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Today’s Objectives. Students will be able to compare and contrast passive and active transport. Movement Thru Membrane. Cells use 2 methods to keep a Chemical homeostasis or maintaining a constant internal environment. Passive transport
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Today’s Objectives Students will be able to compare and contrast passive and active transport.
Movement Thru Membrane • Cells use 2 methods to keep a Chemical homeostasis or maintaining a constant internal environment. • Passive transport • Molecule movement occurs on its own without any energy input • Active transport • Cell expends energy to move molecules • ATP – adenosine triphosphate
(Simple) Diffusion • Diffusion • passive transport • Occur in a liquid; particles move high to low concentration • concentration gradient • High to low concentration • Leads to an even dispersal of particles
Membrane permeability • Semi-permeable membrane • partially permeable • Molecules and ions must pass thru channel proteins
Osmosis • Osmosis • passive transport • Diffusion of water • Driven by Osmotic pressure • Pressure exerted by dissolved particles in a solution
OSMOTIC PRESSURE • Isotonic solution • Osmotic pressure is the same on both sides of the membrane • Hypertonic solution • Cell is in a medium with HIGHER concentration of dissolved particles moves water OUT of the cell • Hypotonic solution • Cell is in a medium with LOWER concentration of dissolved particles moves water INTO the cell
Facilitated Diffusion • Facilitated diffusion • Passive transport • Carrier molecules move substances either into or out a cell increasing the rate of diffusion across the cell.
Movement of Larger Particles • Endocytosis • Process that moves particles into the cell • Exocytosis • Process that moves particles out of the cell • Both are forms or active transport
Movement of Larger Particles • Plasma membrane can engulf small particles • Pinocytosis -- “cell drinking” • Phagocytosis – “cell eating” • Both are forms of active transport
Questions to think about • Compare and contrast active versus passive transport. • Discuss diffusion and provide an example. • Your white blood cells attacking foreign bodies would be an example of what process of active or passive transport?