Download Cell Membrane Selective Permeability

Cell Membrane
Cell Membrane
Selective Permeability
Cell membrane notes
Introduction
• Plasma (cell) membrane > thin barrier > controls traffic into and out of the cell
> basic method of transport in unicellular organisms
> selectively permeable
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Cell Membrane
STRUCTURE
• main macromolecules in membranes: > lipids & proteins, some carbohydrates
> Phospholipids:
– Hydrophobic­ fatty acid tails (sheltered from water) – the hydrophilic­ phosphate groups/ heads (interact with water)
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Cell Membrane
Membrane proteins help to regulate the movement of material in and out of the cell
Membrane proteins Transport: Act as channels to help move molecules through the membrane
Marker: Advertise the cell’s type
Receptor: Bind with specific substances
Enzyme: Assist chemical reactions
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Selective Permeability
• Cell membranes help decide what goes in and out of the cell
• This is known as selective permeability
• We say that cell membranes are “selectively permeable”
> Allows some things to go in and out of the cell but not other things
• Easier for small non­polar molecules
• Hard for polar and ionic molecules
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