Transcription

Question 1

What is the difference between DNA and RNA?

Answer 1

DNA: double stranded, large, deoxyribose, in nucleous, nitrogenous bases are T, G, A, C
RNA: single stranded, small, ribose, in cytoplasm, nitrogenous beset A, C, G, U

Question 2

What is the role of RNA?

Answer 2

Storage and transmission of information

Involved in protein synthesis

Question 3

What types of different RNA are there?

Answer 3

mRNA
tRNA
rRNA
snRNA, snoRNA, miRNA

Question 4

Describe transcription

Answer 4

RNA synthesis
RNA polymerase synthezises 
A strand of DNA is template
Only one particular gene/group of genes at the time
mRNA is translated into proteins

Question 5

Describe the characteristics of RNA polymerase

Answer 5

Needs a DNA template, NTPs, Mg++
NO need for primers
Built in 5'-3' direction
No proofreading exonuclease activity
High processivity

Question 6

What is the transcription bubble?

Answer 6

The area containing RNA polymerase, DNA and the newly forming RNA
Enzyme

Question 7

What are the parts of the transcription bubble?

Answer 7

Has a core or “body”
The sigma subunit that binds to the core and directs the enzyme to the specific binding sites of DNA to initiate transcription

Question 8

What is a promoter?

Answer 8

Specific sequences in DNA that direct the RNA polymerase initiating transcription

Question 9

What is a consensus sequence?

Answer 9

Variable sequences found at -35 TTGACA and -10 TATAA

determines the efficacy and binding of RNA polymerase

Question 10

What are the stages of initiation?

Answer 10

Binding-RNA polymerase is directed of sigma subunit and binds to promoter
Close complex formation (intact DNA)
Initiation of transcription
Promoter clearance- transcription complex moves away from promoter
Sigma unit dissociates and polymerase enters elongation

Question 11

What are the three stages of transcription?

Answer 11

Initiation
Elongation
Termination

Question 12

Describe elongation

Answer 12

Synthesis of the RNA
Introducing large numbers of nucleotides
DNA is unwound, forming a bubble
High error rate
Generate positive and negative supercoils
No exonuclease in RNA polymerase

Question 13

Describe termination

Answer 13

certain DNA sequences pauses or ends transcription
(Rho) dependent
(Rho) independent creates a hairpin making the structure unstable=dissociation