRNA
~ found in nucleoplasm

Question 8

snRNA

Answer 8

small nuclear RNAs found in spliceosomes

Question 9

miRNA

Answer 9

regulate gene expression

Question 10

Core promoter elements

Answer 10

direct the binding of the transcription initiation complex

Question 11

TBP

Answer 11

TATA-binding protein

~ when it binds to TATA box it promotes the binding of TFIIB to the BRE sequence

Question 12

BRE

Answer 12

TFIIB recognition element

Question 13

Which RNA pols is TBP important for?

Answer 13

I, II and III

Question 14

Promoter clearance

Answer 14

displacement of the protein loop helps polymerase to break away from the promoter

Question 15

Comepare the functions of DNA gyrase and DNA topoisomerase I in E.coli.

Answer 15

~ DNA gyrase removes positive supercoils ahead

~ DNA topoisomerase I removes negative supercoils behind

Question 16

Histone chaperones

Answer 16

remove nucleosomes ahead of RNA polymerase and reassembles them behind it
e.g. FACT, Asf1, Spt6
~ EUKRYOTES

Question 17

RNA polymerase can stall because of…

Answer 17

~ a mis-inserted nucleotide

~ changes in supercoiling, the tension must be relieved

Question 18

Type I terminator

Answer 18

a.k.a. Rho-independant or Intrinsic terminators
~ no additional factors required for termination
~ in E.coli

Question 19

Type II terminators

Answer 19

a.k.a. Rho-dependent terminators
~ Rho factor is required for termination (requires ATP)
~ in E.coli

Question 20

Allosteric model of termination

Answer 20

RNA pol II continues to transcribe after the polyadenylation signal but the mRNA is cleaved at the poly(A) signal and the 3’ end of the mRNA is processed

Question 21

Torpedo model of termination

Answer 21

after cleavage at the poly(A) site, anything downstream of it is digested by Rat1 (5’ to 3’ endonuclease)

Question 22

Abortive initiation

Answer 22

the release of short RNAs by RNA pol after it fails to make full length RNA on its first attempt