lipids and cell membrane Flashcards
what do lipids consists of?
fatty acids
what are the two groups of lipids?
phospholipids and triglycerides
why can’t lipids form polymers?
as they do not have monomers as they have different base units instead
what are the types of lipids?
fats, seeds, oils and steroids
what are some properties of lipids?
- insoluble in water as fatty acids are hydrophobic and doesn’t affect water potential
- soluble in organic solution (ethanol)
- solidify at 20°C
what are lipids hydrolysed by?
lipase
what are some uses/function of lipids?
–> protection
- a layer to protect organs
–> insulation
- blubber (insulated from cold weather)
–> waterproofing
- plants, waxy cuticle
- animals, oils from sebaceous glands
–> energy source
- 1g of fat releases more than 1g of a carbohydrate
what are triglycerides made out of?
3 fatty acids and glycerol
how is a triglyceride formed?
- by a condensation reaction forming an ester bond between 3 fatty acids and glycerol
- 3 hydroxyl group from glycerol and hydroxyl group of each fatty acids
how many water molecules are lost during a condensation reaction to form a triglyceride?
3
what is the general formula for every fatty acid?
RCOOH
- R group (hydrocarbon chain)
- carboxyl group
what is a saturated fatty acid?
where the fatty acid only contains single carbon bonds
what is a unsaturated fatty acid?
- where the fatty acid only contains double carbon bonds
- so there are fewer hydrogen atoms
- causing the chain to bend
describe the method of the biochemical test for lipids
- crush up sample with pestle and mortar
- add water and ethanol
- shake for 2 mins
- pour into water
- If a positive result, should form a cloudy emulsion.
what are phospholipids made out of?
2 fatty acids + glycerol and a phosphate group
what are the properties of a phospholipid?
- they have a hydrophilic head (phosphate group)
- they have a hydrophobic tails (fatty acids)
how is a phospholipid formed?
- by a condensation reaction forming an ester bonds between 2 fatty acids + glycerol + phosphate group
- 2 hydroxyl group from glycerol and 2 hydroxyl group of each fatty acids and phosphate group
what is the cell membrane made out of and why?
phospholipids as it doesn’t allow polar molecules and ions through
what is a cell membrane?
it is partially permeable and controls the substances coming in and out the cell
what does the phospholipid form in a cell membrane?
bilayer and arranged in a fluid mosaic structure
what is a fluid mosaic structure?
where the phospholipids can still move with another neighbouring phospholipid but there are proteins that are scattered
what is a glycoprotein?
a carbohydrate that is attached to a protein
what is a glycolipid?
a carbohydrate that is attached to a lipid
what is the function of a glycoprotein and glycolipid?
acts as an receptor, antibodies and used for cell adhesion
what is the function of a peripheral protein?
acts as an receptor, which detects chemicals to be released for a response
what is cholestrol?
a type of lipid
what is the function of the cholestrol?
-provides stability which binds to the tails of the phospholipids
- regulates the fluidity of cell membrane
what is the function of the protein channel and channel?
allows larger molecules, polar molecules and ions through the cell membrane
what are the factors that affect cell membrane permeability?
temperature and solvents
how does temperature affect membrane permeability?
- by increasing the temp, the phospholipid have more ke, they move faster, so the membrane increases in permeability
- at high temp, proteins denature and the water in the cell expands increasing the pressure of the cell membrane which increases permeability
how does solvents affect membrane permeability?
- non polar solvents (alcohols+acetone) can insert themselves in bilayer
- can form hydrogen bonds near the ester bonds
- this pushes the phospholipids out of place
- this increases movement and increases permeability
OR - solvent denatures disrupting bonds moving phospholipids out of place
