Transcript Passive Transport - (www.ramsey.k12.nj.us).

Transport
Passive Transport
• Passive transport: movement of molecules
across a membrane without energy
– Diffusion
– Osmosis
Diffusion
• Diffusion
– Movement of molecule from an area of high
concentration to low concentration
– Kinetic energy causes diffusion
– Diffusion requires no energy
Equilibrium
• Equilibrium
– When concentration (amount) of molecules of a
substance is the same throughout a space
Osmosis
• Osmosis
– Water molecules diffuse across a semipermiable membrane from an area of high
water concentration to lower water
concentration
• http://www.emc.maricopa.edu/faculty/farabee/BIOB
K/BioBooktransp.html
Movement of Water during Osmosis
• When the concentration of water molecules outside cell is
higher than concentration inside cell (hypotonic)
– H2O flows into cell
• When the concentration of water molecules outside cell is
lower than concentration inside cell (hypertonic)
– H2O flows out of cell
• When the concentration of water molecules is equal outside
& inside cell (isotonic)
– Equal movement of water
•
Blood cell osmosis
Active Transport
• Active Transport: molecules move across
a membrane from a low concentration to a
high concentration using energy
Active transport video
Endocytosis
• Cells take in molecules by putting a
membrane around them
Endocytosis & exocytosis
Exocytosis
• Molecules exit the cell by membrane
releasing contents out of cell