The study of the chemical structures and processes of biological phenomena at the molecular level; the discipline is particularly concerned with the study of proteins, nucleic acids, and enzymes, the macromolecules essential to life processes. It seeks to understand the molecular basis of genetic processes. Techniques used include X-ray diffraction and electron microscopy.
(Source: GILP96)
the branch of biology that studies the structure and activity of macromolecules essential to life (and especially with their genetic role)