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Part 1 What is an Isotonic Solution? • [Water] inside cell = [Water] outside cell • Cell is at equilibrium – Molecules are equally distributed in end • The amount of water entering the cell = the amount of water leaving the cell 95% water 95% water What is a hypotonic solution? • A solution that has MORE water, and LESS solute • The cell can lyse or burst if left in a hypotonic solution 100% water 95% water What is a hypertonic solution? • A solution that has LESS water and MORE solute • The cell will dehydrate 90% water 95% water Which direction does water flow? a) Water doesn’t flow at all. b) Water flows from an area of low concentration to an area of high concentration. c) Water flows from an area of high concentration to an area of low concentration. The plasma/cell membrane is selectively permeable ~only certain substances are allowed to pass through What can and can not pass through the membrane? CAN PASS THROUGH • Things that can dissolve in fat • Small molecules • Water CAN NOT PASS THROUGH 1. Things that can dissolve in water 2. Large molecules 3. Ions: Molecules with plus (+) or minus (-) charges CH2OH OH Part 2 There are three types… No energy is used [High] [Low] (it’s the natural flow) This means it goes down a concentration gradient 3 types of Passive Transport 1. Diffusion 2. Osmosis 3. Facilitated Diffusion Diffusion [High] [Low] Osmosis + CH2OH Facilitated Diffusion OH Passive Transport: Facilitated Diffusion There are three types… Energy is used [Low] [High] This means it goes up or against a concentration gradient 3 Examples of Active Transport 1. Protein pumps 2. Endocytosis 3. Exocytosis Protein Pumps Protein Pumps: proteins use energy to pull or pump materials into or out of the cell to stockpile or store substances the cell needs Different Types of Membrane Proteins (page 77) TRANSPORTERS RECEPTORS ENZYMES SIGNAL/ RECOGNITION Different Types of Membrane Proteins (page 77) signal/recognition Enzymes receptor transporter Endocytosis • • When cells engulf particles into the cell 2 types 1. Phagocytosis: When a cell wraps part of its membrane around a large particle forming a “pocket” or vesicle 2. Pinocytosis: The same process, but with smaller particles or liquids Exocytosis 1. A vesicle carrying a substance 2. fuses with the cell membrane 3. and releases the substance
