Lipids Flashcards
What are lipids
- mixed group of hydrophobic compounds
- non polar
- composed of hydrogen, carbon and oxygen ( can contain phosphorus)
- much lower proportion of o2 compared to carbohydrates
- insoluble in water, souab,e in organic solvents
types of lipids
Triglycerides
Phospholipids
Waxes
Sterols- cholesterol
Structure of triglycerides
Contain an Ester bond , formed by esterification
Contains one glycerol and 3 fatty acids tails
Both types of molecule contain (oh) hydroxyl groups
The hydroxyl groups interact leading to the formation of 3 water molecules
What type of reaction is esterification
Condensation
Functions and roles of triglycerides
Thermal insulation to reduce heat loss
Cushioning to protect vital organs such as the heart and kidneys
Buoyancy for aquatic animals
Waterproofing
Why does the phospholipid bilayer not allow polar molecules through
As the phospholipid heads are polar the charged/polar molecules are repelled away from the cell
Describe the structure and properties of a phospholipid
Hydrophilic head - polar negatively charged, like water
Hydrophobic tail - not charged hates water
Why is the phospholipid bilayer fluid
The fluid mosaic model describes that the proteins float around in the membrane freely as they are not connected to the cell and can diffuse into the membrane
Chemical structure of glycerol
C3h8o3
3 hydrogens used in formation of 3 water molecules during esterification
Chemical structure of fatty acids
OH-C-(CH2)nCH3
CnH2nO2
Properties of saturated fatty acids
No more H atoms can be added, no double bonds
These are solid air room temp
Properties of unsaturated fats
More h could be added, double bond present
Liquid at room temp
Give an example of unsaturated fats
Triglycerides in plants
Often occur as oils
Healthy in the human diet
What are sterols
Complex alcohol molecules
4 carbon ring structure with a hydroxyl group
Hydroxyl group is polar therefore hydrophilic
Rest of the molecules is hydrophobic
What are triglycerides and phospholipids
macromolecules
Structure of triglycerides
1 glycerol , 3 fatty acids
Triglycerides being broken down
For the ester bond to be broken 3 water molecules need to be supplied
(Hydrolysis reaction)
Formation of triglycerides
Hydroxyl groups interact leading to the formation of 3 water molecules
(Condensation reaction)
Properties of phospholipids
Consist of a glycerol molecules, 2 fatty acids and a phosphate group, which is modified by an alcohol
Phosphate group is negatively charged (polar) , hydrophilic
Fatty acid chains are non polar , hydrophobic
Function of cholesterol in membranes
Hydrophobic and hydrophilic ends that interact with phospholipids providing rigidity
Why do some triglycerides not solidify at room temp
They are unsaturated
C are double bonded to h so more h could be added
Double bonds cause r groups to bend, reducing how compact they are
Lipids energy release compared to other molecules
Longer term storage of energy
Realise relatively more energy that carbohydrates or proteins
How may lipids from microorganisms be different
More unsaturated fats
Less overall lipids
Types of lipid containing glycerol
Triglyceride and phospholipid
Types of lipid containing only carbon hydrogen and oxygen
Fats waxes and sterols
Role of lipids
Membrane formstion, creation of hydrophobic barriers
Hormone production
Electrical insulation neccessary for impluse transmission
Waterproofing
Role of triglycerides
Thermal insulation fo reduce heat loss
Cushioning to protect vital organs
Buoyancy for aquatic animals
How salting preserves foods
Water leaves by osmosis
Microbes cannot survive / reproduce with lack of water
