topic 1 - lipids Flashcards
cgp (topic 1A) 6 - 7
what are triglycerides
a type of lipid that have one molecule of glycerol with three fatty acids attached to it
what are the long tails fatty acid have made of
hydrocarbons - the tails are hydrophobic therefore making lipids insoluble in water
what is the only thing that varies is fatty acids structure
hydrocarbon tail
how are triglycerides formed
by condensation reactions
what happens when an ester bond is formed
a molecule of water is released - a condensation reaction takes place
how many ester bonds are formed to form a triglyceride
three
how many kinds of fatty acids are there, what are they
two - saturated and unsaturated
what is the difference between saturated and unsaturated fatty acids
their hydrocarbon tails (R group)
a difference between saturated and unsaturated fatty acids
saturated - don’t have any double bonds between their carbon atoms, the fatty acid is ‘saturated’ with hydrogen
unsaturated - have at least one double bond between carbon atoms, causing the chain to kink
what are triglycerides similar to
phospholipids
what are the lipids found in cell membranes called
phospholipids
two differences between triglycerides and phospholipids
one of the fatty acids is replaced by a phosphate group
phosphate group is hydrophilic, whereas fatty acid tails are hydrophobic
how does the structure of triglycerides relate to its function
function: energy storage molecules
structure: long hydrocarbon tails - contain chemical energy - loads of energy is released when they’re broken down - due to these tails, lipids contain about twice as much energy per gram as carbohydrates
insoluble - so don’t affect water potential of the cell and cause water to enter the cell by osmosis - the triglycerides clump together as insoluble droplets in cells as the fatty acid tails are hydrophobic - the tails face inwards shielding themselves from water with their glycerol heads
how does the structure of phospholipids relate to its function
function: make up bilayer of cell membranes
structure: heads are hydrophilic and their tails are hydrophobic - so form a double layer with their heads facing out towards the water on either side
centre of bilayer is hydrophobic - so water substances can’t easily pass through it - membrane acts as a barrier to those substances
what test is used for lipids
emulsion test
