BIOLOGY 1P03 Lecture Notes - Lecture 5: Lipid Bilayer, Facilitated Diffusion, Cell Membrane
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28 Sep 2016
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Functions served by the plasma membrane: serves as a boundary, selective barrier, increases reaction efficiency. Nonpolar vs polar regions: hydrophobic fatty acid tails (water fearing, hydrophilic heads (water loving) Tail kinks in phospholipids increase membrane fluidity. View table 5-1 for different kinds of transport across membranes. Passive moving on their own (no energy required: this includes: simple diffusion, facilitated diffusion and osmosis. Energy requiring need energy: this includes: active transport, endocytosis, and exocystosis. Simple diffusion through the phospholipid bilayer. Facilitated diffusion through carrier proteins / channel proteins. Osmosis through aquaporin"s or the phospholipid bilayer: aquaporin"s allow water to go in large amounts or not go in. Hypotonic: lower solute concentration than that in the cell. Hypertonic: greater solute concentration than that in the cell. Isotonic: equal solute concentration compared to that in the cell. ** when water is plentiful, it fills the central vacuole, pushes the cytoplasm against the cell wall and helps maintain the cell"s shape.