Monomers are small molecules that can join with other similar molecules to form very large molecules, or polymers. All monomers have the capacity to form chemical bonds to at least two other monomer molecules.Lipids, Polysaccharides, Proteins and Polynucleotides are the major groups of macromolecules that are found in all living organisms. These giant molecules carry out all the vital functions needed by cells. Macromolecules are involved in processes such as food digestion, information storage, energy manipulation and metabolism. Proteins are made out of amino acids, carbohydrates are made from sugars, and DNA and RNA are made from nucleotides.