Protein synthesis

The elongation cycle involves the binding of one amino acid.

It comprises 3 steps:

Step 1: Binding of a novel aminoacyl-tRNA at the A-site (hence, the A-site is named for the location where an amino acid binds)

At the beginning of the cycle, the P-site is occupied by the tRNA containing the peptidic chain being synthesized (the so-called P-site: peptidyl-tRNA).

The aminoacyl-tRNA binding to the A-site must pair with the corresponding codon in the mRNA, otherwise it is rejected.