1 8 14 Notes Membrane HW Quiz opens 4 PM Register your clickers for 1108 instructions posted on ELC this evening Today s Agenda The Importance of self testing Membrane structure and function Importance of Size o Use of models in biology o Using a model to study cell size o Relate back to biology For Monday Review evolution by natural selection and find examples of the importance of size in the world around you apply what you learned today Why membranes are important Increase surface area Keep things in and out MAKE LIFE POSSIBLE Membranes Separate internal from external environment Homeostasis ability to maintain a relatively stable internal environment more or less independent from the external environment Structures Functions o Phospholipids Barrier o Proteins Transport o Cholesterol o Extracellular matrix o Glycoproteins Cell Size Limited Eukaryotes 10 100 micrometers Prokaryotes 1 10 micrometers Why is cell size limited Nutrients can t reach the full volume of the cell if it s too large Models simplify question involves key variables Make model Test model 1 Rules 2 Back to nature test