BIOL 2021 Lecture Notes - Lecture 5: Lipid Bilayer, Hemoglobin, Hydrophile
Document Summary
Non polar: rhodopsin (absorb light) in mammalian retina. Rhodopsin associated with protein cascade of. Absorb light and making proton gradient (thus open the channel) In most transmembrane proteins, the polypeptide chain crosses the. Transmembrane polypeptide segment is mostly non-polar amino acids. In absence of water the polar peptide bonds form hydrogen bonds with one another. Hydrogen bonds are maximized in an a-helix. Can predict a transmembrane alpha-helix by the aa sequence: transmembrane proteins extend across the lipid bilayer, extend across the bilayer as a b-sheet (b-barrel) 3: some barrels form large channels. B-barrel proteins are abundant in the outer membrane of bacteria, mitochondria and chloroplasts. B-barrel proteins are more rigid than proteins comprised primarily (porins) of a helices. Some, but not all, b-barrel proteins are pore-forming proteins: porins are found in gram-negative bacteria and the outer membrane of mitochondria and chloroplasts. Gram stem , purple (crystal violet) stem gram positive.
