3.1.3 Flashcards
Describe the properties of lipids.
Macromolecules containing C,H,O
Not polymers-no repeating monomers
Smaller proportion of carbon to oxygen and hydrogen than carbohydrates
Insoluble in water
Soluble in organic solvents eg alcohol
Lipids include fats,oils,steroids,sterols,waxes
What are the roles of lipids?
Flexibility of cell membranes
Energy source
Waterproofing
Insulation
Protection
Describe the structure of triglycerides
Most common lipid found in living organisms
Made up of 1 glycerol and 3 fatty acid molecules
R group of fatty acid can be saturated or unsaturated
Glycerol same in all lipids
R group varies
What is a saturated fatty acid?
Has no carbon carbon double bonds
Has most hydrogens possible, saturated with hydrogen
What is an unsaturated fatty acid and what are the types?
Has at least one carbon carbon double bond
Mono- one carbon carbon double bond
Poly- multiple carbon carbon double bonds
How are triglycerides formed?
The three -OH groups in glycerol allow it to join to 3 fatty acids
Condensation reaction
Forms an ester bond
How are triglycerides adapted to their functions?
Higher ratio of C-H bonds that store energy, therefore excellent source of energy
Low mass to energy ratio - lots of energy stored in a small volume
Large, non polar and insoluble in water - don’t affect water potential/osmosis
How are phospholipids formed?
2 fatty acids and a phosphate group bonded to a glycerol molecule
Where are phospholipids found?
Structural component of cell membranes
Which part of a phospholipid is hydrophilic and why?
Phosphate group is negatively charged and therefore attracted to polar water molecules
What part of a phospholipid is hydrophobic and why?
Fatty acid tail is insoluble in water and has a neutral charge
How are phospholipids arranged in water?
Form phospholipid bilayer
Hydrophilic head attracted to water due to negatively charged phosphate group attracted to positively charged hydrogen in water
Fatty acid tail hydrophobic as insoluble in water and neutral charge
Describe the biochemical test for lipids
The emulsion test
Add an alcohol eg ethanol to the sample
Add equal volume of distilled water
Shake
White emulsion = positive result
