BIO 121 Lecture Notes - Lecture 1: Integral, Sphingolipid, Close-Packing Of Equal Spheres
23 Nov 2020
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Document Summary
Covalently bonded amino acids, made by translation of mrna in the cytosol. Proteins fold spontaneously into the lowest energy form depending on the order of amino acids in the 1 sequence. Disulfide bridges typically form in membrane proteins and secreted proteins. Environment may dictate protein folding (cytosol vs membrane) Chaperones bind to parts of the protein, surround and provide an environment which will produce a folded protein stable enough that it won"t unfold after the chaperone is released. A selectively permeable membrane (non-polar core of the membrane) Small non-polar molecules diffuse easily (o2, co2, no) Small polar molecules diffuse but slowly (water) Large molecules cannot cross without transport proteins (aa"s, nucleotides, glucose) Phospholipid molecules spin on their axis and diffuse laterally. Rarely flip across the bilayer but flippases/scamblases (important for cell growth) Caused by cholesterol between phospholipids, also carbohydrates (glycocalyx) Caused by extra/intracellular proteins, transmembrane proteins have nubs on either end that stick out and are not symmetric.
