Biology And Biomedical Sciences BIOL 2960 Lecture Notes - Lecture 4: Lipid Bilayer, Fluid Mosaic Model, Beta Barrel
12 Feb 2016
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Document Summary
Cell is separated from its environment by the plasma membrane. Biological membranes are comprised of a continuous phospholipid bilayer. Membranes regulate what enters and leaves a cell or cellular compartment. Physical organization and function of membrane depends on constituent lipids, proteins, carbohydrates. Lipid bilayers comprise major component of biological membranes: Bent tails pack less tightly in membrane -> increased fluidity. Via interaction with integral protein, head groups or through a lipid modification. Some integral membrane proteins are made up of beta sheets. Antiparallel beta sheets roll p to create a hollow cylinder or pore (aka a beta barrel). Hydrophilic r-groups in regions of protein exposed to aqueous environment. Fluid mosaic model: biological membranes are essentially two-dimensional solutions of lipids and globular proteins. Lipid bilayer functions as a solvent in which integral membrane proteins can diffuse laterally . Some proteins can also move horizontally in membrane. Hydrophobic molecules can diffuse across lipid bilayer readily.
