PHED-2506EL Lecture Notes - Lecture 3: Fluid Mosaic Model, Lipid Bilayer, Extracellular Fluid
14 Dec 2018
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Document Summary
Lecture 3: cells the living units part i. The cell is the smallest unit of life. All organisms are made of one or more cells. Plasma membrane: outer boundary of cell, selectively permeable membrane. Cytoplasm: intracellular fluid containing organelles, small strictures that perform specific functions. Barrier between what goes on in the cytoplasm and the cell"s immediate environment as follows: extracellular fluid: environmental side. Not a true barrier as it is selectively permeable. Structure and function: mechanical barrier, selectively permeable, electrochemical gradient, communication and cell signaling. Fluid mosaic model: double (bilayer) of lipids with imbedded proteins molecules (7-10 nm thin: bilayer forms the fabric of the membrane, consists of: phospholipids, cholesterol and glycolipids, phospholipids: hydrophobic and hydrophilic bi-poles, glycolipids: lipids bound with a carbohydrate. Cholesterol: immobilize the first few hydrocarbon groups of phospholipid molecules, makes bilayer less deformable and decreases its permeability to small water-soluble molecules: cholesterol prevents crystallization of hydrocarbons and phase shifts in the membrane providing membrane fluidity.
