Energy

The concept of energy is typically fundamental. The total source of energy comes from the sun. Energy can be defined as the ability or capacity to do work. It cannot be either created or destroyed. For example, to walk up a flight of stairs requires energy. In order for a person to walk up a flight of stairs, the energy used comes from some food source. Food contains potential energy that can be accumulated for …

…organisms. When glucose, a monosaccharide, is oxidized, the bond energy of the glucose molecule is converted into the chemical energy of adenosine triphosphate (ATP) molecules. Fortunately, this energy can be converted into bond energy in some cellular components, for example, carbohydrates, fats, or proteins. It can also be converted to mechanical energy, as an organism becomes mobile. Moreover, before an organism as a whole can expend energy, the basic units of life, cells, require energy.