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

3. Prototrophs
mutation
Auxotrophs

4. The Structure and Function of Proteins

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

8. Protein: Levels of structural organization

11. The Genetic Code and Translation

12. The Breaking of the Genetic Code

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

14. 1. . 3 2 1
All these experiments used a cell free system. 4 5
ppt. protein

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

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

17. Amino Acid
Transfer RNA
ribosome

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

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

20. Genetic Code Table
1968
Wobble
Degeneracy & mRNA

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

22. The process of translation

23. mRNA sequences

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

25. Step 1 Binding of amino acid to tRNA

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

27. Step 2: Initiation of Translation
Bacterial Initiation
IF3

28. 30S

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

30. Eukaryotic Initiation
Kozak
Eukaryotic Initiation
key differences

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

32. Elongation continues on ribosomes

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

34. 6.
Lipoprotein
Glycoprotein

35. Many antibiotics target prokaryotic translation.

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

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

38. 1. 2.

39. 3.

40. 4.

41. 5.

42. 6. Protein Modifications

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