the.com/molecular biology

means The study of life's machinery at the level of DNA, RNA, and proteins — explaining how organisms work by looking at the molecules that build and run them.

from The phrase 'molecular biology' is often credited to Warren Weaver, a Rockefeller Foundation science administrator, who used it in the late 1930s to describe a new push to fund physics- and chemistry-style precision applied to biological questions. The field itself took shape through the mid-20th century as scientists like Watson, Crick, and Franklin worked out the structure of DNA, turning biology from a largely descriptive science into one that could explain heredity and function in terms of actual molecular structure.