Lipids 3.1.3
- Created by: madii
- Created on: 22-09-17 17:31
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- Lipids
- like carbohydrates contain carbon, hydrogen and oxygen only but have a higher H:O ratio
- non-polar and cannot dissolve in water
- can dissolve in non-polar solvents such as alcohol
- Triglycerides
- formed when a glycerol molecule condenses, and combines, with three fatty acid molecules
- bonds between glyerol and fatty acids known as ester bonds
- glycerol has formula C3H8O3
- soluble in water due to polar OH groups
- different triglycerides formed depending on fatty acids
- Fatty acid is a long chain hydrocarbon attached to a carboxyl group
- saturated - no double bonds
- increase levels of cholesterol in blood and lead to atherosclerosis
- atherosclerosis is the narrowing of arteries due to build up of fatty deposits
- increase levels of cholesterol in blood and lead to atherosclerosis
- unsaturated - double bond, one is mono-unsaturated more is poly-unsaturated
- as humans we are capable of making some fatty acids but others we can't
- therefor it is essential we eat these within triglycerides and they are known as essential fatty acids
- Triglycerides
- formed when a glycerol molecule condenses, and combines, with three fatty acid molecules
- bonds between glyerol and fatty acids known as ester bonds
- glycerol has formula C3H8O3
- soluble in water due to polar OH groups
- different triglycerides formed depending on fatty acids
- Fatty acid is a long chain hydrocarbon attached to a carboxyl group
- saturated - no double bonds
- increase levels of cholesterol in blood and lead to atherosclerosis
- atherosclerosis is the narrowing of arteries due to build up of fatty deposits
- increase levels of cholesterol in blood and lead to atherosclerosis
- unsaturated - double bond, one is mono-unsaturated more is poly-unsaturated
- as humans we are capable of making some fatty acids but others we can't
- therefor it is essential we eat these within triglycerides and they are known as essential fatty acids
- therefor it is essential we eat these within triglycerides and they are known as essential fatty acids
- saturated - no double bonds
- formed when a glycerol molecule condenses, and combines, with three fatty acid molecules
- Triglycerides
- therefor it is essential we eat these within triglycerides and they are known as essential fatty acids
- saturated - no double bonds
- formed when a glycerol molecule condenses, and combines, with three fatty acid molecules
- Waxes
- lipid molecules which have single hydrocarbon chains linked to an alcohol other than glycerol
- not digested by animals
- waterproof coverings in living organisms
- insects chitin skeletons are covered in waxy layer
- prevent water loss and dehydration
- leaves have waxy cuticle
- prevent water loss and dehydration
- leaves have waxy cuticle
- insects chitin skeletons are covered in waxy layer
- Steroids
- lipids with highly , complex molecules, form basis of many hormones
- cholesterol is a well known steroid
- although it is thought as dangerous it is an essential molecule in living organisms
- found in cell membranes where it performs an integral structure role
- made in the liver and is also supplied in diet
- Phospholipids
- similar structure to triglyceride molecules
- however one fatty acid is replaced with a phosphoric acid molecule
- hydrophilic phosphate molecule contains OH groups which is attracted to polar water molecules
- rest of molecule is non-polar thus is hydrophobic
- therefor in water, phospholipids molecules automatically orientate themselves so fatty acid tail avoids water and phosphate heads are directed towards it
- hydrophilic phosphate molecule contains OH groups which is attracted to polar water molecules
- this maintains cell membrane structure as there are two layers of phospholipids(bilayer).
- orientation causes hydrophobic centre
- therefor in water, phospholipids molecules automatically orientate themselves so fatty acid tail avoids water and phosphate heads are directed towards it
- this maintains cell membrane structure as there are two layers of phospholipids(bilayer).
- orientation causes hydrophobic centre
- prevents free diffusion of water and other polar molecules through membrane, acting as a barrier of free movement
- orientation causes hydrophobic centre
- this maintains cell membrane structure as there are two layers of phospholipids(bilayer).
- prevents free diffusion of water and other polar molecules through membrane, acting as a barrier of free movement
- therefor in water, phospholipids molecules automatically orientate themselves so fatty acid tail avoids water and phosphate heads are directed towards it
- orientation causes hydrophobic centre
- therefor in water, phospholipids molecules automatically orientate themselves so fatty acid tail avoids water and phosphate heads are directed towards it
- however one fatty acid is replaced with a phosphoric acid molecule
- similar structure to triglyceride molecules
- Role of lipids
- High energy stores
- 1g of lipid can yield twice as much energy than 1g of carbohydrate or protein
- insoluble and stable, they can be readily respired to release energy, making ideal form of light energy store
- when respired, lipids release many water molecules (camels hump)
- insoluble and stable, they can be readily respired to release energy, making ideal form of light energy store
- 1g of lipid can yield twice as much energy than 1g of carbohydrate or protein
- Waterproof coverings
- lipids repel and are impermeable to water
- insects and leaves are covered in wax cuticles to prevent water loss
- sea birds preen feathers with oil produced from glands
- human skin glands produce sebum which prevents excessive drying of skin
- lipids repel and are impermeable to water
- insulating layers
- poor conductors of heat and so a layer under the skin allows animals to keep warm in cooler climates
- shock absorbing layers
- highly compressible and so a layer under skin prevents organs against damage
- additional lipid deposits often found around vital organs for an extra layer of protection
- High energy stores
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