Final answer:
The first amino acid added to a polypeptide chain is often Methionine.
Step-by-step explanation:
The first amino acid added to a polypeptide chain is often Methionine. It is encoded by the codon AUG, which is also the initiation codon. Methionine is usually removed enzymatically before the completion of the polypeptide chain, but it is still the first amino acid in the chain.