Chemicals in Food

All living things need food. Food provides energy, the raw materials necessary for building and repairing the body, and food is also needed to control the chemical reactions in cells (meaning to control the metabolism). Food is made up of chemical components, which are made up of molecules, which are made up of atoms. There are four major types of molecules when mixed in different proportions create different types of food. Carbohydrates, Lipids, Proteins, and Vitamins are the four major types of molecules found in food.

Carbohydrates: there are three different types of carbohydrates that occur in nature.
1: Monosaccharides: these are more often named as simple sugars. Examples include fructose and glucose (found in fruit). They are called simple sugars because they consist of only one molecule, instead of groups of molecules joined together.
2: Disaccharides: these are a bit more complex than simple sugars (monosaccharides). Instead of one molecule, there are two molecules joined together. Examples are sucrose (cane sugar) and lactose (milk).
3: Polysaccharides: this consist of many molecules joined together. Examples are starch (bread) and cellulose (vegetables).
In respiration (see the 7 characteristics of life), carbohydrates break down and release energy, waste (carbon dioxide) and water. This type of reaction is called a catabolic reaction i.e. a complex molecule broken down into simpler molecules. The opposite, anabolic reaction, means a simple molecule built up into a complex molecule. Plants use this reaction to make their food.

Lipids: these are better known as fats and oils. Fats and oils are basically the same, except one is solid (fats e.g. butter) and the other one is liquid (oils e.g. sunflower oil). Lipids are important storage molecules. They provide insulation by depositing under the skin, and they protect the internal organs. Also, oils secreted from the skin help to waterproof the body.

Proteins: protein molecules are made up of sub-units called amino acids. These can be linked and they can form many different types of protein. Think of these amino acids as letters of the aphabet: when joined together, they form many different words. These amino acids are joined by what is called peptide links or bonds. Proteins can be found in muscle, hair, and nails. Enzymes, which are molecules who control chemical reactions in cells, are made from proteins. Hormones, which control and regulate body functions, are also made from proteins.

Vitamins: there are six different vitamins.
Vitamin A: these promote healthy eyes and eye sight and are mainly found in liver and carrots.
Vitamin B: there are eight sub sections of vitamins within this vitamin group, but they are all for mainly healthy skin and enhancing the immune and nervous systems. They can be found in pulses (beans, lentils), and meat such as liver and tuna.
Vitamin C: this is for good, healthy, strong connective tissue. It is mainly found in citrus fruits, but also in liver.
Vitamin D: this helps the absorption of calcium, which helps the bones and teeth grow. In a way, it indirectly helps the bones and teeth grow. It can be found in dairy products, but the skin also produces it when exposed to sunlight.
Vitamin E: these promote a healthy heart. They can be found in dairy products and in green leafy vegetables (e.g. spinach).
Vitamin K: this vitamin helps the blood to clot properly. It can be found in green leafy vegetables such as spinach, or cabbage.

Sources: New Senior Biology, Wikipedia,

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