All organisms need three basic macromolecules to grow: carbohydrates, lipids, and proteins.
Carbohydrates are biomolecules made of carbon, hydrogen, and oxygen. Carbohydrates are also known as saccharides, which include sugars, starch, and cellulose.
The simpler carbohydrates are the monosaccharides, such as glucose and fructose.
Image of glucose:
Carbohydrates are the main source of energy, which in animals such as the great white shark is accomplished through cellular respiration.
Proteins are chains of amino acids, compounds that have amino and carboxylate groups, as well as a side chain that is variable in length and composition.
The simpler aminoacid is glycine:
There are 21 amino acids used by animals to make proteins, and some can be synthesized by each organism, but others need to be consumed and are known as essential amino acids.
Proteins are used by organisms as a building block of cells and tissue, although they can also be used as a source of energy.
Lipids are nonpolar molecules that can have very different structures. Some examples of lipids are fatty acids, waxes, and sterols.
Fatty acids have a carboxylic acid united to an aliphatic chain, which is normally a chain of carbons and hydrogens. The simpler fatty acid is the formic acid:
Lipids have several functions: they are the basic component needed for cell membranes (phospholipids), they are used to store energy (long chain fatty acids), and they are needed to produce hormones such as estrogen and testosterone (sterols), among other functions.