lipids 3.1.3 Flashcards
4 roles of lipids
source of energy
waterproofing
insulating
protection
what is triglyceride made out of
3 fatty acids and a glycerol
what bonds form between lipids and how are they formed
ester bond formed in a condensation reaction
what does the hydrolysis reaction of a triglyceride produce
3 fatty acids and glycerol (and 3 water molecules)
define saturated fatty acid
hydrogen carbon chain has no carbon-carbon double bonds
define mono saturated
single double bond in the HC chain
define polyunsaturated
multiple double bonds in the HC chain
4 properties of triglycerides
excellent source of energy
good storage molecule
large, non polar molecule
release water when oxidised
why are triglycerides excellent sources of energy
high ratio of energy storing carbon-hydrogen bonds to carbon atoms
why are triglycerides good storage molecules
low mass to energy ratio, much energy can be stored in a small volume
benefit of triglycerides being large, non polar molecules
insoluble in water, storage doesn’t affect osmosis in cells or the water potential in them
why do triglycerides release water when oxidised
high ratio of hydrogen to oxygen atoms
which type of lipid has polar molecules
phospholipids
which part of a phospholipid molecule is hydrophobic
fatty acids
which part of a phospholipid is hydrophilic
the phosphate molecule
what does being hydrophilic mean for the phosphate head
it interacts with water but not with fat
what does being hydrophobic mean for the fatty acid tail
orientates itself away from water but mixes readily with fat
what is useful about the hydrophilic phosphate heads
help to hold the surface of the cell surface membrane
what does the phospholipid structure allow them to do
form glycolipids by combining with carbohydrates within the cell surface membrane
what are glycolipids important in
cell recognition
why is it useful that phospholipids are polar molecules
forms a bilayer within cell surface membranes in aqueous environments
what is the test for lipids
1 take a completely dry and grease free test tube
2 to 2cm3 of sample, add 5cm3 of ethanol
3 shake test tube
4 add 5cm3 of water and shake
5 milky white emulsion indicates presence of a lipid
