This document summarizes key aspects of protein synthesis and translation. It discusses how genes are transcribed into mRNA, which is then translated into proteins using transfer RNA (tRNA) and ribosomes. The genetic code is explained, where codons in mRNA are translated to specific amino acids. tRNA molecules carry amino acids and recognize mRNA codons through complementary base pairing. Ribosomes provide the site where mRNA and tRNAs interact to polymerize amino acids into polypeptide chains based on the genetic code.

1. Genetics: Analysis and Principles Robert J. Brooker Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display CHAPTER 13 TRANSLATION OF mRNA Protein synthesis

3. 13-16 Figure 13.2 Overview of gene expression Note that the start codon sets the reading frame for all remaining codons

5. 13-13 Table 13-2

8. 13-27

10. 13-30 Figure 13.5 Condensation reaction releasing a water molecule Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Carboxyl group Amino group

11. 13-31 Figure 13.5 N terminal C terminal Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display

18. 13-38 Figure 13.8 Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display

19. 13-41 Wild type mutant A comparison of phenotype and genotype at the molecular, organismal and cellular levels Figure 13.9

26. 13-55 Figure 13.13 The amino acid is attached to the 3’ end by an ester bond tRNA charging

31. Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 13-60 Figure 13.15 Note: S or Svedberg units are not additive Synthesis and assembly of all ribosome components occurs in the cytoplasm

32. Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 13-61 Figure 13.15 The 40S and 60S subunits are assembled in the nucleolus Then exported to the cytoplasm Synthesized in the nucleus Produced in the cytosol Formed in the cytoplasm during translation

34. Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 13-63 Figure 13.16

36. Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Figure 13.17 Initiator tRNA See animation on your CD

39. 13-68 Figure 13.18 Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display

40. 13-69 Figure 13.18 70S initiation complex This marks the end of the first stage The only charged tRNA that enters through the P site All others enter through the A site Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display

45. 13-74 Figure 13.20 The 23S rRNA (a component of the large subunit) is the actual peptidyl transferase Thus, the ribosome is a ribozyme! Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display

46. 13-75 Figure 13.20 tRNAs at the P and A sites move into the E and P sites, respectively Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Max. 2 tRNAs bound to mRNA in a ribosome ! Peptide bond formation is catalyzed by rRNA, not by one of the proteins in the ribosome!

50. 13-79 Figure 13.21

53. Sequence of Triplet form the genetic code and the mutations in a gene : Frameshift Mutations: By insertion/deletion of 1 or 2 nucleotiden

54. Restoration of Frame shift

55. Mutations: Base changes Very harmful : - deletion / insertion of one base - deletion / insertion of two bases Especially in the beginning of a ORF/gene If at the end of a gene, the ‘shorter’ (or the to the-C-terminal-end-aberrant) protein can still be active Less harmful : - base substitution (another amino acid; but can also become a stop codon) - deletion / insertion of three bases (loss of an extra amino acid)

56. End of Chapter 13