Lipids Flashcards
What do all lipids have in common?
They are not soluble in water ( hydrophobic ).
They are soluble in organic solvents such as ether or ethanol.
What are the main types of lipids?
Triglycerides (fats and oils), phospholipids (a major component of membranes), waxes and steroids (e.g. cholesterol).
What are triglycerides formed from?
Glycerol and 3 fatty acid molecules.
What are fatty acids?
Organic acids that form long hydrocarbon tails linked to a carboxylic group (COOH) at one end of the chain.
What happens in each triglyceride?
One glyceride molecule is joined together with three fatty acid molecules by three condensation reactions.
Where does the condensation reactions occur in triglycerides?
Between the OH groups of the glycerol and the carboxyl group of each fatty acid.
What are saturated fatty acids?
They contain the maximum number of hydrogen atoms, i.e. along the length of the hydrocarbon chain each carbon atom is linked with two hydrogen atoms.
What can vary in fatty acids?
The length of the hydrocarbon chain.
Whether the hydrocarbon chain has double bonds - a hydrocarbon with double bonds is described as unsaturated in comparison with chains with only single bonds that are saturated with hydrogen.
What does a double bond in a fatty acid do to the hydrocarbon?
The chain is not straight and has an angle at where the double bond is.
What bond is formed in a triglyceride?
Ester bond.
How is the boiling point affected of the hydrocarbon chain in triglycerides if the chain is saturated or unsaturated?
Triglycerides with unsaturated hydrocarbon chains (and shorter chains) tend to be liquid at room temperature - oils.
Triglycerides with saturated hydrocarbon chains (and longer chains) are solids - fats.
What are fats important in providing?
A thermal insulating layer in mammals, since they are poor heat conductors.
Buoyancy in marine mammals such as dolphins and whales.
A cushioning layer around and protection to internal organs such as the kidneys.
Water when respired - this is metabolic water, which is important for desert animals such as gerbils and camels.
What does a phospholipid consisting of?
A glycerol molecule, two fatty acid residues and a phosphate group.
How are phospholipids polar molecules?
The phosphate cause the glycerol end (head) to be polarised and soluble in water (hydrophilic or ‘water loving’). The long hydrocarbon chains (‘tails’) are non polar and insoluble in water (hydrophobic or water hating).
What is the reaction which joins each glycerol molecule with three fatty acid chains?
Condensation.
