Lipids
Cards (13)
- LipidsHave large amounts of carbon and hydrogen and smaller amounts of oxygen
- Lipids
- Insoluble in water as they are non-polar, but can dissolve in alcohol
- Types of lipids
- Triglycerides
- Phospholipids
- Steroids
- TriglyceridesMade up of glycerol and fatty acids
- Glycerol
- 3 carbon atoms, has an alcohol, there's a free —OH group, important to structure of triglycerides
- Fatty acids
- Have a carboxyl group (—COOH) attached to a hydrocarbon tail, from 2-20 carbons long
- The carboxyl group ionises into a H⁺ and a -COO⁻ group, so it is an acid and can product free H⁺ ions
- Saturated fatty acidHas no C=C bonds
- Mono-saturated fatty acidHas 1 C=C bond
- Unsaturated fatty acidHas more than 1 C=C bond
- Triglyceride formation1. 1 glycerol bonded to 3 fatty acids, via a condensation reaction between —COOH group of the acid and —OH group of glycerol2. A covalent bond forms, called an ester bond
- Triglycerides
- An energy source- can be broken down in resp. to generate ATP
- Insulation- adipose tissue storage, electric and heat insulator
- Energy store- insoluble in water so store without affecting w.p.
- Buoyancy- fat is less dense than water so helps aquatic mammals keep afloat
- Protection- have fat around delicate organs to act as shock absorber
- Phospholipids
- Same structure as triglyceride but one fatty acid replaced with phosphate group
- Condensation reaction between an OH group on a phosphoric acid molecule and one of 3 -OH groups on glycerol form ester bond
- Phosphate group is negative so hydrophilic but fatty acids is positive so hydrophobic so phospholipid is amphipathic
- Cholesterol
- Steroid alcohol or sterol- a type of lipid which is not made from glycerol or fatty acids
- Consists of 4 carbon rings or isoprene units
- Small and hydrophobic
- Mainly made in liver in animals, plants have cholesterol derivative- stigmasterol
- Steroid hormones, testosterone and oestrogen and vitamin D are made from cholesterol