The Macro-nutrients
The macronutrients are the food type which we need in our diet in large quantities.
Carbohydrates
These chemicals include simple sugars like glucose and fructose. If the sugar is a single molecule it is a monosaccharide. If it consists of two sugars joined together then they are disaccharide's. There are more complex carbohydrates including starch, glycogen (animal starch) and cellulose. These are chains of sugars and are known as polysaccharides. They are primarily used for a source of energy but cellulose is a structural chemical.
Fats
These chemicals are made of three long fatty acid chains attached to one small glycerol molecule. If the fatty acids have one or more double bond in them then they are known as unsaturated fatty acids. They do not mix with water. They are used primarily for storing energy as they take up less space than complex carbohydrates. They are also used for insulation and to make membranes.
Proteins
These chemicals are complex chains of small subunits called amino acids. There are 22 different type of amino acid. By joining different amino acids in different combinations you get a different protein chain. The chain folds and coils up in a certain way, depending on the sequence of amino acids. A protein's 3 dimensional shape is very important for its function. Proteins have many different jobs. Some are important for making structural chemicals that give the cell its shape. Others are enzymes, which speed up and control the chemical reactions that go on in the cells. As proteins make up an important part of cells they are vital for growth.
