OCR AS Biology - Lipids

Biochemical Test
1. Ethanol Emulsion test
  1. Step 1-Mix the sample with ethanol
    1. This dissolves any lipid present
  2. Step 2- Pour the liquid into water in another clean test tube
  3. Step 3-If lipid is present a cloudy white emulsion will form near the top of the water
    1. The lipid comes out of solution and becomes dispersed as tiny droplets in the water
Types of Lipids
1. Triglyceride
  1. 1 Glycerol 3 Fatty Acids
    1. Joined by Condensation to form 3 covalent bonds
  2. Compact energy store insoluble in water so doesn't affect cell water potential
  3. Ester links
  4. Stored as fat
    1. Thermal insulation
    2. Protective purpose
2. Phospholipids
  1. 1 Glycerol 2 Fatty Acids 1 Phosphate Group
    1. Enter text here
  2. Phosphate group may have carbohydrate parts attatched
    1. Involved in Cell Signalling
  3. Molecule is part hydrophobic and part hydrophilic
    1. Ideal for cell membranes
3. Cholesterol
  1. Small,thin molecule that fits into the lipid bilayer giving strength and stability
  2. 4 Carbon based ring structures
  3. Steroid hormones
    1. Testosterone
    2. Oestrogen
Key Components
1. Glycerol
  1. Glycerol molecule always the same
  2. 3 Carbon molecule with three OH groups
2. Fatty Acids
  1. Molecule can differ significantly
  2. Have an acid group at one end
Functions
1. Energy Source
2. Steroid Hormones
3. Insulation
4. Component of Cell Membranes
5. Protection
6. Energy Store
Key Features
1. Release large amounts of energy when respired
2. Contains Carbon,Hydrogen and small amounts of oxygen
3. Different types of fatty acids
  1. C=C Unsatured
    1. Common in plants
    2. Cause fatty acid chains to push apart from other chains
    3. More C=C chains = oils
    4. More fluid
  2. C-C Satured
    1. Common in animals
    2. Called fats
    3. Less fluid
    4. Solid at room temperature
4. Insoluble in water
5. Less dense than water

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OCR AS Biology - Lipids

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	Creado por Chris Osmundse hace más de 10 años