BIOL 121 Lecture Notes - Lecture 38: Surface 3, Peripheral Membrane Protein, Phospholipid
Document Summary
Cholesterol: found in the membranes of animal cells but not in those of plants or prokaryotes: act as membrane buffers: At high temperatures restrain the movement of lipids reducing the fluidity of the membrane. At lower temperatures disrupt fatty acids from associating by occupying space between lipid molecules, slowing the transition to the nonfluid gel state, increasing fluidity. Adjusting fatty acid composition: membranes have a mixed population of saturated and unsaturated fatty acids, fluidity is temperature dependent: At low temperature phospholipid pack & forms highly viscous semisolid gel: desaturases: Regulation of desaturases allows for organisms to regulate amount of unsaturated fatty acids and membrane fluidity. Bacteria, plants and animals use desaturase enzymes to alter their membrane fatty acids in response to their environment. Frye and edidin cell fusion experiment: add agents that cause mouse and human cell to fuse, lower temp to 0 c, add a fluorescently labelled antibody that recognizes the mouse h-2 protein in the plasma membrane.
