Lipids Flashcards
Definition of lipids
Lipids are macromolecules and all contain carbon, hydrogen and oxygen. They include Triglycerides, Phospholipids and Cholesterol.
Definition of Macromolecule
Its a very large, organic molecule
Describe lipids solubility
Lipids are insoluble in water because they are not polar therefore they don’t attract water molecules, but do dissolve in alcohol.
Definition of Triglycerides
They have one molecule of glycerol with three fatty acids attached to it.
How are Triglycerides synthesised?
They’re synthesised by the formation of an ester bond between each fatty acid and the glycerol molecule.
Definition of Glycerol
they have three carbon atoms. It is an alcohol, which means it has free -OH groups. There are 3 -OH groups.
What bonds and how many bonds do an Triglycerides have?
it has three ester bonds
How is each ester bond formed?
by a condensation reaction
Whats the process called in which Triglycerides are synthesised
esterification
Describe fatty acids
They have long ‘tails’ made of hydrocarbon. The tails are ‘hydrophobic’ therefore are insoluble in water.
Definition of saturated fatty acids
saturated fatty acids don’t have any double bond between their carbon atoms in their hydrocarbon tails. They fatty acid is ‘saturated’ with hydrogen.
Definition of unsaturated fatty acids
Unsaturated fatty acids have at least one double bond between carbon atoms, which causes chain to kink
Definition of phospholipid
molecule consisting of glycerol, two fatty acids and one phosphate group
Definition of cholesterol.
Cholesterol has a hydrocarbon ring structure attached to a hydrocarbon tail. the ring structure has a polar hydroxyl (OH) group attached to it.
What are the main two functions of Triglycerides
Energy source and energy store
explain Triglycerides been an energy source
its mainly used as energy storage molecules. Triglycerides can be broken down in respiration to release energy and generate ATP.
explain Triglycerides been an energy store
> Good for storage because the long hydrocarbon tails of the fatty acids contain lots of chemical energy - load of energy is released when they’re broken down. Because of these tails, lipid contain about twice as much energy per gram as carbohydrates.
They are insoluble in water, they can be stored without affecting the water potential of the cell.
Function of phospholipid
They make up phospholipid bilayer
Describe the phospholipid bilayer
Phospholipid head are hydrophilic and their tails are hydrophobic so they form a double layer with their heads facing out towards the water on either side.
Describe the centre of of the bilayer
The centre of the bilayer is hydrophobic, so water-soluble substances can’t easily pass through it - the membrane acts as a barrier to those substances.
Function of cholesterol
It help strengthen the cell membrane by interacting with the phospholipid bilayer.
Describe the structure of cholesterol and advantage of it.
Cholesterol has a small size and flattened - this allow cholesterol to fit in between the phospholipid molecules in the membrane. They bind to the hydrophobic tails of the phospholipid, causing them to pack more closely together. this helps to make the membrane less fluid and more rigid.
