Transcription

Question 1

what is the use of transcription?

Answer 1

making RNA from a DNA template.
Protein synthesis occurs at the ribosome in the cytoplasm, but chromosomal DNA is too large to leave nucleus to supply it with the amino acid sequence for proteins. Thus, its copied into RNA and transported to ribosome

Question 2

what strand of DNA is copied by RNA polymerase?

Answer 2

Template (anti sense) strand

Question 3

what is the enzyme that transcribes the DNA

Answer 3

RNA polymerase

Question 4

what direction does RNA pol move in

Answer 4

3’ to 5’ direction meaning the RNA product will be antiparallel and complimetary to template

Question 5

what does RNA pol recognise that initiate transcription?

Answer 5

Recognises start signals - promotors regions which is the binding site for transcription factors and RNA pol

Question 6

what are the steps of transcription?

Answer 6

1. template recognition/intiation - RNA pol binds to DNA promotor region DNA is unwound
2. Elongation - RNA pol moves to synthesis the RNA, and unwound region moves
3. Termination - RNA pol reaches the end, recognises stop signals called terminators. RNA pol and RNA released and the DNA duplex forms.

Question 7

what happens to the RNA transcript after formed?

Answer 7

modified (splicing) e.g a 5’ cap and a poly A tail
- Coding regions are spliced
- introns are cut out
mRNA –> translation

Question 8

what is involved in transcription?

Answer 8

Transcription factors - important for initiation of the process
DNA
RNA polymerase
ATP (ADP and Pi)