[OLD] Biological Molecules - Lipids Flashcards
What do lipids consist of?
The molecules glycerol joined to three fatty acids
What is glycerol?
An alcohol
What are fatty acids?
long hydrocarbon chains with COOH on the end
How do fatty acids join to glycerol molecules?
By condensation reaction between OH groups on the glycerol and OH groups on the fatty acids.
What bonds join fatty acids and glycerol molecules?
Ester bonds
What are saturated fatty acids?
Fatty acids that have no double bonds between their carbons, and therefore are a straight chain
What are unsaturated fatty acids?
Fatty acids that contain double bonds between their carbons, and therefore have a bends in the their chain at each double bond
Why can’t unsaturated fatty acids pack close together?
The C-C double bonds create a bend in the chain at each one.
Where do unsaturated fatty acids tend to occur?
In plant oils e.g vegetable oil, olive oil, sunflower oil etc
Why are unsaturated fatty acids liquid?
Because they cannot pack closely together
What are saturated fatty acids bound together by?
Hydrogen bonds
What do saturated fatty acids’ straight chains allow them to do?
Pack closely together
Where are saturated fatty acids found?
Inn animal tissues e.g butter, lard etc
What do saturated fatty acids make?
Solid, saturated fats
Why do unsaturated fats have less C-H bonds?
They have C=C double bonds
Why are unsaturated fats healthier?
They have less C-H bonds, and it is the breaking of C-H bonds that can lead to energy release.
Therefore they have less energy in them when we break them down which makes them healthier in a calorie controlled diet.
5 uses of lipids
energy store metabolic water thermal insulation buoyancy shock protection
How are lipids used as an energy store?
They are insoluble in water and contain many C-H bonds that can be broken to release energy.
How are lipids used as metabolic water?
Aerobically respired fats release water e.g camel’s hump
How are lipids used as thermal insulation?
Deposited under skin to provide insulation e.g blubber in whales
How are lipids used as buoyancy?
Fat is less dense than water, therefore can provide buoyancy to whales etc
How are lipids used as shock protection?
Fat is deposited around some major organs to absorb shock e,g kidneys, heart
How do you get phospholipids from lipids?
Replace one fatty acid chain with a phosphate group
Where are phospholipids used?
In the phospholipid bilateral of cell membranes
3 uses of cholesterol
regulates fluidity of cell membranes
precursor for steroid hormones e.g oestrogen and testosterone
precursor for vitamin D
What does excess cholesterol cause?
Gall stones, atherosclerosis
