Lesson: Chapter - 5

The Chemistry of Life

Of the 92 naturally existing elements on the Earth, only 25 play a role in the chemical processes of life. Of these 25, four elements constitute more than 98 percent of all biological matter: carbon (C), oxygen (O), hydrogen (H), and nitrogen (N). Virtually every important organic compound is made up of these four elements. The Big 4 of organic elements can be cut down even further to a Supreme 1: carbon is the most important biological molecule for life.

Carbon

Carbon is the central element of life. Its important role stems from its ability to form four chemical bonds with other elements at the same time:

Carbons often attach to other carbon atoms, forming long chains called hydrocarbons. These molecules get their name because the central carbons also bond to hydrogen:

Monomers and Polymers

Many biological molecules consist of basic units that are strung together to form long chains, much like beads are placed on a string to make a necklace. There can be some variation in these basic units, which are known as monomers. Two monomers connected to each other are known as a dimer; a chain of monomers is called a polymer.

Next to display next topic in the chapter.