Transport in the Cell Passive and Active Passive
- Slides: 20
Transport in the Cell Passive and Active
Passive Transport There are three types of passive transport 1. Simple Diffusion 2. Facilitated Diffusion 3. Osmosis
Simple Diffusion Movement of particles from an area of high concentration to an area of low concentration
Simple Diffusion Concentration gradient – difference in concentration between two areas
Simple Diffusion Doesn’t require any energy When diffusion ends, it is called Dynamic Equilibrium
Simple Diffusion Cell membranes are selectively permeable – only certain substances can pass through by diffusion
Simple Diffusion Water, oxygen and carbon dioxide pass through the membrane freely Ions (charged molecules) and large molecules can’t get through
Facilitated Diffusion Cell membranes of carrier proteins that help large charged molecules get through
Osmosis Net movement of water across a selectively permeable membrane
Osmosis Isotonic Solution – equal solute concentration No osmosis
Osmosis Hypertonic Solution – high concentration of solute Water moves out
Osmosis Hypotonic Solution – lower concentration of solute Water moves in
Who Cares? Hemolysis – bursting of the red blood cells Too much water in the cells can be fatal Crenation – shrinking of blood cells Too little water in the cells can also be fatal
Active Transport Movement of substances through a membrane against a concentration gradient
Sodium Potassium Pump Allows nerve and muscle cells to function. Requires energy to move sodium out and potassium in.
Bulk Transport Moves large quantities of materials across membrane Two types: Endocystosis Exocystosis
Endocystosis Bring materials IN A) phagocystosis – cell eating B) pinocytosis – cell drinking
Phagocytosis Pseudopods – fingerlike projections sent out by cell membrane that enclose particle
Phagocytosis Cell’s plasma membrane engulfs a drop of extracellular fluid
Exocytosis Take materials OUT (Exo = exit) Material is enclosed in a secretory vesicle, fuses with the membrane, and spills out