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2. Presented By
Shaista perveen

3. Transcription
 Cellular process in which RNA synthesized using DNA
template known as Transcription.

4. RNA
 Ribonucleic acid
 Single stranded
RNA
mRNA rRNA tRNA

5. Role of DNA
 Only one strand of DNA used
 Template strand/Non coding strand
 Non template strnd/ coding strand

6. Enzymes and factors
Eukaryotes prokaryotes
 RNA polymerase
 RNA polymerase I
 RNA Polymerase II
 RNA PolymeraseIII
 General transcription
factor
 RNA Polymerase
 Only one type of RNA
polymerase
 Sigma factor

7. Steps of transcription
 Initiation
 Elongation
 Termination

8. Initiation
 RNA Polymerase binds to DNA
Promoter
 Initiation require special DNA sequence
 Binds with +1 site
 Recongnize DNA strand

9. Intiation
Eukaryotes Prokaryotes

10. Starting the prpcess

11. Elongation
 Core enzyme move over the template strand
 Transcription bubble moves down the DNA
 It leaves the growing strand

12. Termination
Eukaryotes Prokaryotes
 Polyadenylation signal
(AAUAAA) transcribed
 Reaches 10-35 bp downstream
 RNA transcript released
 Series of GC bp
 Followed by AT bp
 Hairpin U shaped
 U ribonucleotide

13. Transcription in prokaryotes

14. Transcription in eukaryotes

15. Post transcriptional processing
EUKARYOTES Prokaryotes
 mRNA travel from nucleus to
cytoplasm
 Cap
 5` end in the form of
7methylGTP
 Tail
 linked to 3`end in the form
of PolyA tail
 mRNA directly released into
cytoplasm
 No Cap and tail formation

16. Mechanism of capping

17. steps
 Phosphatase enzyme- removed 5` terminal phosphate
 Guanosyl transferase- Produce diphosphate
 Methyl transferase- transfer methyl group from S-
adenosyl methionine to guanine ring
 Methyl group added to 2`OH of ribose
 Protect from endonucleases

18. Mechanism of addition of tail
 Polyadenylation sequence( 5`-AAUAAA-3`)
 Cleavage site ( 5`-CA 3`)
 RNA Polymerase II has two factors
 CPSF
 CStF
 Cleavage occure , PAP fomed
 Add 200 adenine unit to new 3` tail
 Protect from endonucleases