3.1.3 lipids

Question 1

what are the two groups of lipid?

Answer 1

phospholipids
triglycerides

Question 2

how are triglycerides formed?

Answer 2

the condensation reaction of one molecule of glycerol and three molecules of fatty acids

Question 3

what bond is formed in the condensation reaction between glycerol and a fatty acid?

Answer 3

ester

Question 4

what is the difference between an unsaturated fatty acid and a saturated fatty acid?

Answer 4

unsaturated = carbon-carbon double bonds
saturated = no carbon - carbon double bonds

Question 5

what differs phospholipids from tryiglycerides?

Answer 5

one of the fatty acids is replaced by a phosphate group

Question 6

how is the structure of triglycerides related to its function?

Answer 6

large molecules so energy can be stored in long hydrocarbon chains & wont affect water potential of the cell
low mass to energy ratio so they can store a lot of energy without gaining mass

Question 7

outline the structure of phospholipids

Answer 7

head of the molecule is hydrophilic and the tail is hydrophobic meaning that phospholipids are polar

Question 8

what is the function of a phospholipid?

Answer 8

important in cell surface membranes
they form a barrier
as the centre of the bilayer is hydrophobic water soluble substances can’t pass through easily

Question 9

outline the emulsion test for lipids

Answer 9

add ethanol to the sample
shake to mix
then add water
if lipids are present then a milky white emulsion forms
more lipid = more milky emulsion appears