Elaborate on lipids' role in plasma membranes
Key Terms
Describe the structure of a triglyceride
One molecule of glycerol with 3 fatty acids attached to it
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| Term | Definition |
|---|---|
Elaborate on lipids' role in plasma membranes | Phospholipids contribute to flexibility of membranes & transfer of lipid-soluble substances across them |
Elaborate on lipids' role in protection | Stored around delicate organs |
Elaborate on lipids' role in insulation | Fats = slow conductors of heat = help retain body heat |
Elaborate on lipids' role in waterproofing | Lipids are insoluble in water ∴ waterproof material In plants & insects: waxy cuticle to conserve water In mammals: produce oil secretion from sebaceous glands in skin |
Describe the structure of a triglyceride | One molecule of glycerol with 3 fatty acids attached to it |
What do fatty acids have? | Have long 'tails' made from hydrocarbons |
Properties in triglycerides differ due to variations in ___ __ | fatty acids |
Name 2 kinds of fatty acids | Saturated Unsaturated |
Draw a saturated fatty acid | |
Draw a unsaturated fatty acid | |
What does the double carbon bond causes the chain to do? | Causes it to kink |
Define mono-unsaturated | Single double bond |
Define polyunsaturated | More than one double bond |
Describe how a triglycerides forms | A fatty acid joins to a glycerol molecule When ester bond is formed = molecule of water is released - condensation reaction Process happens twice more = form a triglyceride |
Why are triglycerides good energy storage molecules? | Long hydrocarbon tails of fatty acids contains lots of chemical energy = lot of energy released when they're broken down ∴ contain twice as much energy per gram as carbohydrates |
Describe how the structure of a triglyceride makes them insouble | Triglycerides clump together as insoluble droplets in cells ∵ fatty acid tails = hydrophobic = tails face inwards = shielding themselves from water with their glycerol heads |
Where are phospholipids found? | In cell membranes |
Describe the structure of a phospholipid | One molecule of glycerol with 2 fatty acids + a phosphate group attached to it |
Draw glycerol | |
Draw the basic structure of a fatty acid | |
Draw a triglyceride | |
Phospholipids: | hydrophilic (attracts water) |
Phospholipids: Fatty acid tails is _______ | hydrophobic (repel water) |
Describe how phospholipids' structures relates to its function | Phospholipids make up the bilayer of cell membranes Heads are hydrophilic & tails are hydrophobic = form double layer with their heads facing out towards the water on either side Centre of bilayer = hydrophobic = water-soluble substances can't easily pass through Membrane acts as a barrier to those substances |
Describe the emulison test for lipids | Shake test substance with ethanol for few minutes so that it dissolves & then pour solution into water Any lipid will show up as a milky emulsion More lipid there is = more noticeable milky colour will be |