2 13 12 Plasma Membrane Composed of 2 parallel sheets of phospholipids Polar heads are exposed to the interstitial fluid and the intracellular fluids with their non polar tails in the core Membrane proteins integral and peripheral cholesterol stabilizes the lipid bilayer of the plasma membrane Carbohydrates attached to the phospholipid heads form glycolipids Attached to the integral proteins to form glycoproteins Glycolipids and glycoproteins act as signal molecule on the surface of the cell A glycolipid glycoprotein rich area of the plasma membrane is called the glycocalyx makes the surface of the cell sticky and fuzzy The glycocalyx serves several functions on the surface of the cell The pattern arrangement of the carbs in the glycocalyx is unique for each cell type Changes in the glycocalyx is indicative of the cells turning cancerous A change in the pattern allows precancerous cells to evade the new cells The new cells can t recognize attack and destroy the cancerous cells The glycocalyx changes other cells don t realize it s a bad cell Membrane transport Passive or active Passive diffusion or filtration Diffusion simple facilitated or osmosis Active active transport of vesicular transport Vesicular transport exocytosis or endocytosis Endocytosis phagocytosis pinocystosis receptor mediated endocytosis Diffusion the movement of solutes down their concentration gradient Solutes move from areas of higher concentration to areas of lower solute concentration Simple diffusion lipid soluble hydrophobic solutes Cross the plasma membrane down their concentration gradient Ex Oxygen is carried by blood in blood vessels Oxygen is released in the capillaries located inside tissues Diffuses across the capillary wall into interstitial tissues
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