Amino acids can react by condensation polymerisation to form biological proteins.

When dicarboxylic acid and diol monomers join through condensation polymrisarion, a polyester is formed.

A polymer is a long chain molecules made up of many smaller molecules. Polyamides, polypeptides and polyesters are all types of polymers.

Condensation polymers are made up of monomers connected through polar bonds: C-N and C-O.