Cell membranes

Cell membrane structure Phospholipid bilayer Glycerol-Hydrophilic; Fatty acid-Hydrophobic Fluid mosaic model  Lipid bilayer, Proteins, Carbohydrates, steroids

Reading quiz (pass HW, assignment sheet to center. You should also have WB __, 27 and lab report template (after WB 1). Put everything else under your desk so you are ready for the lab) 1. Diffusion involves the movement of molecules from areas of ____ concentration to ____ concentration 2. Which of the following best represents a concentration gradient? a.There is a uniform amount of perfume in the entire classroom b.There is more perfume in one area of the classroom than the rest of the classroom 3. Osmosis is the diffusion of the molecule ____ across a ______

Diffusion and osmosis Diffusion: Process of substances moving from higher concentration to lower concentration (does not require energy) Osmosis: Diffusion of water through a selectively permeable membrane Equilibrium: Dynamic state when rates of movement remain constant Tutorial

Reading quiz Match the following words with their meaning 1. Hypertonic 2. Hypotonic 3. Isotonic 4. Equilibrium a. state where movement occurs in both directions at the same rate b. Has a relatively lower concentration of solutes c. Has a relatively higher concentration of solutes d. Has the same concentration of solutes as the surrounding

Tonicity

Facilitative and active transport Passive: Small molecules  Alcohol, water, gases, small lipids Facilitated: Some larger molecules, protein needed to facilitate transport  Require energy?  No! High  low concentration

How do materials enter/leave the cell? Glucose will go through facilitated diffusion from higher to lower concentration What if glucose needs to be pumped out of the cell from lower to higher concentration Requires energy from ATP!

Endocytosis versus Exocytosis