Four main classes that define a macromolecules are
- Protein
- carbohydrates
- lipids
- nucleic acid
EXPLANATION:
Macro-molecule is a large molecule which can contain more than 100's and 1000's of atoms. They are different from the smaller molecules and each macro-molecule does more than one function.
Macro-molecules are made up of single elements of monomers joined using covalent bonds and a large polymer is formed. For example, one molecule of polyethylene which is plastic has more than 2500 methylene groups, each one of them has two hydrogen and one carbon atoms.