Question

What is the difference between the P-site and A-site of a ribosome?

Answer 1

Feature	P-site	A-site
Full Name	Peptidyl-tRNA binding site	Aminoacyl-tRNA binding site
Primary Role	Holds the tRNA carrying the growing polypeptide chain.	Holds the incoming tRNA carrying a single amino acid.
Entry/Position	It is the middle site; the initiator tRNA binds here first.	It is the first site; all subsequent tRNAs enter here.
Bond Formation	It donates the protein chain to the amino acid in the A-site.	It receives the protein chain to form a new peptide bond.
Next Step	After donating the chain, the empty tRNA moves to the E-site.	After donating the chain, the empty tRNA moves to the E-site.