Most important biological molecules are polymers.
Biological polymers include proteins,
carbohydrates and lipids.
Polymers are made from smaller molecules called monomers.
Biological molecules are based on the element
carbon. It has the ability to form 4 bonds with itself
or with other elements.
The bonds that hold monomers together are often
formed by condensation reactions.
Organisms constantly take in a range of chemicals,
using them to make other substances that they need.