Biochemistry of Lipids
Lipids
Macromolecules not polymers – different components joined together
Non-polar so insoluble on water and don’t affect water potential
3 important types:
Triglycerides Phospholipids Steroids
Functions of Lipids
Energy source – broken down into ATP during respiration
Energy storage – adipose cells store fat which doesn’t dissolve in water
Insulation – adipose tissue reduces heat loss
All biological membranes are made up of lipids
Protection – surface of plant leaves and delicate animal organs
Buoyancy – fat is less dense than water
Some hormones are lipids such as steroids
Glycerol
3 carbon (C) atoms and 3 hydroxyl (-OH) groups
Free hydroxyl group makes it an alcohol
Fatty Acids
Carboxyl group (-COOH) at one end attached to a hydro-carbon tail made of only
hydrogen and carbon
Anything from 2-20 carbons long (usually even)
Carboxyl group ionises into H+ and COO-
Is an acid since it produces a free H+ ion
Can be saturated (no double carbon bonds), monounsaturated (1 double carbon bond)
or polyunsaturated (2 or more double carbon bonds)
Double bonds make the chain kink so the lipids cannot stack and instead become fluid
making them oils not fats
More C=C bonds means less hydrogen atoms, more fluidity and a lower melting point
More unsaturated fats give a lower melting point
Triglycerides
Glycerol + 3 fatty acids bonded by ester bonds
Many different fatty acids
Many are made in our bodies, some must be ingested
Stored as fat, which has insulative, buoyant and protective properties
Lipids
Macromolecules not polymers – different components joined together
Non-polar so insoluble on water and don’t affect water potential
3 important types:
Triglycerides Phospholipids Steroids
Functions of Lipids
Energy source – broken down into ATP during respiration
Energy storage – adipose cells store fat which doesn’t dissolve in water
Insulation – adipose tissue reduces heat loss
All biological membranes are made up of lipids
Protection – surface of plant leaves and delicate animal organs
Buoyancy – fat is less dense than water
Some hormones are lipids such as steroids
Glycerol
3 carbon (C) atoms and 3 hydroxyl (-OH) groups
Free hydroxyl group makes it an alcohol
Fatty Acids
Carboxyl group (-COOH) at one end attached to a hydro-carbon tail made of only
hydrogen and carbon
Anything from 2-20 carbons long (usually even)
Carboxyl group ionises into H+ and COO-
Is an acid since it produces a free H+ ion
Can be saturated (no double carbon bonds), monounsaturated (1 double carbon bond)
or polyunsaturated (2 or more double carbon bonds)
Double bonds make the chain kink so the lipids cannot stack and instead become fluid
making them oils not fats
More C=C bonds means less hydrogen atoms, more fluidity and a lower melting point
More unsaturated fats give a lower melting point
Triglycerides
Glycerol + 3 fatty acids bonded by ester bonds
Many different fatty acids
Many are made in our bodies, some must be ingested
Stored as fat, which has insulative, buoyant and protective properties
