1. ترجمه ( Translation )

2. Transcription and Translation

3. چه اندامک ها و ملکولهایی در ترجمه نیازند؟ mRNA Ribosomes + reticulum endoplasmic tRNA + Amino acids ATP Translation Factors

4. mRNA در پروکاریوت ها مجموعه ی ژنهایی که توام و تحت کنترل یک سیستم نظارتی بیان می شوند اپرون نامیده می شوند. حاصل بیان اپرون ها mRNA است که به چند پروتئین ترجمه خواهد شد لذا به آن mRNA پلی سیسترونی گفته می شود.

5. The roles of RNA in protein synthesis

7. tRNA structure 73 - 93 nt. long. 30 - 100 tRNA genes per cell. Link codons to amino acids. is done by aminoacyl tRNA synthetases (AARS) 64 codons (3 stops) 20 amino acids

8. The aminoacyl-tRNA synthetase reactions Each AARS is specific for an amino acid. but Can bind multiple tRNAs.

9. Ribosome structure in prokaryotes & eukaryotes

10. Ribosome The ribosome has three binding sites for tRNA The P site The A site The E site EPA P site (Peptidyl-tRNA binding site) E site (Exit site) mRNA binding site A site (Aminoacyl- tRNA binding site) Large subunit Small subunit Schematic model showing binding sites. A ribosome has an mRNA binding site and three tRNA binding sites, known as the A, P, and E sites. This schematic ribosome will appear in later diagrams. (b)

11. مراحل ترجمه آغاز (Initiation ) پیشرفت ( Elongation ) ختم ( Termination )

12. Translation initiation - where to start? Prokaryotes: the Shine-Dalgarno sequence AAGGAGG consensus 5 - 13 nt. from start codon (AUG, GUG, UUG) Eukaryotes: the scanning mechanism 5’ of mRNA is recognized (the m7G cap) First in-context AUG is used. Context = GCCACCaugG

13. Scanning mRNA for AUG

14. کمپلکس شروع در پروکاریوت ها mRNA Small ribosomal subunit Initiation factor 2 (IF-2) and GTP tRNA i Met IF-1 and IF-3 are also required.

15. The start codon is recognized by methionyl-tRNA i Met

16. Initiation of bacterial protein synthesis IF1 associates with the 30S ribosomal subunit in the A site and prevents an aminoacyl-tRNA from entering. It modulates IF2 binding to the ribosome by increasing its affinity. It may also prevent the 50S subunit from binding, stopping the formation of the 70S subunit. It also contains a β-domain fold common for nucleic acid binding proteins. IF2 binds to an initiator tRNA and controls the entry of that tRNA into the ribosome. IF2, bound to GTP, binds to the 30S P site. After associating with the 30S subunit, fMet-tRNA f binds to the IF2 then IF2 transfers the tRNA into the partial P site. When the 50S subunit joins, it hydrolyzes GTP to GDP and P i, causing a conformational change in the IF2 that causes IF2 to release and allow the 70S subunit to form. IF3 is required for the 30S subunit to bind to the initiation site in mRNA. In addition, it has several other jobs including stabilization of free 30S subunits, facilitation of 30S subunits binding to mRNA and checking for accuracy against the first aminoacyl-tRNA. It also allows for rapid codon-anticodon pairing for the initiator tRNA to bind quickly to. IF3 is required by the small subunit to form initiation complexes, but has to be released to allow the 50S subunit to bind.

17. Initiation of translation in eukaryotes Lodish, Molecular Cell Biology

18. Intiation of translation in eukaryotes -2 Lodish, Molecular Cell Biology eIF-2 is a translation control point in eukaryotes

19. Elongation Aminoacylated tRNAs are brought to the ribosome by elongation factor Tu (EF-Tu):

20. Translation elongation

21. Release factors recognize stop codons Termination

22. Termination of translation in eukaryotes Lodish et al. Molecular Cell Biology

24. Ribosome recycling

25. مکانیسم اثر آنتی بیوتیک ها در درمان عفونت های باکتریایی

26. Translation Inhibitors are important antibiotics

27. Polypeptide synthesis always begins in the cytosol Synthesis finishes in the cytosol unless the polypeptide signals the ribosome to attach to the ER Polypeptides destined for the ER or for secretion are marked by a signal peptide A signal-recognition particle (SRP) binds to the signal peptide The SRP brings the signal peptide and its ribosome to the ER Targeting Polypeptides to Specific Locations Ribosomes mRNA Signal peptide Signal- recognition particle (SRP) SRP receptor protein CYTOSOL ER LUMEN Translocation complex Signal peptide removed ER membrane Protein