BIOC 302 Lecture Notes - Lecture 3: Membrane Lipids, Lipid Bilayer, Sterol
Document Summary
Steroid: lipids containing a core of 4 fused rings (3 with 6 carbons and 1 with 5 carbons) Amphipathic: waxes: esters of fatty acids linked to a long chain alcohol, eicosanoids, membranes. Membrane: sheet-like structure composed of lipids, usually only two molecules thick. As a result, membrane lipids tend to form bilayers (inner and outer leaflet) A pure lipid membrane is impermeable to large molecules (i. e. proteins and small charged and polar molecules) Combined with proteins, you can form (ex. plasma membrane + various organelle membranes) fluid mosaic model. Suggests a 2d fluid lipid bilayer with proteins floating in and on it. Lipids (and proteins) can diffuse laterally across a membrane, but rarely diffuse transversally or. Biological membranes only have the appropriate membrane fluidity for a given temperature range. Below this range, a phase transition occurs where the lipids are more ordered and the membrane becomes more semi-solid like or gel like.
