Food

• Nutrition is the way organisms obtain and use

  food.
• Autotrophic – organisms can

  make their own food

  E.g. plants and some bacteria
• Heterotrophic – organisms

  cannot make their own food.

  E.g. humans, dogs, badger.
• Herbivores – eat plants only. E.g. rabbit
• Carnivores – eat animals only. E.g. fox
• Omnivores – eat plants and animals. E.g. badger
• Nutrients are essential to maintain metabolism

  and continuity of life for all living things
• The functions of food:

  1. Provide energy.

  2. Provide raw materials for

  growth of new cells.

  3. Repair tissues.
• three groups depending on the amounts needed:

  Common Elements ( Macronutrient)

  Dissolved Salts ( Micronutrients)

  Trace Elements
• Common elements are those needed in large quantities
• The 4 most common elements are

  -Carbon  - C

  • Hydrogen  - H
  • Oxygen   - O
  • Nitrogen  - N
• Dissolved salts are elements required in smaller quantities.
• Most common dissolved salt elements are

  Sodium – Na

  • Potassium – K
  • Chlorine  - Cl
• Trace elements are those needed in very small amounts
• The main three trace elements are :

  • Iron – Fe
  • Copper – Cu
  • Zinc – Zn
• • The elements present in carbohydrates are:
  • Carbon, hydrogen and oxygen
• These elements are found in a fixed ratio$Cx(H2O)y$
• Carbohydrate Examples: Glucose has the formula C6H12O6
• Monosaccharides are made of a single sugar unit.

  • Examples: 

  Glucose - C6H12O6
• Disaccharides are made up of 2 monosaccharides joined together.

  • Examples - Sucrose = glucose + fructose
• Polysaccharides are large molecules made up of many monosaccharides joined together.
• Examples of Polysaccharides

  Cellulose – carbohydrate found in plant cell walls
• Sources of Carbohydrates

  • Bread
  • Pasta
  • Biscuits
  • Potatoes
• • Structural carbohydrates are used to build tissue. 

  Cellulose in plant cell walls
• Metabolic role of carbohydrates

  Aerobic Respiration - glucose is used to supply energy
• Lipids come in two main forms:

  Fats are solid at room temperature.

  E.g. butter and lard.
• Oils are liquid at room temperature.

  E.g. olive oil, sunflower oil.
• Lipids contain the elements

  Carbon

  Hydrogen

  Oxygen.
• Lipids

  The elements are not found in

  any fixed ratio.
• The basic unit of lipids is called a

  triglyceride.
• Each triglyceride is made up of one

  glycerol and 3 fatty acids.
• A phospholipid is a fat like

  substance where one of the fatty

  acids is replaced with a phosphate

  group.
• Sources of Lipids

  Butter

  Oils

  Red meat
• Structural role of lipids 


  Phospholipids form part of the

  structure of cell membranes
• Metabolic role of lipids

  Lipids are used in respiration to

  provide energy
• Proteins contain the elements

  Carbon

  Hydrogen

  Oxygen

  Nitrogen
• The basic unit of a protein is called

  an amino acid.
• Proteins are composed of long chains

  of amino acids.
• Shorter chains are called

  polypeptides
• Each amino acid is joined/bonded to

  each other by a peptide bond.