lipids Flashcards
(18 cards)
What are the elements contained in lipids?
Carbon, hydrogen and oxygen
Are lipids soluble in water?
No
What are the two types of lipids?
Triglycerides and phospholipids
What are triglycerides made of?
3 fatty acids and 1 glycerol
How are triglycerides joined together?
In a condensation reaction
What is the bond formed between a fatty acid and glycerol?
An ester bond
What are the two forms fatty acids can be in?
Saturated and unsaturated
How can lipids be hydrolysed?
Heating with acid or alkali, using the enzyme lipase at its optimum temperature or pH
Why do triglycerides have a high proportion of carbon to hydrogen bonds?
So they release twice as much energy as carbohydrates during aerobic respiration
Why do triglycerides have a high ratio of hydrogen to oxygen atoms?
Releasing water when respired (metabolic water) which is important for organisms in dry deserts
Why is it useful that triglycerides are insoluble in water?
They are ideal storage compounds as they are osmotically inactive
Where are triglycerides used?
On the waxy cuticle of insects and plants
What makes up a phospholipid?
A phosphate group, a glycerol and 2 fatty acids
What are the properties of a phospholipid’s head?
Polar and hydrophilic
What are the properties of a phospholipid’s tail?
Non-polar and hydrophobic
What structure do phospholipids form in a cell-surface membrane?
A bilayer
What is the test for lipids?
Emulsion test
What is the method for testing for lipids?
Place into a test tube with ethanol
Shake the mixture so that fat dissolves
Add this to water in another test tube and mix the contents
A white emulsion of fat droplets
