This video explains how DNA works and what it does, relating it to an instruction manual for building an organism. [4:29] Followed by a short quiz and a list of additional resources to explore.

All cells, organs and tissues of a living organism are built of molecules. Some of them are small, made from only a few atoms. There is, however, a special class of molecules that make up and play critical roles in living cells. These molecules can consist of many thousands to millions of atoms. They are referred to as macromolecules (or large biomolecules).