Membrane transport

This is a revision powerpoint for AQA AS Biology, topic: Membrane transport. Unit 1, chapter 3- cells and movement in and out of them

Ths powerpoint includes plasma membranes, diffusion, osmosis, active transport, absorption and cholera in depth detail.

I hope it is helpful, a lot of effort has been put into it :)

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AS Biology:
Membrane Transport…read more

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Lipids are non-polar compounds (charges are even in the
molecule) and are insoluble in water
· Triglycerides are a type of lipid made by joining a glycerol
molecule to 3 fatty acid molecules.
· Fatty acids are long hydrocarbon chains with a carboxyl (-
COOH) group at the end.
Test for lipids= Emulsion test
Ethanol and water turns cloudy due to the lipid in sample being finely dispersed in the water.
Lipids are non-polar, so they are soluble in organic substances (ethanol) and insoluble in aqueous (water)…read more

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Fatty acids
The property of a lipid depends on the fatty acid it contains.
Fatty acids vary in length and the number of double bonds they contain.
-A saturated fatty acid has only single bonds between carbon atoms
-Unsaturated fatty acids have at least one double bond
One double bond=monounsaturated
More than one double bond= polyunsaturated
Formation of triglycerides
Triglycerides are formed as a result of three condensation reactions between
the ­OH groups of glycerol and the ­COOH group of each fatty acid…read more

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Phospholipids have a similar structure to triglycerides but one of the fatty acids is replaced by
a phosphate group.
The lipid part of the molecule is non-polar and insoluble in water ­ hydrophobic.
The phosphate group is polar and water soluble ­ hydrophilic.
Phospholipid Monolayer Bilayered sheet Micelle…read more

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Fluid Mosaic Model…read more

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Extrinsic Intrinsic
- On the surface or - Span the whole width of
Phospholipids the bilayer
Allow lipid-soluble substances to enter - Give mechanical support - Some are carrier
and leave the cell to membrane or, in molecules for water-
conjunction with soluble material
Prevent water soluble substances from - Others are enzymes
glycolipids, as cell
entering and leaving the cell receptors for molecules
Make the membrane flexible such as hormones
· Provide structural support
· Act as carriers transporting water-soluble substances
across the membrane
· Allow active transport across the membrane by forming
ion channels for sodium, potassium, etc.
· Form recognition sites by identifying cells
· Help cells adhere together
· Act as receptors, e.g. for hormones…read more

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