All of life's processes involve chemical reactions - the combining, exchanging, and breaking apart of atoms and molecules of a few basic substances. The video explains that all materials are made up of combinations of elements. Only 30 of the 92 naturally-occuring elements are important biologically.
Special emphasis is given to carbon, hydrogen, oxygen, nitrogen, sulfur, and phosphorous.
The biological importance of each biochemical group in the structure and function of all living things is considered.