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Protein Synthesis

This PowerPoint presentation provides an introductory overview of protein synthesis, highlighting the role of genes, DNA, RNA, and ribosomes. It covers topics such as transcription, translation, tRNA structure, ribosome attachment, and protein synthesis initiation and elongation.

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Protein Synthesis

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  1. Protein Synthesis Computer Filename: Protsyna.ppt Material for Introductory Microbiology

  2. Overview • Genes are composed of DNA within the chromosome • Genes code for proteins • DNA is transcripted into RNA • RNA is translated into protein by ribosomes • Genes regulated by control of RNA production

  3. Lecture Outline • tRNA structure • adding amino acids to tRNA • ribosome structure • ribosome attachment • protein synthesis :initiation, elongation, attachment Protein synthesis

  4. Concepts from OAC • Structure & Function of DNA & RNA • Genetic code • Transcription & translation • Protein synthesis

  5. Background Terms & Concepts • Structure of DNA & RNA • Ribosomes • Enzymes

  6. CODONS • sequences of three adjacent nucleotides that code for one amino acid or polypetide termination • 64 codons encrypt of ~ 20 amino acids • degenerate ACU, ACC,ACA, ACG threonine • Start codon AUG (also codes for methionine) • Stop codon UAA,UAG,UGA (nonsense codons)

  7. Interpreting the Genetic Code • Two step process :Transcription -translation • Transcription DNA --> RNA • Translation RNA--> protein

  8. Transcription • occurs in nucleus • DNA unravels- single strand • RNA Polymerase binds to Promotor site • Reads to stop codon • assembles complementary single strand of RNA (primary RNA) • Disengages when reaches stop codon Production of an RNA copy of the gene

  9. Ribosomal RNA • called rRNA • found in Ribosomes • catalytic site • provides site for protein assembly • ribosomal structure different in eukaryotes and prokaryotes

  10. Prokaryotic ribosome • 70S • large ribosomal subunit 50S 1,600,000 • 34 proteins • 5S RNA 120 nucleotides • 23S RNA 2900 nucleotides • Small ribosomal subunit 30S 900,000 • 21 proteins • 16s RNA 1540 nucleotides

  11. Eukaryotic ribosome • 80 S 4,200,000 • large subunit 60S 2,800,000 • 49 proteins • 5s RNA 120 nucleotides • 28s RNA 4700 nuclotides • 5.8 s RNA 160 nuclotides • Small subunit 40S 1,400,000 • 33 proteins • 18s RNA 1900 nuclotides

  12. Transfer RNA • called tRNA • Smaller than mRNA or rRNA • found in cytoplasm • 40 different kinds of tRNA • transports amino acids to ribosome • positions amino acids on elongating polypeptide

  13. tRNA

  14. tRNA

  15. tRNA Activating Enzymes • Specific for each type of tRNA • called tRNA synthetase • binds to specific amino acid • binds to specific nucleotides in tRNA • covalently crosslinks amino acid to free 0H • water is lost

  16. Large Ribosomal Subunit Two tRNA binding sites

  17. Polysomes

  18. Ribosomes on Rough ER

  19. EM of Ribosomes

  20. Protein Synthesis • Formation of an initiation complex • Chain elongation • Chain termination

  21. Concept Map:Protein Synthesis

  22. Initiation of Protein Synthesis

  23. Initiation 2

  24. Initiation 3

  25. Initiation 4

  26. Internal Ribosome Entry Sequences PicroRNA viruses cleave eIF4g and use IRES

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