BIOL130 Lecture : Biol130 - Unit6 Membranes Lecture Notes.pdf
11 Dec 2013
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Can"t pass through but respond to signal to perform fcn. Conversion of one energy form to another. Fluidity - how easily lipid molecules move within a membrane leaflet. Tightly packed tails - more viscous membrane, less fluid. Loosely packed - less viscous membrane, more fluid. Affected by length of fatty acids, degree of saturation (# of double bonds) Transition temperature - temp at which membrane gels (solidifies) At and above room temp - fluid. Below room temp - hydrophobic tails pack together and membrane gels. Must be at fluid state for normal cell function. Membrane phospholipids - amphipathic with polar head group and hydrophobic tail. Under warm temperature, the more cholesterol, the more viscous the membrane, less fluid. Can make up to 50% of plasma membrane lipid in some animal cells. Asymmetry of membrane lipids the percent of total membrane lipids is not evenly facing inner cell (cytosol) and outer cell (extracellular space)
