BIOLOGY 2B03 Lecture Notes - Lecture 3: Cell Adhesion Molecule, Post-Translational Modification, White Blood Cell
5 Nov 2017
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Document Summary
Sensing the environment (receptors: encloses the cell, barrier between internal/external environment, growth and changes in cell shape, anchoring cytoskeletal structures, mediate cell/cell interactions. Fluid mosaic model of the cell membrane: the bilayer was considered to be uniform & fluid (lateral movement) Phospholipid components can modify fluidity: phosphoglycerides (phospholipids, short and largely unsaturated acyl chains that tend to kink and pack more loosely allowing rapid lateral movement (fluidity) Sphingolipids (phospholipids: long and largely saturate acyl chains allows tight packing (gel-like) Steroids (cholesterol: gives increased rigidity to membranes. Cholesterol favours phase separation: cholesterol interacts preferentially (but not exclusively) with sphingolipids, and favours phase separation between sphingolipids and glyceropholipids. Organization based on lipid shape: glycerophospholipids are roughly cylindrical. Sphingolipids and cholesterol are cone-shaped (fit together well) Functional rafts in cell membranes: a new aspect of cell membrane structure, based on the dynamic clustering of sphingolipids and cholesterol to form rafts that move within the fluid bilayer.
