LIFESCI 2 Lecture Notes - Lecture 5: Sodium-Potassium Alloy, Blood Vessel, Lipid Bilayer

• School: UCLA
• Department: Life Sciences
• Course: LIFESCI 2
• Professor: Arnold, A.P., Esdin, J.

Document Summary

Fluid mosaic model if two cells are fused together, their membrane components mix over time. Acts as buffer by keeping membrane fluidity. Makes membranes more fluid at low temperatures, but makes it less fluid at physiological temperatures. * fatty acids don"t change composition when temperature changes, so at lower temperatures they become solid. double bonds produce kinks in fatty acids -> more fluidity (single bonds make them straight & rigid) Major components of membrane: protein & lipid. * rank in order of lease permeable to most permeable thru pure lipid bilayer: Sodium ions -> glucose (large uncharged) -> urea (small uncharged) -> oxygen (size matters more??) Polar & charged substances don"t diffuse across lipid portion of membrane. Used to transport molecules larger than ions or ions against gradient. E. g. epithelial cells of small intestine (handout) High glucose & low na+ inside cell, low glucose & high na+ outside cell.