Lipids
- Created by: jaaaz_v
- Created on: 09-11-15 18:40
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- Lipids
- Contain carbon, hydrogen and oxygen
- Form large molecules known as macromolecules
- Are commonly known as oils and fats
- Non-polar molecules
- Because the electrons in their outer shell are more evenly distributed than those in polar molecules
- Cannot dissolve in water because of this
- Glycerol
- Remains the same in all lipids
- 3 carbon atoms with 3 OH groups
- Fatty acids
- Carboxylic acid group (-COOH) at one end
- Main body is a hydrogen chain thats 2-20 carbons long)
- Can be saturated or unsaturated
- Fatty acids that cannot be artificially made are called essential fatty acids
- Saturation of fatty acids
- Unsaturated fatty acids have one or more double bond between the carbon atoms in the hydrocarbon chain
- Polyunsaturated - more than one double bond
- Monounsaturated - only one double bond
- Saturated fatty acids have no double bonds between the carbon atoms in the hydrocarbon chain
- The presence of C=c bonds cause the molecule to kink
- Molecules cannot pack closely together
- Are liquid at room temperature
- Unsaturated fatty acids have one or more double bond between the carbon atoms in the hydrocarbon chain
- Triglycerides
- Made up of one glycerol molecule and three fatty acid molecules
- Condensation reactions form ester bonds which link the glycerol to the fatty acids
- Process known as esterification
- 3 water molecules are lost forming these bonds
- Three water molecules must be supplied to break down the triglyceride
- Reverses the condensation reaction
- Examles of a hydrolysis reaction
- In the alcohol group
- Hydrogenation
- When double bonds are artificially brocken down and hydrogen atoms are artificially added
- Helps some oils/fats become solid at room temperature
- Phospholipids
- Composed of 2 fatty acids, 1 glycerol, and a phosphate group
- The phosphate ions contain extra electrons making them negatively charged
- So are soluble in water
- Have a non polar tail(fatty acid chains) and a polar head(phosphate group)
- Non polar tails are hydrophobic
- Polar heads are hydrophilic
- Act as surface action agents / sufactants
- Form bi-layer membranes
- Sterols
- Compex alcohol molecules based on a four carbon molecule ring structurewith a hydroxyl group at one end
- Cholesterol is a sterol
- Hydrophillic/hydrophobic nature allows it to sit inside cell membranes
- Influences the fluidity and strength of the membrane
- Emulsion test
- Used to identify lipids
- Mix the sample with ethanol; mix this solution with water and shake; if a white emulsion forms a layer on top then lipids are present
- Contain carbon, hydrogen and oxygen
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