The branch of biology that studies the structure and activity of macromolecules essential to life (and especially with their genetic role) WordNet 3.0 & Open English WordNet

Molecular biology is a branch of biology that seeks to understand the molecular basis of biological activity in and between cells, including biomolecular synthesis, modification, mechanisms, and interactions. Wikipedia

Branch of biology that deals with the molecular basis of biological activity Wikidata

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. OmegaWiki

The branch of biology that studies the macromolecules of life, such as proteins, lipoproteins and nucleic acids. Wiktionary

Branch of biology. Wiktionary (translation)