LIFESCI 2 Lecture Notes - Lecture 3: Active Transport, Fluid Mosaic Model, Electrochemical Gradient
27 Aug 2016
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Document Summary
Organic molecules arrange themselves in ways that are meaningful to life. Integral proteins embedded in phospholipid transport, receptor, recognition, cell adhesion. Peripheral proteins attached to surface usually on the cytoplasmic side of the cell. Glycocalyx carbohydrate chains (sometimes coat) outside the cell (for cell recognition and membrane signaling) Diffusion moving down an electrochemical gradient. Selective permeability across the cell membrane (equilibrium doesn"t mean there"s no movement) Some substances can cross directly through phospholipids e. g. lipid soluble substances e. g. oxygen, carbon dioxide, steroids (not water very slowly only because it"s small) With the help of a specific molecule (protein) 1) ion channels na ion channel, potassium ion, calcium ion, chloride ion channel: aquaporins water. Can be gated open or closed depending voltage/chemical/mechanical processes changes between cell membrane e. g. mechanical hair cells in your ear bend to allow sound to trigger action potential.
