Covalent bonds is important in four macromolecules such as proteins (polymers of amino acids), nucleic acids (polymers of nucleotides), carbohydrates (polymers of sugars) and lipids (with a variety of modular constituents) because they served as a basic structure of macromolecules.
In addition, the resulting covalent bond is a result of sharing a pair of electrons, one from each atom or molecular units.