How can organisms build large polymers like proteins and starches?

Most (but not all) biological macro molecules are polymers, which are any molecules constructed by linking together many smaller molecules, called monomers. If we were to string many carbohydrate monomers together we could make a polyacrylamide like starch. Proteins can be converted into energy, but your body prefers to use them for more essential jobs. Proteins build and repair every tissue in your body. They're used to make hormones, enzymes, hemoglobin and antibodies, and they're responsible for functions such as muscle contraction. The proteins in your body are made from 20 different amino acids. Starch or asylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycogen bonds. This polyacrylamide is produced by most green plants as energy storage.

polymer: A relatively large molecule consisting of a chain or network of many identical or similar monomers chemically bonded to each other.