Lipids

Lipids

Made up of carbon, hydrogen and oxygen. The portion of oxygen to carbon and hydrogen is smaller than in carbohydrates. They are soluble in water but soluble in orgainc solvents

Role of lipids:

• cell surface membrane
• sorce of energy- when oxidised lipids produce more than twice the amount of energy as the same mass of carbohydrates abd release valuable water
• water proofing- insoluble in water and good at conserving water. plants have waxy cuticles and mammals produce oily secretion from sebaceous glans
• insulation- fats are slow conductors of heat and are electrical insulators around myelin sheaths around nerve cells
• protection- are stored around delicate organs

Triglycerides

Made up of 3 fatty acids and a glycerol molecule. Each fatty acid forms an ecter bong with the glycerol molecule in a condensation reaction so water is release. ester bond can be broken in hydrolysis.

Difference in properties of triglycerides comes from difference in fatty acid chains. There are 70 different fatty acid chains that all have a carboxyl group attached.

• Single C-C bond= saturated chain (all carbon atomes are bnded with max number of H atoms)= straight chain= close packaging= solid at room temp(these lipids have high melting points and founf in warm blooded animals).
• Double C-C bond= unsaturated  chain= kink in straight chain= fatty acids unable to pack closely together= liquid at room temp(have low melting points and are found in cold blooded animals).

A double bond change the tertiary structure of the fatty acid so it turns into a liquid at room temp

Structure of triglycerides and properties

high ratio of energy storing c-h bonds to carbn atoms so are excellent store…