Hydrocarbons, made up completely of carbon and hydrogen atoms, make delightful combustion fuels (such fuels include propane, butane, and the bulk of commercial gasoline). But can you shape a living organism out of only burning fuels? Probably not. Most large organic molecules in fact cover many types of atoms outside just carbon and hydrogen. These extra atoms allow for functionality not typically seen in hydrocarbons.

Large biological particles are generally calm of a carbon skeleton (made up of carbon and hydrogen atoms) and some other particles, including oxygen, nitrogen, or sulfur. Often, these extra atoms appear in the context of useful groups. Functional groups are chemical motifs, or designs of atoms, that display consistent “function” (properties and reactivity) irrespective of the exact particle they are found in. Biological particles can contain many dissimilar types and combinations of useful groups, and a biomolecule’s specific set of groups will affect many of its possessions, including its structure, solubility, and responsiveness.

A few of the most significant functional groups in biological particles are shown in the table below. Useful groups can be classified as hydrophobic or hydrophilic founded on their charge and polarity characteristics. The only aquaphobic group below is the methyl  group, which is nonpolar. The residual six functional collections in the table all have varying degrees of hydrophilic character.