Lipids Flashcards
Lipids contain
Carbon, hydrogen and oxygen
They contain less O than carbs but more H
First 3 functions of lipids
Energy source - triglycerides can be broken down and used in respiration to produce ATP
Energy store
Insulation- adipose tissue (composed of lipid) can be stored under skin. Effective heat insulator.
Last 2 functions of lipids
Buoyancy- lipids are less dense than water and so float on water
Protection- humans have a layer of fat around delicate organs to protect them
2 main types of lipid
Triglycerides
Phospholipids
Triglycerides are made of
1 molecule of glycerol and 3 fatty acids
Describe how a triglyceride is formed
One molecule of glycerol joins together with 3 fatty acids by water bonds in a condensation reaction.
Saturated fatty acids
No C=C double bonds in the hydrocarbon chain
High melting point
At room temp they are solid
Unsaturated fatty acids
Do have C=C double bonds in hydrocarbon chain
Low melting point
At room temp they are liquids as they can’t pack closely together
Phospholipids
Found in cell membranes
Plasma membrane made up of a phospholipid bilayer
Made of one glycerol, 2 fatty acids and one phosphate group
Polar and non polar parts of phospholipids
Polar hydrophilic head
Non polar hydrophobic tail
Polar definition
Electrons are not abated evenly so part of molecule is slightly positively charged and part of molecule is slightly negatively charged
Hydrophilic and hydrophobic
Hydrophilic- attracted to water
Hydrophobic- repels water
What do phospholipids form in water
Phospholipid bilayer
Describe how to test a sample for lipids
Add ethanol to sample
Add water
Shake and observe colour changes
Positive result: cloudy white emulsion
