3.1.3 Lipids Flashcards
What are the properties of lipids?
They’re a source of energy as when oxidised, they produce twice the amount of energy as carbohydrates with the same mass and produce valuable water
Insoluble in water but soluble in solvents such as alcohol and acetone- used for waterproofing
Slow conductors of heat- retain body heat, useful for insulation
Often stored around delicate organs for protection
What is the difference between fats and oils?
At room temperature fats are solid and oils are liquid
How are triglycerides formed?
By the condensation reaction of a molecule of glycerol and three molecules of fatty acid: OH of the glycerol joins with the H of the fatty acid
Why are triglycerides used in the body?
High ratio of energy storing carbon-hydrogen bonds to carbon atoms: release lots of energy
Low mass to energy ratio: good storage molecules
Large non-polar molecules: don’t affect water potential
Produce water when formed: valuable source of water
What does a condensation reaction between a glycerol and a fatty acid create?
An ester bond
Is the R group of a fatty acid saturated or unsaturated?
It can be either
What is a saturated molecule?
A molecule that has the maximum amount of hydrogen atoms bonded to it’s carbon atoms
What is a molecule called if it has one carbon to carbon bond?
Monounsaturated
What is a molecule called if it have more than one carbon to carbon bond?
Polyunsaturated
The more carbon to carbon bonds there are, the more ________ it is
Curved
What happens if there are no carbon to carbon bonds?
It is solid at room temperature because the triglycerides can stack on top of each other
If they can’t stack, the molecules can move and are called oils
What is the structure of a phospholipid?
It is a triglyceride molecules where one of the fatty acids is replaced by a phosphate head
The phosphate head is hydrophilic and doesn’t interact with fat
The fatty acid tail is hydrophobic and mixes readily with fat
See card
What is the emulsion test?
Add sample to a grease-free test tube
Add ethanol
Shake to dissolve any liquid
Add water and shake gently
A cloudy white substance indicates a lipid presence
The lipid is finely dispersed in the water to form an emulsion, light passing through the emulsion is refracted as it passes from oil droplets to water droplets, making it cloudy
What does a fatty acid look like?
See card
What is the structure of a glycerol molecule?
See card
