- For protein synthesis to begin, Initiation Factors assemble the small ribosomal sub-unit, mRNA, initiator tRNA, and large ribosomal sub-unit
- Small ribosomal sub-unit attaches to the mRNA near the start codon (AUG)
- Initiator tRNA (UAC) binds to the codon
- a large ribosomal sub-unit joins to form the active ribosome
- The 3 binding sites are A (Amino acid), P (Peptide), E (Exit)
Elongation:
- Protein synthesis occurs
- Polypeptide becomes longer
- when the initiator tRNA is bound to the ribosome, the A site is occupied by the tRNA
- Anti-codon base pairs with the second mRNA codon , ribosome can link the second amino acid together
- Peptide bond forms between the first and second amino acids
- resulting dipeptide is attached to the tRNA at A site
- the mRNA moves along by one codon and enters the P site
- tRNA carrying the next amino acid enters the A site
- the polypeptide chain is transferred to the amino acids in the A site
- mRNA moves along by one codon and the tRNA which no longer carries an amino acid exits from the E site
- the phase begins when a stop codon is reached on the mRNA
- the polypeptide and the components of translation are separated (KA-BOOM)
- A release factor (protein) cuts the polypeptide from the last tRNA
- the polypeptide will then fold into a 3D shape which is ready to perform its cellular activities
