<prompt> Collagen has which amino acid?TryptophanGlycineTheonineTyrosine  <response>: Each polypeptide chain of collagen has about 1000 amino acid residues. amino acid composition of collagen is quite unique. About 33 of the amino acids are glycine, that is, every third residue is glycineRef: DM Vasudevan, 7th edition, page no: 720 