Lipids Flashcards
What are the molecules that make up lipids and what does it lead to them being called?
1 glycerol
3 fatty acid
Known as triglycerides
Where do fatty acids join to glycerol?
OH groupsu
What is the general formula of glycerol?
C3H8O3
What elements do lipids contain?
Carbon
Hydrogen
Oxygen
What do fatty acids consist of?
- A carboxyl group COOH.
- a variable length hydrocarbon chain (CH2)n. There is always an even number of hydrogens between 14 and 22.
- a methyl group (CH3)
What is the general fatty acid formula?
CH3(CH2)nCOOH
Where can saturated fats generally be found?
In animals
Where can unsaturated generally be found?
Oils in plants
How is a saturated fat’s hydrocarbon chain structured?
Single bonds between carbons with all other bonds having hydrogen so it is ‘saturated’ with hydrogen.
What state is a saturated fat at room temperature and why?
Solid due to high melting point
What effect does high sat fat intake have?
Artheroma (fat) patches developing withing artery lining which can reduce/block blood flow or be taken in blood stream. Contributory factor in heart disease, strokes, etc
How are unsaturated fatty acids’ hydrocarbon chains different from sat?
One or more double bond.
What is the difference between mono and polyunsatured?
1 carbon-carbon double bond in mono.
2 or more in poly
What effect do the double bonds have?
Gives molecules a kink and they tend not to pack together well, giving a more open and therefore oily nature
What is unsaturated’s state at room temp?
Liquid
What are the bonds between glycerol and the fatty acids in a triglyceride called and how are they formed?
Three ester bonds formed by condensation reactions (releasing 3 water molecules).
What are the 2 key properties of Triglycerides?
Non-polar so don’t attract water (called hydrophobic molecules).
Insoluble in water (but soluble in some solvents e.g. Acetone and ethanol
What is the structural difference of a phospholipid?
One fatty acid is replaced by a phosphate group (PO4)3-
on the opposite site of the glycerol.
What is the effect of the phosphate group being ionised?
It is polar so it attracts water molecules, making the phosphate part of the phospholipid hydrophilic whereas the fatty acid tails are hydrophobic (repel water)
What is the phospholipids’ structure important in?
Formation of cell membranes
What is the test for Lipids/triglycerides?
Emulsion Test:-
- mix the ‘lipid’ with ethanol
- pour/decant mixture into water
- white emulsion shows that lipid is present. Stays clear= negative result
Use of lipids as an energy store:-
Store twice as much as same mass of carbohydrates- very efficient. However, can’t be broken down as quickly to be used in respiration so are only used for medium/long term storage.
What the 5 uses of lipids beyond as an energy store?
- thermal insulation
- protect vital organs like kidneys against physical damage
- provide buoyancy in aquatic animals
- provide water-proofing layers. e.g. waxy cuticles on leaves.
- provide metabolic water source from respiration in organisms in dry environments. E.g. Camels
