The set of three binding sites is labelled A, P, and E.

If a tRNA molecule's anticodon is complementary to an mRNA codon, the tRNA is held at the P and A sites.

The mRNA is shifted three nucleotides' length through the ribosome for each amino acid added.

Ribosomes have a set of three mRNA binding sites, and one tRNA binding site.

Peptidyl transferase creates the bond between neighboring amino acids using tRNAs stationed at the P and A sites.