Biochemistry 2280A Chapter 11: Topic 6 - Textbook Notes - Chapter 11
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19 Jul 2016
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Biochemistry 2280 topic 6 lipids and membranes. Bilayer is self-sealing: tear exposes edge to water, which is energetically unfavourable, therefore, molecules rearrange spontaneously to fix it. Movement of phospholipids in bilayer: lateral diffusions is very common and rapid, flip-flop from one side to other is very rare, occurs only once a month without enzyme. Fatty acid tails not only flex but also rotate on long axis. New phospholipids made by enzymes bound to endoplasmic reticulum, using fatty acids as substrate. New phospholipids deposited only to cytosolic side of bilayer. Scramblases move random phospholipids from one half to other. Some of synthesized membrane stays in endoplasmic reticulum, rest taken to other organelles plasma membrane buds off of golgi apparatus. Certain phospholipids confined to one side of membrane. Flippases of golgi remove specific phospholipids from exterior to cytosolic half of membrane: asymmetry conserved when membrane transferred to plasma membrane, same orientation (cytosolic always cystolic)