Lipids Phospholipids and sterols Flashcards
what is the difference between a fat and an oil?
-fat is solid at room temperature and is more saturated e.g butter
-oil is liquid at room temp and is less saturated.
why are fats described as macromolecules and not polymers?
-not made of repeating monomers like polymers but made of fatty acids and glycerol
what are the 3 most important groups of lipids?
-triglycerides
-phospholipids
-sterols
Lipids are mainly eaten in he form of triglycerides. what are the building blocks of triglycerides?
-glycerol
-3 fatty acids
Draw a structure of glycerol
Draw simple fatty acid
explain the difference between saturated and unsaturated fatty acids
saturated:
-straight chained
-solid at room temp
-no c=c double bonds
examples:
-palmitic acid
stearic acid
unsaturated:
-forms a kink/bend
-liquid at room temp
-c=c double bond
examples:
palmitoleic acid
-linoleic acid
draw a triglyceride formed
what bond is formed?
what is the bi product?
-ester bond
-condensation reaction, water formed
what are the functions of triglycerides in the body?
1.energy source - when carbohydrate levels are low, lipids are respired = twice as much energy as glucose
2.energy store - triglyceride is insoluble in water so can be stored without affecting water potential in adipose tissue
3.Insulation - in adipose tissue, lipids in nerve cells act an an electrical insulator, hibernation
4.Buoyancy - fat is less dense than water = float
5.Protection - fat around delicate organs e.g kidney to act as a shock absorber, peptidoglycan in bacteria, lipid capsule in bacteria.
how are phospholipids different to a triglyceride?
how are they similar?
-instead of 3 fatty acids phospholipids have two fatty acids and a phosphate head
-both have glycerol
what are phospholipids composed of and the structure?
hydrophobic tails facing inwards and hydrophilic phosphate head facing outwards.
what is the role of phospholipids in cells?
-forms bilayers - semi permeable
-forms micelles
-fluidity and stablity
what is an example of a sterol?
what is the structure?
-cholesterol
-four carbon based rings, small.
-carbon, oxygen, hydrogen
-hydroxyl group is hydrophilic but rest of molecule is hydrophobic
what are the functions of cholesterol?
-used in the liver to produce bile
-used in body to make vitamin D which is needed for proper development of bones
-regulate fluidity in biological membranes: inserts into membranes, the hydrophilic hydroxyl on the molecule can interact with the phosphate head of membrane and rest of molecule can interact with hydrophobic fatty acid tail of the membrane.
-production of steroid based hormones as they can pass through membranes and interact with receptors inside e.g testosterone.
how does structure of cholesterol help its function?
-can be integrated into biological membranes as it is small
-hydrophobic so can sit within the tail region of phospholipid bilayer
