Life as we know it is carbon-based. A carbon skeleton is the chain of carbon atoms that forms the “backbone,” or foundation, of any organic molecule. Because of carbon’s unique ability to form large, diverse and stable compounds, life would not be possible without carbon.
A covalent bond forms when two atoms share electrons or negatively charged sub-atomic particles. The number of covalent bonds any atom can form is related to the number of electrons in the outer shell.
Carbon has four electrons in its outer shell and can form four covalent bonds. This allows carbon to form large, diverse molecules.
There are four types of macromolecules, or large organic molecules, necessary for life to function: protein, lipids, carbohydrates and nucleic acids. All four macromolecules are based on a carbon skeleton.
When chains of carbon atoms are bonded to form a carbon skeleton, the types of chemical functional groups attached to that skeleton determine what kind of macromolecule will result.
Carbon is ubiquitous in nature. There are almost ten million known carbon compounds. Hydrocarbons (carbon and hydrogen chains) are the foundation of the fossil fuels coal, petroleum and natural gas. Carbon is found in carbon dioxide gas, diamonds, graphite and fullerines.