Biology 1202B Lecture Notes - Lecture 1: Passive Transport, Semipermeable Membrane, Electrochemical Gradient
15 Apr 2016
School
Department
Course
Professor
Document Summary
Structurally similar for all organelle membranes, functionally different due to proteins imbedded in the membrane. Membranes are composed of a selectively permeable phospholipid bilayer. Proteins embedded or attached to the membrane perform membrane functions. Fully saturated- bound to maximum number of hydrogen. Amphipathic molecules have a distinctly hydrophobic end as well as a hydrophilic end. Assembly of bilayer is spontaneous in an aqueous environment. Hydrophobic fatty acid chains minimize water contact by aligning in the core. Proteins embedded or bound to the membrane can also move laterally. Although fluid, cell structure is maintained by membrane protein attachment to cytoskeleton. Human and mouse cells grown separately in tissue culture. Human and mouse membrane proteins tagged with different dye molecule: human- red, mouse- green. Membrane fluidity influenced by fatty acid saturation and temperature. As temperature drops the random motion of lipids slows down: fluidity lost at a certain point.
