Covalent bonds place constraints on the shapes of biological molecules. as the size and complexity of a biomolecule increases, the chemical focus shifts from covalent bonds to noncovalent interactions. noncovalent interactions dictate the stable, native conformations of large macromolecules and polymers while permitting the flexibility necessary for their biological functions. what characteristics of weak noncovalent interactions enable the assembly, stability, and functions of biomolecules?