Please enable JavaScript.
Coggle requires JavaScript to display documents.
1.3 lipids - Coggle Diagram
1.3 lipids
lesson 2: properties of triglycerides
fats at room temp in animals and liquid at room temp in plants
inter-molecular forces hold triglycerides together, triglycerides in animals tend to have saturated fatty acid tails and plants tend to have unsaturated fatty acid tails
saturated vs unsaturated fatty acids
unsaturated fatty acids contain carbon carbon double bonds which causes kinks in the fatty acid chain which means that the fatty acid tails are not as close together and the intermolecular forces between them are therefore weaker and less energy is required to break these inter-molecular forces so these triglycerides have lower melting points
contain ester bonds
roles of triglycerides
energy storage
insulation
protection of organs
water proofing
structure properties and function
lots of C-H bonds
high energy to mass volume ratio making it a good energy storage molecule
high ratio of hydrogen to oxygen atoms
means they release water when oxidised so provide and important source of water
large non-polar molecule
insoluble in water- storage of it does not affect water potential of the cell
emulsion test
grind up sample and place in test tube
add ethanol and shake
pour the ethanol into a test tube containing water
white emulsion will appear if lipids are present
lesson 3: phospholipids
structure of phospholipids
polar/hydrophilic head - water soluble, 'attracted to water', contains phosphate group and glycerol
non-polar/hydrophobic fatty acid tails - not soluble in water/lipid soluble, can be saturated or unsaturated
similarities & differences between triglycerides and phospholipids
similarities
lots of C-H bonds
both have fatty acid tales
both contain ester bonds
both contain glycerol
differences
phospholipids head contains phosphate groups
triglycerides have 3 fatty acid tails whereas phospholipids have 2
head of phospholipids is hydrophilic whereas all of triglycerides are hydrophobic
roles of phospholipids
main component of membranes
phospholipids form bilayers in water because the hyrophilic head points towards the water whereas the hydrophobic tails point away from the water
which molecules can diffuse through the phospholipid bilayer
non-polar molecules such as oxygen can diffuse across as they are lipid soluble so easily cross the cell membrane
large polar molecules such as starch cannot diffuse through the bilayer however smaller polar molecules such as H20 can diffuse through
lesson 1: fatty acids and triglycerides
lipids
consist of carbon, hydrogen and oxygen
large non-polar molecules, insoluble in water but soluble in organic liquids such as alcohol
not polymers but made of smaller molecules - 3 fatty acids and 1 glycerol
main groups or triglycerides and phospholipids
fatty acids
consist of a carboxyl group and an R group (variable hydrocarbon chain)
RCOOH
lesson 4: fluidity of the phospholipid bilayer
phospholipids with mostly unsaturated fatty acid tails
more carbon-carbon double bonds in the hydrocarbon chains
more kinks in the hydrocarbon chains
weaker inter-molecular forces
phospholipid bilyer/membrane is more fluid
why is it important for for membranes to be fluid
fluidity of membranes enables them to break and rejoin, this enables:
vesicles to be produced from the membrane in endocytosis
vesicles to fuse with membrane in exocytosis
fluidity also prevents the membrane breaking due to being too rigid
