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Outline

Outline. One enzyme ??. One gene Structure and function of proteins Genetic Code Process of translation Iniation Elongation Termination Release modification. Prototrophs. mutation. Auxotrophs. The Structure and Function of Proteins. Amino Acids-R groups. Nonpolar, aliphatic

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Outline

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  1. Outline One enzyme ?? • One gene • Structure and function of proteins • Genetic Code • Process of translation • Iniation • Elongation • Termination • Release • modification

  2. Prototrophs mutation Auxotrophs

  3. The Structure and Function of Proteins

  4. Amino Acids-R groups • Nonpolar, aliphatic • Polar, uncharged • Aromatic • Positively charged • Negatively charged

  5. Protein: Levels of structural organization

  6. The Genetic Code and Translation

  7. The Breaking of the Genetic Code

  8. Experiments that “broke the genetic code” • 1. Homopolymer experiment • 2. Known RNA sequences and ribosomal bound tRNA

  9. 1. . 3 2 1 All these experiments used a cell free system. 4 5 ppt. protein

  10. 1. Homopolymer experiment In 1961 1 hot amino acid translation 19 cold amino acids Cell free system 20X each a different “hot amino acid

  11. 2. Known mRNA sequences + Ribosomal bound tRNA Amino acid This is transfer RNA Anti-codon

  12. Amino Acid Transfer RNA ribosome

  13. 2. Known mRNA sequences + Ribosomal bound tRNA Amino acid This is transfer RNA Anti-codon

  14. Mix with Codon of mRNA Isolate ribosome bound tRNA Analyze amino acid

  15. Genetic Code Table 1968 Wobble Degeneracy & mRNA

  16. Isoaccepting & tRNAs Different tRNAs accept same amino acid!

  17. The process of translation

  18. mRNA sequences

  19. Translation • 1. Binding of amino acids to tRNA • 2. Initiation • 3. Elongation • 4. Termination • 5. Peptide Release • 6. Protein modification

  20. Step 1 Binding of amino acid to tRNA

  21. It takes two steps to “charge” the tRNA Aminoacyl-tRNA-synthetase Amino acid+ATP tRNA is charged

  22. Bacterial Initiation Step 2: Initiation of Translation IF3

  23. 30S

  24. Note 3 ribosomal sites P A E 70S E A

  25. Kozak Eukaryotic Initiation key differences

  26. 3. ELONGATION: look at the “EPA” sites

  27. Elongation continues on ribosomes

  28. Steps 4 and 5: UAA UAG UGA Termination and Release

  29. 6. Lipoprotein Glycoprotein

  30. Many antibiotics target prokaryotic translation.

  31. Tetracyclines Chloramphenicol Streptoymycin Erythromycin Bind and block bacterial ribosomes “A” site Binds to large subunit; blocks peptide formation Blocks initiation step Blocks translocation step Antibiotics and Translation

  32. For your review: Summary of important steps involved in translation

  33. 1. 2.

  34. 3.

  35. 4.

  36. 5.

  37. 6. Protein Modifications

  38. Eukaryotic translation is very similar except: • More IF’s • Kozak sequence • 5’CAP • 3’poly-A tail

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