BIOB10H3 Lecture Notes - Lecture 5: Exocytosis, Phagocytosis, Pinocytosis
25 Sep 2013
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Document Summary
Protein mobility: some freely mobile: others have restricted mobility, studied by frap: fluorescence recovery after photo- bleaching: can not identify individual protein units. You don"t know if the individual proteins are moving or they are attached to something else. Membrane lipid mobility: phospholipids are small and make up the bilayer. They don"t, instead seem to move freely within a compartment but movement is restricted between compartments. Removing membrane skeletal components removes some barriers to movement. Membrane domains & cell polarity: membranes are rarely homogenous. Movement across pm: plasma membrane: the plasma membrane has two main functions. Allow necessary materials in: charged and polar molecules can"t pass through hydrophobic membrane easily, membranes must be selectively permeable, two means of movement across pm: Passively by diffusion from high to low concentration [can involve protein channel] Actively by energy-coupled process : energy driven protein pump.
