BIOL 1010 Chapter Notes - Chapter 3: Transmission Electron Microscopy, Cell Membrane, Electron Transport Chain
Document Summary
All raw materials, energy, and waste must cross plasma membrane to enter/leave cell. Magnifies about as much as tm: tm and sem = very expensive, not in student laboratory produce black and white images have to be colorized (might be indicated or not) Phospholipids: have polar (water-soluble) head, neutral nonpolar tails; 2 layers arranged so that nonpolar tails meet in center of membrane; 1 layer of polar heads faces watery sol"n outside cell, other faces watery sol"n of cytoplasm. Cholesterol: increases membrane"s mechanical strength; prevents it from becoming too rigid/flexible; prevents phospholipids form moving around too much, anchors proteins w/in membrane. Many proteins drift about bilayer for animals, plasma membrane described as fluid mosaic , constantly changing. Concentration gradient: concentration difference in different areas net ex: water/ions come this way channels constructed of proteins that span entire bilayer protein channel shapes/sizes & various amino acids" (that line channel) electrical charges determine which molecules can pass.
