BRAINCAKETransport Across Cell Membranes
Revision notes for Transport Across Cell Membranes in AQA Biology (7401). Read the start of any lesson here, then sign in free for the whole lesson, the R.E.C.I.P.E. recall steps and the quiz.
- Plasma MembraneAll living cells are enclosed by a plasma membrane which is made of a phospholipid bilayer.
- PhospholipidsPhospholipids are made from a glycerol molecule joined to two fatty acid chains and a phosphate group.
- ProteinsMany proteins are embedded in the phospholipid bilayer.
- CholesterolCholesterol is a hydrophobic molecule that occurs within the membrane.
- GlycolipidsGlycolipids are made from phospholipids covalently bonded to a carbohydrate chain.
- GlycoproteinsGlycoproteins are proteins attached covalently to carbohydrate chains.
- Fluid-mosaic ModelThe arrangement of the components of the plasma membrane is known as the fluid mosaic model.
- Membrane PermeabilityThe plasma membrane is selectively permeable.
- Simple DiffusionDiffusion is the net movement of molecules or ions from a region of high concentration to a region of low concentration until evenly distributed.
- Facilitated DiffusionLike simple diffusion, facilitated diffusion is a passive process.
- Protein ChannelsChannel proteins form water-filled pores across the bilayer through which specific solutes can diffuse.
- Carrier ProteinsCarrier proteins are proteins that span the plasma membrane.
- Water Potentital ΦThe water potential Ψ is the pressure created by water molecules.
- OsmosisOsmosis is the passage of water from a region where it has a higher water potential to a region where it has a lower water potential through a…
- Osmosis in Animal CellsAnimal cells are enclosed in a cell membrane made of a phospholipid bilayer.
- Osmosis in Plant CellsPlant cells contain various solutes in the cytoplasm.
- Active TransportActive Transport is the movement of molecules or ions into or out of a cell from a region of lower concentration to a region of higher concentration…
- Sodium-Potassium PumpThe sodium-potassium pump is a carrier protein that actively transports sodium ions out of the cell and simultaneously transports potassium ions…
- Increasing the Rate of Movement across a MembraneThe rate of movement across a cell membrane by diffusion can be increased by increasing the surface area of the membrane, increasing the…
- Absorption in the IleumAbsorption of digested food occurs in the ileum of the small intestine.
- Co-transport in AbsorptionOn the membrane of the epithelial cell adjacent to the blood the sodium-potassium pump removes sodium from the epithelial cell lowering its…
- Oral Rehydration TherapyDiseases like typhoid or cholera infect the intestines and cause diarrhoea.