Lipids Flashcards
How are triglycerides formed?
Condensation of 1 glycerol molecule with 3 fatty acid chains, releasing 3 water molecules
What bond joins the glycerol to the fatty acids?
Ester bonds
What is the structure of fatty acids?
Long hydrocarbon tails (4-36 C)
Variable tail but most have 12-18 C
Glycerol links to central C on fatty acid
Can be saturated or unsaturated
What are the functions of triglycerides?
Chemical energy stored in fatty acid tail so lots released when broken down (2x more than in carbs)
Hydrophobic tails repel water, clump into insoluble droplets, no affect on water potential & osmosis
What is the structure of phospholipids?
Similar to triglycerides
One fatty acid is replaced by hydrophilic phosphate head
What are the properties of phospholipids?
Hydrophilic & hydrophobic regions so amphipathic molecule
Hydrophobic tails face away from water, hydrophilic heads face to water, creating phospholipid bilayer
What is the function of phospholipids?
Phospholipid bilayer makes up most of cell surface membrane, controls movement of substances in & out of cells
What is the structure of saturated fatty acids?
No double bonds between C, maximising H atoms
What is the function of saturated fatty acids?
Solid at room temp (chains pack closer), usually animal origin, increased risk of cardiovascular diseases, in dairy and fatty meats
What is the structure of unsaturated fatty acids?
At least one double bond between C atoms in the chain
What is the function of unsaturated fatty acids?
Liquid at room temp, double bond kinks chain so they can’t pack as tight, cooking oils
What are the 4 steps to test for a lipid?
Add 5cm3 of ethanol to sample
Shake & leave for 2-3 mins
Add distilled water to mixture
If lipid present, white, milky emulsion forms
