Chapter 1 - Diet and Nutrition

• Diet 


  A diet that contains all of the essential nutrients in the correct proportions to maintain good health
• Why do we need nutrients

  • To provide energy
  • To allow growth and repair
  • Fight diseases and keep our bodies healthy
• What is a Balanced Diet

  A Diet that includes 5 groups of substances in the correct amount

  They consist

  1. Carbohydrates
  2. Lipids
  3. Proteins
  4. Minerals
  5. Vitamins
• Macronutrients 


  Macronutrients -> Eaten in Large Quantities

  • Carbohydrates
  • Fats
  • Proteins
• Micronutrients 


  Micronutrients -> Eaten in Smaller Quantities

  • Vitamins
  • Minerals
• Types of Carbohydrates -> Their Roles

  -> Sugars and Starches

  Provide Short-Term Energy and Longer-Term energy storage

  -> Dietary Fibre

  Add bulk to faeces to prevent constipation
• Types of Lipids -> Their Roles

  -> Fats and Oils

  • Long-Term Energy Storage
  • Insulation
  • Cell Structure (Cell Membrane)
• Proteins -> Their Roles

  • Growth and Repair of Tissues
  • Enymes
• Vitamins and Minerals


  Essential for many processes

  
• How much energy do we need?

  -> Energy Consumed vs Energy Spent

  -> Depends on Age, Gender, Activity and Pregnancy

  Basal Metabolic Rate - Energy Requirements for different body functions

  Physical Activity Level - Energy Required for an activity
• What Chemicals make up Nutrients?

  Macromolecules ->

  Larger Molecules made of smaller subunits (Monomers)
• Carbohydrate Molecule 


  A Carbohydrate Molecule is called -> Monosaccharide

  glucose, fructose, galactose

  all have a formula of C6H12O6

  Monosaccharide + Monosaccharide = Disaccharide
• Lipids Molecule


  Carbon + Hydrogen + Oxygen = Lipids

  Composed of Glycorel and Fatty Acids
• Protein Molecules

  Carbon + Hydrogen + Oxygen + Nitrogen = Protein

  (Some contain Sulphur)

  >> Made of Subunits called amino acids

  >> There are 20 different amino acids
• Sequence of Amino Acids

  Determined by the gene that codes for it
• Amino Acids -> Proteins

  1. Folded, twisted, or joined up with other amino acid chains to form a functional protein
  2. The shape of a protein determines its functions and properties
• Testing for Starch

  Apparatus - iodine solution

  yellow/orange brown color

  1. Put some unknown solution into a test tube
  2. Add a few drops of iodine solution

  2.5 can be done on spotting tile

  3. The iodine solution will turn blue-black if starch is present
• Testing for Glucose


  An example of reducing sugars

  Benedict Solution >> Bright Blue in color

  1. Put some unknown solution into a test tube
  2. Add Benedicts Solution
  3. Heat the mixture in a water bath for 2-3 minutes
  4. Benedict solution turns red or orange in the presence of reducing sugars
• Testing for Protein


  Copper Sulphate + Sodium Hydroxide Solution = Biuret Reagent

  1. Put some unknown solution into a test tube
  2. Add a few drops of Biuret Reagent
  3. If any protein is present, the mixture will turn purple
• Testing for Lipids


  >> Fats and Oils do not dissolve in water

  <Emulsion Test>

  1. Put some unknown solution into a test tube
  2. Add ethanol and gently shake
  3. Add distilled water into another test tube
  4. Pour ethanol mixture into the water test tube
  5. Milky-white emulsion is formed with presence of lipid