molecule
Meaning of molecule: Molecules form when atoms bond together, and biological versions such as proteins and DNA can involve thousands of atoms arranged in specific structures.
Definition of molecule
A molecule is the smallest unit of a substance that still displays all of that substance's chemical properties. It is formed from two or more atoms held together by chemical bonds, and the specific atoms involved and their arrangement determine the molecule's identity and behavior.
A molecule can be made of a single type of atom, such as an oxygen molecule formed from two oxygen atoms, or of different types of atoms bonded together, such as a water molecule, which contains two hydrogen atoms and one oxygen atom. Simple molecules like these contain only a few atoms.
Biological molecules, including proteins, DNA, and RNA, are far larger and more complex, often containing many thousands of atoms arranged into specific three dimensional shapes that determine how the molecule functions within a cell, and understanding this structure is often central to understanding a molecule's biological role.
Used in a sentence
The laboratory identified a small molecule capable of binding to the target protein.
Good to know
A molecule's biological function depends heavily on its three dimensional shape as well as its chemical composition, so two molecules built from similar atoms can behave very differently depending on how those atoms are arranged.
Word origin
Where “molecule” comes from
Formed from Latin moles, meaning mass, combined with the diminutive suffix -cula, together suggesting a small mass.