What are the different types of lipids?
- Triglycerides
- Phosphlipids
- Cholesterol
- Steroid hormones
- Lipid-based hormones e.g. vitamiin A, E, D, K
What are the 3 catergories of lipids?
- Triglycerides
- Phospholipids
- Steroids
What is a surfactant and what do they do?
- It is short for surface active agents
- A substance that, when added to liquid, reduces its surface tension increasing its spreading and wetting properties
- An example of this is a detergent
- Lipids, particularly phospholipids, are a major component of pulmonary surfactant, a complex mixture that reduces surface tension in the lungs and aids in breathing.
What are the functions of triglycerides in living organisms?
- Source of energy => can be used in respiration to provide twice as much energy per gram than carbohydrates or proteins
- Energy storage => for the equivalent amount of energy, lipids have half the mass of carbohydrates and proteins which facilitates movment in animals and seed dispersal in plants. lipids are hydrophobic so not affect water potential meaning large amounts can be stored
- Buoyancy => lipids are less dense than water and aquatic animals have large amounts of subcutaneous fat
- Thermal insulation => bad conductor of heat, reducing heat loss.
- Protection => vital organs have fat pudding which cushions and absorbs impact
- Electrical insulaton => necessary for nerve impulse transmission. Lipids provide electrical insulation in the form of the myelin sheath around axons of nerve cells
- Reduces water loss
What are triglycerides formed of?
It formed from glycerol and 3 fatty acids through 3 condensation reactions
Draw glycerol
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Draw a fatty acid
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What is a saturated fatty acid?
- Every carbon in the hydrocarbon chain hs the maximum number of hydrogens
- All C-C bonds are single bonds
- They are solid at room temperature
What is the general formula of saturated fatty acids?
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What is the general formular for unsaturated fatty acids?
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What is an unsaturated fatty acid?
- They are C=C double bonds so fewer hydrogens in the hydrocarbon chain
- They are liquid at room temperature as the double bonds cause them to kink, preventing them from packing closely together
What is a polyunsaturated fatty acid?
It is an unsaturated acid with more than one C=C double bond
What is a phospholipid formed of?
- 2 fatty acids, 1 glycerol and a phosphate group
- They have a hydrophilic head and a hydrophobic tail
Draw a phospholipid
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Draw a triglyceride
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Where is cholesterol primarily manafactured?
In the liver and intestines
What molecules are manafactured using cholesterol?
- Steroid hormones (fat soluble) => lipid soluble hormones e.g. testosterone, cortisol, progesterone etc
- Fat soluble vitamins and vitamin D
- Bile
Draw cholesterol
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What is cholesterol’s contribution to the plasma membrane?
- Cholesterole is found in the phospholipid bilayer of the membrane
- It is positioned between the phospholipids with the hydroxyl group at the periphery (phosphate head) and the hydrophobic side bound to the fatty acid tails
- This adds stability to cell membranes and regulates the fluidity by keeping membranes fluid (hinders solidification) at low temperatures by disrupting the regular packaging of phospholipids
- It stops them from becoming too fluid at high temperatures
How do you test for lipids?
- Add ethanol to the sample and mix well
- Mix the resulting solution with water and shake gently
- If a white emulsion forms, this indicates the prescence of a lipid
