BIOL130 Lecture Notes - Lecture 9: Amphiphile, Phospholipid, Cytosol
20 Oct 2015
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Biol 130 lecture 9 unit 6 biological membranes. Membrane functions: have a selectively permeable barrier; transport mechanisms are needed for molecules that cannot pass through unaided, compartmentalization: a system for organizing cell reactions. Solute composition in the cell: the composition can be different inside and outside the cell, the cell can also create different compartments inside through membrane bound organelles. Membrane phospholipids: the polar head group defines the type of phospholipid and gives the fatty acid its name, all membrane lipids are amphipathic, the polar ends face the watery surface outside or within the cell. Membrane fluidity: tightly packed phospholipid tails =less fluid, freely moving tails (double bonds in fatty acid chains) = higher fluidity. Tonicity: hypotonic solution, more solute inside the cell than outside; net flow of water into the cell, animal cell: cell swells and possibly lyses, plant cell: cell swells, pushing on cell wall; gives plant stability.
