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