molecular biology

:  a branch of biology dealing with the study and understanding of biological activity and processes at the molecular level and especially the molecular basis of gene function and protein synthesis Molecular biology experiments proved that small pieces of DNA did sometimes move within or between chromosomes, thereby triggering changes in gene expression.—John Rennie, Scientific American, March 1993 The test is based on several recent advances in molecular biology, including the new insight that cells slip into the uncontrolled growth known as cancer through defects in specific enzymes that monitor and control division.—Lawrence K. Altman, The New York Times, 11 Oct. 1994