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Genetic Code and Translation

Genetic Code and Translation. Outline. The Breaking of the Genetic Code Examples of two experimental approaches Concepts and Terms related to genetic code Wobble Degeneracy isoaccepting Translation prokaryote eukaryotes. The Genetic Code and Translation.

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Genetic Code and Translation

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  1. Genetic Code and Translation

  2. Outline • The Breaking of the Genetic Code • Examples of two experimental approaches • Concepts and Terms related to genetic code • Wobble • Degeneracy • isoaccepting • Translation • prokaryote • eukaryotes

  3. The Genetic Code and Translation

  4. The Breaking of the Genetic Code

  5. Experiments that “broke the genetic code” • 1. Cell Free experiments • Applied to the Homopolymer experiment • 2. Known RNA sequences and ribosomal bound tRNA

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

  7. Application of experimental design 1 hot amino acid translation + 19 cold amino acids Cell free system 20X each a different “hot amino acid

  8. 2. Known mRNA sequences + Ribosomal bound tRNA Amino acid This is transfer RNA Now link this idea to The genetic code table Anti-codon

  9. Amino Acid Transfer RNA ribosome

  10. Mix with Codon of mRNA 2. EXPERIMENT Isolate ribosome bound tRNA Analyze amino acid

  11. Close up of a possible result:

  12. Genetic Code Table 1968 Wobble Degeneracy & mRNA

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

  14. The process of translation

  15. We will approach our discussion of translation as a “Nonoverlapping Code” mRNA sequences

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

  17. Step 1 Binding of amino acid to tRNA

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

  19. Up close view of “charged” tRNA

  20. Bacterial Initiation Step 2: Initiation of Translation IF3

  21. 30S

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

  23. Kozak Eukaryotic Initiation key differences

  24. Peptidyl transferase 3. ELONGATION: look at the “EPA” sites

  25. Up close view of translation

  26. Elongation continues on ribosomes

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

  28. Animation of Translation http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter14/animations.html See chapter 15

  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. Review: The Structure and Function of Proteins

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

  34. Protein: Levels of structural organization

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

  36. 1. 2.

  37. 3.

  38. 4.

  39. 5.

  40. 6. Protein Modifications

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

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