RNA transcription

Question 1

Which bacterial RNA is most abundant?

Answer 1

rRNA, about 80%

Question 2

How big is tRNA?

Answer 2

4S, about 75 base pairs

Question 3

Which RNA types are only found in eukaryotes?

Answer 3

miRNA and snRNA

Question 4

What is the core enzyme of bacterial RNA?

Answer 4

ɑ2ββ’

Question 5

Which bacterial RNA polymerase subunit recognizes the promoter?

Answer 5

σ

Question 6

Which subunit contains the catalytic site?

Answer 6

β

Question 7

Which subunit binds the DNA template?

Answer 7

β’

Question 8

What is the role of the ɑ subunit of bacterial RNA polymerase?

Answer 8

Structural, may interact with regulatory proteins

Question 9

Which DNA strand has the same sequence as mRNA?

Answer 9

sense

Question 10

Which strand contains the promoter region?

Answer 10

sense

Question 11

What are the two elements of the prokaryotic promoter region?

Answer 11

-35 region and the -10 Pribnow sequence

Question 12

What is required for the sigma subunit’s DNA binding domain to be unmasked?

Answer 12

Must be bound to core RNA polymerase

Question 13

What is the first base transcribed?

Answer 13

purine triphosphate

Question 14

How long is the DNA-RNA hybrid during transcription elongation?

Answer 14

8 bp

Question 15

What sequence is necessary for rho independent transcription termination?

Answer 15

GC rich palindrome followed by UUUs

Question 16

What is the target of rifampicin?

Answer 16

It targets the beta subunit of bacterial RNA polymerase and inhibits the formation of the first phosphodiester bond.

Question 17

What is the structure and function of rho?

Answer 17

Hexameric helicase ATPase which terminates transcription by unwinding the RNA from DNA

Question 18

What type of drug is actinomycin A? What does it inhibit?

Answer 18

Intercalating agent which inhibits transcription and elongation by RNA polymerase. Not specific to prokaryotes or eukaryotes.

Question 19

Which RNA polymerase transcribes mRNA in eukaryotes?

Answer 19

RNA pol II

Question 20

Which subunit does eukaryotic polymerase lack?

Answer 20

Sigma

Question 21

What type of interactions govern transcription initiation?

Answer 21

polymerase-protein interactions

Question 22

What do inducible elements dictate?

Answer 22

Specificity of transcription

Question 23

What do constitutive elements regulate?

Answer 23

Rate of transcription

Question 24

What do basal elements provide?

Answer 24

Initiation site for transcription

Question 25

Which DNA sequence is found in the basal element?

Answer 25

TATA box

Question 26

How do enhancers affect transcription?

Answer 26

Can bind activators or repressors. Activators interact with TAF to enhance rate of transcription

Question 27

In what order do proteins form the Pol II pre-initiation complex.

Answer 27

Binding of TBP recruits TAFs and transcription factors IIA through IIH. Then polymerase II binds and the C-terminal domain of the large subunit is phosphorylated by TFIIH. which releases enzyme from the initiation site.

Question 28

What is the transcription complex which carries out elongation?

Answer 28

TFIIF and Pol II

Question 29

Why does transcription by Pol I and Pol III lack an elaborate control scheme?

Answer 29

The rRNAs (pol I) and tRNAs (Pol III) are needed in large amounts almost all the time.

Question 30

Split promoter

Answer 30

Promoter for Pol I transcription initiation with binding sites for upstream binding factor (UBF) and core binding factor (CBF).

Question 31

Internal promoter

Answer 31

Promoter for genes transcribed by Pol III located at +55 to +80. Binding of TFIIIA, B and C permits association of Pol III.

Question 32

α-amanitin

Answer 32

Preferentially inhibits RNA pol II, and to a lesser extend Pol III. Does not inhibit Pol I.

Question 33

Which type of RNA would be most transcribed in a cell poisoned with α-amanitin?

Answer 33

rRNA