Translation in prokaryotes and eukaryotes

translation in prokaryotes and eukaryotes in details , with newest informations available with proper diagram

1. Process of Translation Presented by – Dwijottam Sarma Bordoloi (17/BBT/20) Ashish Pratim Mahanta (17/BBT/60) Course : Biotechnology Dept. Of Applied Biology

2. CONTENTS Introduction Translation in Prokaryotes Translation in Eukaryotes Differences between Prokaryotic and Eukaryotic translation Conclusion References

3. INTRODUCTION Translation process by which mRNA directs protein synthesis with the assistance of tRNA . Last and most important phase of Central Dogma. Process is somewhat similar despite having certain differences in case of both prokayotes and eukaryotes. mRNA is decoded in a ribosome to produce a specific sequence of amino acids. Has 3 steps: ( i ) Initiation, (ii) Elongation, (iii) Termination

4. Takes place from 5’ to 3’ direction. Elements involved : mRNA tRNA Ribosome Amino acids Translation factors [IF’s, Ef’s , RF’s]

5. TRANSLATION IN PROKARYOTES

6. Initiation : (a) tRNA charging – Addition of adenylylated amino acid to tRNA Adenylylation of amino acid Transfer of adenylylated a.â to tRNA Transfer of adenylylated a.â to tRNA Aminoacyl tRNA synthetase

7. (b) Initiation complex formation – 30s initiation complex 70s initiation complex INITIATION FACTORS INVOLVED : IF1, IF2 ( GTPase activity), IF3

8. 2. Elongation : Elongation factors involved – EF-TU, EF-G, EF-Ts (all GTPase proteins) EF-TU attach to amino acyl tRNA tRNA attach to A site, EF-TU bind to EF-TU binding site of ribosome EF-TU hydolyses GTP to GDP and Pi Codon-Anticodon bond is formed EF-TU fall off, carrying GDP EF-Ts hydrolyses its GTP to release energy to form bond between GDP and a Pi and make GTP again in the EF-TU that fell off

9. Peptidyl transferase

10. 3. Termination : Occurs when a stop codon (UAA, UAG,UGA) is reached. Termination factors involved – RF1, RF2, RF3, RRF (also EF-G and IF3) [RF1 recognizes UAA and UAG, RF2 recognizes UAA and UGA]

11. RF3 comes and bind to 50s subunit, contains GDP RF1 detches from A site, energy is released, GTP is formed A site free RRF binds to A site; EF-G binds to ribosome to translocate IF3 attach to E site 50s subunit dissociates RRF signals the release of mRNA

12. TRANSLATION IN EUKARYOTES

13. 1. Formation of 43 s Preinitiation complex eIF3 & eIF5 binds to exit (E) site. eIF1 blocks Amino acyl tRNA addition (A) site. eIF2 carrying GTP binds to met tRNA and get attached to the peptide bond formation (P) site. INITIATION

14. 2. Attachment of mRNA eIF4 complex (A/G/E/B/F) will bring and attach to mRNA (5` methylated guanine capping with eIF4E ) Poly A tail is folded back to form loop like structure.

15. 3 . Scanning for the START codon Poly A tail moves to recognize the START codon for the arrachment with tRNA .

16. 4 . Assembly of large subunits eIF5B along with GTP carries and 60s subunit of RNA & get it attached to tRNA removing eIF1 , eIF5 , eIF3 , eIF2 – GDP.

17. Elongation by EF1A

18. Cotranslational translocation Eukaryotes has compartmentalization , different organelle system ; for delivery of a protein to the distinct organelle need to add / modify/ fold them which needs so much time ; to consume less they do co-translational translocation ( insertion of polypeptide chain into ER lumen) First 10-20 polypeptide acts as signal sequence will attract receptor protein (SRP) SRP binds to SRP receptor found in RER translocon channel. Ribosome near translocon channel start adding more no. of amino acid and insert polypeptide to ER lumen Polypeptide chains are restricted by signal peptidase.

19. Post translocation Modification Protein should be modified cause it is very important as different organelle take protein in different forms. Many chemical modifications takes place in GOLGI BOGY.

20. TERMINATION eRF3(hbs1) or eRF1(Dom34) along with GTP binds to the A site and terminate the polypeptide chain hydrolysing GTP to GDP along with a water molecule. Rli 1 factor carries ATP which binds to ERF3/ERF1 hydrolyses and ribosome recycling takes place.

21. DIFFERENCES P PROKARYOTES EUKARYOTES 70s ribosome is involved. Transcription and translation take place simultaneously. Translation is polycistronic . Initiator protein – f-Met Requires 3 release factors (RF1, RF2, RRF) Rate : 20 a.ȃ /sec No modification of polypeptide chain take place. 80s ribosome is involved. Transcription and translation don’t take place simultaneously. Translation is monocistronic . Initiator protein – Met Requires 2 release factors (eRF1, eRF3) Rate : 1 a.ȃ /sec Modification of polypeptide chain take place in golgi bodies

22. CONCLUSION Translation involves 3 phases namely Initiation, Elongation and Termination, be it Prokaryotes or Eukaryotes. Despite having differences in both of the translation types, they are functionally very similar and their ultimate goal is the same, i.e. To make proteins. Proteins are the crucial elements that our body uses all throughout the life cycle and they are synthesis solely by the process of translation.

23. REFERENCES Websites – www.wikipedia.org/wiki/translation www.youtube.com / shomu’s_biology www.softschool.com/science/biology Book – Life Sciences, Fundamentals and Practice – I (Fifth edition) Pathfinder publication, New Delhi, India By Pranav Kumar and Usha Mina

24. Thank You!