Transport Across Cell Membranes Flashcards
Fluid Mosaic model of membrane structure
Molecules within member and can move laterally (fluid) e.g. phospholipids
Mixture of phospholipids, proteins, glycoproteins and glycolipids
Phospholipid bilayer components
Hydrophilic phosphate heads - attracted to water (orientate to aqueous environment either side of membrane
Hydrophobic fatty acid tails - repel water (orientate to interior of membrane)
Embedded proteins (intrinsic or extrinsic)
Channel and carrier proteins (intrinsic)
Glycolipids
Glycoproteins
Glycolipid - (lipids with polysaccharide chain attached)
Glycoproteins - (proteins with polysaccharide chain attached)
Cholesterol
Binds to phospholipid hydrophobic fatty acid tails
Components of the cell membrane (4)
Phospholipid bilayer
Inverted proteins
Glycoproteins and glycolipids
Cholesterol
What does the fluid Mosaic model of membrane structure explain?
How molecules can enter and leave a cell
How does the phospholipid bilayer allow molecules to enter or leave a cell?
Allows simple diffusion of nonpolar small/lipid soluble molecules (e.g. water oxygen)
Restricts movement of larger/polar molecules
How do you channel proteins allow molecules to enter or leave a cell?
Allow movement of water soluble/polar molecules/ions down a concentration gradient (facilitated diffusion)
How do you carrier proteins allow molecules to enter or leave a cell?
Allow the movement of molecules against a concentration gradient using ATP (active transport)
Features of the plasma membrane that adapt for its other functions (4)
Phospholipid bilayer
Phospholipid bilayer is fluid
Surface proteins
Cholesterol
How does the cell membrane being a phospholipid bilayer adapt for another function?
Maintains a different environment on each side of the cell (compartmentalisation of the cell)
How does the phospholipid bilayer being fluid adapt it for another function?
Can bend into different shapes for phagocytosis/to form vesicles
How do the surface proteins (extrinsic glycoproteins/glycolipids) adapt the cell membrane for another function?
Cell recognition
Act as antigens/receptors
How does cholesterol adapt the phospholipid bilayer for another function?
Regulates fluidity
Increases stability