-1A: lipids Flashcards
what are the two kinds of lipids?
-triglycerides
-phospholipids
what do triglycerides and phospholipids have in common?
a molecule of glycerol
what does a phospholipid contain instead of the 3rd fatty acid tail?
a phosphate group
how are triglycerides formed?
-one molecule of glycerol + 3 fatty acids
-condensation reactions + removal of 3 molecules of water
-ester bonds formed
because triglycerides are formed via condensation reactions, what does this mean is released?
3 molecules of water
what are the properties of triglycerides?
-energy storage
-act as a metabolic water source
-doesn’t affect water potential + osmosis
-low mass
energy storage?
due to large ratio of energy storing carbon-hydrogen bonds compared to carbon atoms, lots of energy can be stored
metabolic water source?
-due to high ratio of hydrogen to oxygen atoms
-if triglycerides are oxidised (broken down) water is released, useful for animals that live in the desert e.g. camels
doesn’t affect water potential/osmosis?
large + hydrophobic molecules -> insoluble in water
low mass?
a large amount can be stored without increasing mass + preventing movement
what are fatty acids?
-R groups
-as number of carbons in fatty acid chain can vary = variable group
state and explain what are the two types of fatty acids
-saturated: hydrocarbon tail only has single bonds between carbons
-unsaturated: hydrocarbon tail consists of at least one double bond between carbons
properties of phospholipids?
-hydrophilic head
-polar
hydrophilic head (water loving)?
-attracts water due to negatively charged oxygen in phosphate group
-as phosphate group is charged + repels other fats
-fatty acid chains = hydrophobic tails to repel water + can mix with other fats
polar?
-due to two oppositely charged regions
-when placed in water, they position themselves so tails face inwards due to them being repelled from water + heads being exposed to water on the outside
-forms phospholipid bilayer membrane used in plasma membranes around cells
what is the test for lipids?
emulsion test
describe test for lipids
-dissolve/mix sample in ethanol
-add distilled water + shake
-positive result: white milky emulsion (more lipid, more noticeable colour should be)
the scientists expressed their results as percentage of lipid in plasma membrane by mass, explain how they would find these values
-divide mass of each lipid by total mass of all lipids
-multiply answer by 100
triglycerides have a hydrophobic tail, explain how this is important for their function
-hydrophobic tails force them to clump together in the cytoplasm as insoluble droplets
-means they can be stored in cells as a source of energy without affecting cells water potential
