1A Lipids Flashcards
What are lipids?
Fats and oils
What do all lipids contain?
Hydrocarbons
Give two examples of lipids.
Triglycerides and Phospholipids
What is the structure of a triglyceride?
A molecule of GLYCEROL with 3 FATTY ACIDS attached with ESTER BONDS formed in CONDENSATION REACTIONS
Are fatty acid tails hydrophobic or hydrophilic?
Hydrophobic
Define hydrophobic.
Repels water
Define hydrophilic.
Has an affinity to water
What are the properties of triglycerides?
> Can act as ENERGY STORAGE MOLECULES - the HYDROCARBON TAILS release ENERGY when they are HYDROLYSED
The are INSOLUBLE (HYDROPHOBIC TAILS) so don’t affect WATER POTENTIAL
What is the structure of a fatty acid molecule?
> A CARBON atom at centre that links the fatty acid to GLYCEROL
Joined to a VARIABLE GROUP, HYDROXIDE GROUP and an OXYGEN atom
What is a saturated fatty acid?
DOES NOT contain any DOUBLE BONDS between CARBON ATOMS so forms a straight chain
What is an unsaturated fatty acid?
Contains DOUBLE BONDS so the chain KINKS
How are fatty acid chains formed?
CONDENSATION REACTIONS the form ESTER BONDS between the CARBONS of fatty acid molecules
Describe the structure of a phospholipid.
> A molecule of GLYCEROL with 2 FATTY ACID chains attached as well as a PHOSPHATE GROUP.
The glycerol and phosphate grouo form the head which is HYDROPHILIC and the fatty acid tail is HYDROPHOBIC
What are the properties of phospholipids?
> HYDROPHILLIC HEAD and HYDROPHOBIC TAILS allows them to form a double layer (suitable for structures like cell membranes)
Centre of the bilayer is HYDROPHOBIC so WATER SOLIBLE MOLECULES can’t pass through
Describe the emulsion test for lipids.
> Shake the sample with ETHANOL until it DISSOLVES then pour it into WATER
If lipids are present, the solution will form a MILKY-WHITE EMULSION
The GREATER the CONCENTRATION, the more noticable the ilky emulsion will be
