1. Translation: 3 Steps

2. Translation occurs in three stages Key players –Ribosome –tRNAs –Translation factors The ribosome has three tRNA-binding sites –A, P, and E sites Figure 08.13: The relative sizes of components of the cellular translation machinery. Figure 08.14: Cartoon depicting the structure of an intact ribosome coupled to an mRNA.

3. Stage 1: Initiation requires base pairing between mRNA and rRNA Goal = bring all of the elements necessary for translation together into a giant cluster Ribosomal subunit to find ribosomal binding site = Shine-Delgarno sequence = initiation site Once the mRNA and small subunit are properly aligned, the first tRNA (initiator tRNA) binds to the AUG, and the large ribosomal subunit clamps down on the small subunit, forming an intact ribosome

4. Stage 2: Elongation amino acid is added to the carboxy terminus of the polypeptide in the A site Figure 08.15: The elongation cycle during translation.

5. Stage 3: Termination occurs when the bond holding the polypeptide to tRNA is hydrolyzed Stop codon Release factors Figure 08.15: The elongation cycle during translation.