They are very influential in cellular energy metabolism, and also the building blocks for reactions which assemble macromolecules. When carbonyl molecules and hydroxyls combine, they form the carboxyl group. The carboxyl group is the primary group of organic acids. Carboxyls are part of amino acids, fatty acids, along with many other organic acids which form the fuel substances, and also enter into linkages of larger assemblies. The amino group has the ability to act as a base inside organic molecules.
Amino acids contain an amino group at one end, and a carboxyl at the opposite end.
There is a condensation reaction between the amino and the carboxyl which forms a peptide linkage which ties amino acids into the backbone chain of proteins. The taking up of the hydrogen ions is what allows the amino to act as a base. If you were to remove the hydronium ion, it would raise the pH of the medium. Phosphates have many important roles in biological molecules. One of the most important is the ability of the phosphate group to form chemical bridges which link the organic building blocks into much larger molecules.