Amino acids, peptides and proteins some terminology

Amino acids, peptides and proteins some terminology... 

A brief introduction to the ribosome system is necessary to acquaint the reader with some terminology. The ribosome is the site of protein biosynthesis. Its substrates otc aa-tRNAs that cycle on and off, transferring their amino acids into the nascent protein chain according to information encoded by mRNA. Transfer RNA binds to ribosomes in at least two functionally distinct sites, which are defined in terms of peptide bond formation. The peptide donor (a pep-tRNA) is bound in the P site during peptide bond formation the peptide acceptor (an aa-tRNA) is bound in the A site. There is also some functional-- evidence of a third tRNA-ribosome binding conformation. 

---