(6) Transcription: elements, stages, mechanism, reverse transkr.

Question 1

Transcription

- necessary factors

Answer 1

1. DNA template
2. 1 Promotor with TATA-box, to which RNA-Po. (in prokaryotes) or transcription factors (in eukaryotes) bind
3. 2 Operon (in prokaryotes) – a complex of promoter, operator, structural genes, terminator and regulator which act in a coordinate manner and produce mRNA
4. four ribonucleoside triphosphates (A, G, U, C) = building blocks
5. RNA polymerase (Eukaryotes: I.- rRNA, II.- mRNA, III. -tRNA) = form phosphodiester bonds
6. Topoisomerase
7. Helicase
8. Transcription factors (in eukaryotes, help the binding of RNA-pol II to the promoter)
9. Energy/ ATP

Prokaryotes:

8. RNA-holoenzyme, consits of 2 forms of RNA-polymerase:
   - core enzyme: has catalytic activity, but cannot recognize promotor
   - σ (sigma) factor: recognizes and binds promoter

Question 2

Transcription

Definition

Answer 2

the process by which genetic information from DNA is enzymatically transfered/copied into a complementary RNA molecule

Question 3

Transcription:
antisense strand
sense strand
complementary
direction of production

Answer 3

• mRNA is single stranded
• аntisense strand: the transcribed DNA strand
• sense strand: the nontranscribed DNA strand
• antisense and sense strands are complementary
• antisense strand and mRNA are complementary

It is produced continuously in direction 5- 3, which is
the 3- 5direction of the template DNA strand