Carbon, hydrogen, oxygen and nitrogen are the four most common elements found in living organisms. (CHON)
Carbon, hydrogen and oxygen are found in all the key organic molecules: proteins, carbohydrates, nucleic acids and lipids. Proteins and nucleic acids also contain nitrogen.
Any compound that does not contain carbon is said to be inorganic. A variety of inorganic substances are found in living things and are vital to both the structure and functioning of different organisms.
| Element | Example of Role in Plants | Example of Role in Animals |
|---|---|---|
| Calcium (Ca) | Co-factor in some enzyme reactions. | Important constituent of bones, needed for muscle contraction. |
| Iron (Fe) | A component of cytochrome pigments. | A component of hemoglobin and cytochrome pigments. |
| Phosphorus (P) | A component of ATP and DNA. | A component of ATP and DNA. |
| Sodium (Na) | Important in membranes, changes solute concentration and affects osmosis. | Important in membranes, changes solute concentration and affects osmosis, also important in transmission of nerve impulses. |
| Sulphur (S) | A component of amino acids. | A component of amino acids, needed to make some antibodies. |
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