Lipids

Question 1

Describe how triglycerides form

Answer 1

● 1 glycerol molecule and 3 fatty acids
● 3 condensation reactions
● Removing 3 water molecules
● Forming 3 ester bonds

Question 2

What is a phospholipid

Answer 2

One molecule of glycerol, 2 fatty acids and one phosphate group

Question 3

what are the 2 groups of lipids

Answer 3

triglycerides, phospholipids

Question 4

what type of bond is formed between the condensation reaction of glycerol and a fatty acid [ RCOOH]

Answer 4

forms an ester bond

Question 5

the R group of a fatty acid may be what

Answer 5

unsaturated or saturated

Question 6

what is a saturated fatty acid

Answer 6

the hydrocarbon chain only has single bonds between carbonatoms

Question 7

what is a unsaturated fatty caid

Answer 7

the hydrocarbon chain consist of at least one double bond between carbon atoms

Question 8

Explain how the properties of triglycerides are related to their structure

Answer 8

Function: energy storage
● High ratio of C-H bonds to carbon atoms in hydrocarbon chain
○ So used in respiration to release more energy than the same mass of carbohydrates
● Hydrophobic / non-polar fatty acids so insoluble in water -clump together as droplets, tails inwards
○ So no effect on water potential of cell (or can be used for waterproofing)

Question 9

Describe how the properties of phospholipids relate to their structure

Answer 9

Function: form a bilayer in cell membrane, allowing diffusion of lipid-soluble (non-polar) or very small substances and restricting movement of water-soluble (polar) or larger substances

● Phosphate heads are hydrophilic
○ Attracted to water so point to water either side of membrane
● Fatty acid tails are hydrophobic
○ Repelled by water so point away from water / to interior of membrane

Question 10

Describe the emulsion test for lipids

Answer 10

-add ethanol and shake
-add water to solution
Lipid shows a milky emulsion