A peptide is considered to be any polymer of 40 or less amino acids linked in a chain. The carboxyl group of each acid is joined with the amino group of the next via a peptide bond: -OC-NH-. Peptide drugs can be chemically synthesized or recombinantly produced using a cell line such as E.coli. This means they are small biopharmaceuticals with less structural complexity than, for example, monoclonal antibodies. Peptide products may have a homogenous sequence, where all molecules in the product have an identical amino acid sequence, or they may be composed of peptides with heterogenous sequences. A heterogenous peptide product is a mixture of peptides with different sequences, such as glatiramer acetate.