Warm up • The cell membrane is called phospholipid bilayer. – What is a phospholipid? – Which part of the phospholipid is hydrophobic? – Which part of the phospholipid is hydrophilic? – Define the term semi-permeable. – Quiz in 5 min. Notes: Passive Transport Ch. 5 Pg 97-102 Cell Transport • Molecules cross membrane in several ways – Some methods of transport require energy and some do not. – Depends molecules size, polarity, and concentration inside versus outside. Cell Transport • Small molecules and larger hydrophobic molecules move through bilayer easily. – e.g. O2, CO2, H2O Cell Transport • Ions, hydrophilic molecules, and large molecules do not move through the membrane on their own. – e.g. Na+, K+ Passive Transport • Movement across the membrane WITHOUT the use of energy Concentration Gradient • Molecules have kinetic energy • Concentration Gradient: difference between high and low concentration • Molecules move “down” gradient without energy • Equilibrium - when all molecules are evenly spread out • Draw this! Types of Passive Transport 1. Diffusion: Movement of molecules from high to low concentrations. Types of Passive Transport 2. Facilitated Diffusion: Molecules too big to move across the membrane use carrier proteins • Ex. Glucose Types of Passive Transport 3. Osmosis: diffusion of water across membrane • Water moves where there are more solutes. • Solute: What gets dissolved. • Solvent: What the Solute dissolves in. • Solution: The mixture of the solute and the solvent. Which way will the water move? Types of Tonicity 1. Hypotonic • More solutes inside the cell, water moves in • The cell swells Draw These Animal Cell Plant Cell Hypertonic • More solutes outside the cell, water moves out the cell • The cell shrinks Animal Cell Draw these! Plant Cell Isotonic • Equal solutes inside and outside • Water moves in and out at the same rate • Cell stays the same Draw These! Animal Cell http://www.youtube.com/watch?v=OYoaLz obQmk&index=2&list=PLexD8cl0p1Z8r4WyQXQ6R6-Hg81nERSg Plant Cell