Light micrograph of p-Methylbenzhydrylamine, an inert resin used in solid phase peptide synthesis; an amide group is attached to the resin allowing further amino acids to be built up in a chain. There are twenty standard amino acids, which form the basic building blocks of all living matter. Amino acids combine to form proteins. The linkage between two amino acids is called a peptide bond & the amino acids so joined are referred to as peptides. A protein molecule consists of anywhere from a hundred to several thousand amino acids, linked together to form polypeptide chains. Rheinberg illumination. Magnification: x200 at 35mm size.