Molecular biology is the study of the structure and function of the complex chemicals that are found in living things. + molecular biologist molecular biologists mo·lecu·lar bi·olo·gist This substance has now been cloned by molecular biologists. Field of science concerned with the chemical structures and processes of biological phenomena at the molecular level. Having developed out of the related fields of biochemistry, genetics, and biophysics, the discipline is particularly concerned with the study of proteins, nucleic acids, and enzymes. In the early 1950s, growing knowledge of the structure of proteins enabled the structure of DNA to be described. The discovery in the 1970s of certain types of enzymes that can cut and recombine segments of DNA (see recombination) in the chromosomes of certain bacteria made recombinant-DNA technology possible. Molecular biologists use that technology to isolate and modify specific genes (see genetic engineering)
the branch of biology that studies the structure and activity of macromolecules essential to life (and especially with their genetic role)