BLG 311 Lecture Notes - Lecture 10: Halobacterium Salinarum, Membrane Lipids, Sphingomyelin
8 Feb 2018
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Internal membranes compartmentalize the eukaryotic cell and forms organelles. Key membrane functions: plasma membrane separates and maintains the living properties of the cell (defines it, maintains ion and chemical gradients, controls material exchange with the environment, senses and controls communication between cells ex. Rbcs must bend and flex through brain capillaries: acts as an impermeable barrier between the inside and outside of the cell, but also allows the (cid:272)ell to (cid:858)eat(cid:859) the e(cid:374)erg(cid:455) ri(cid:272)h (cid:373)ole(cid:272)ules fro(cid:373) the outside. Membrane bilayer: biological membranes are bilayers made of lipids (sandwich with hydrophobic portion facing the inside) and proteins; formed spontaneously. 3 of glycerol: overall structure is amphiphillic (has both hydrophilic and hydrophobic polarity, phosphatidylethanolamine, phosphatidylserine (negatively charged), phosphatidylcholine, sphingophospholipids: uses sphingosine for backbone with free oh group, sphingomyelin. Lateral diffusion: horizontal movement of phospholipids; likely or fast. Phospholipid movement in bilayer: transbilayer/flip flop diffusion: unlikely or slow, there are many different types of lipids in a lipid bilayer membrane.
