Chapter 3 Food ( Biomolecules) Summary Notes
After studying this chapter you should know the following:
1. Nutrition means getting and using food.

2. The Functions of food are
  1. for energy. ( e.g. sugars and lipids)
  2. for growth and repair. (e.g. protein).
  3. to control metabolic reactions (e.g. enzymes, hormones, minerals and vitamins).

3. Food is made of chemicals.
      • There are six common chemical elements in organisms: C, H, O, N, P and S,
      • five elements in dissolved salts: Na, Mg, Cl, K and Ca.
      • three trace elements: Fe, Cu and Zn. (trace elements are those needed in only tiny amounts)

4. Biomolecules are chemicals made in living organisms, e.g. glucose, lipids, proteins, DNA etc.
  The main biomolecules in food are Carbohydrates, Lipids, Proteins and Vitamins.
5.   Minerals come in to the body from the soil through plants and animals that feed on plants.
      Minerals are not classed as biomolecules.

Chemical elements combine in different ratios to form simple biomolecular units, (sub-units)e.g. the unit from which carbohydrates are made is Cx(H2O)y.

6. For each of the nutrients Carbohydrates, Lipids and Proteins you need to know the following:
  1. The elements it is made of.
  2. The sub-unit it is made of.
  3. Named examples of it.
  4. It’s general function.
  5. Two good sources of it in the diet.
  6. Its structural role. ( i.e. its role in building parts of cells and the body)
  7. Its metabolic role. (i.e. its role in reactions in the cells).
  8. A laboratory test for it.
See Tables below.

Once you know these facts for each biomolecule you should be able to make comparisons between them in terms of their similarities and differences.

7. Vitamins:
Vitamins are large complex organic molecules that are needed in relatively small amounts by the body for it to function properly.
Vitamins are classified as being either water-soluble or fat-soluble. This fact can be used...