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Diffusion and Osmosis

Diffusion and Osmosis. KEY CONCEPT Materials move across membranes because of concentration differences. Passive transport does not require energy input from a cell. Molecules can move across the cell membrane through passive transport. There are two types of passive transport. diffusion.

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Diffusion and Osmosis

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  1. Diffusion and Osmosis

  2. KEY CONCEPT Materials move across membranes because of concentration differences.

  3. Passive transport does not require energy input from a cell. • Molecules can move across the cell membrane through passive transport. • There are two types of passive transport. • diffusion • osmosis

  4. 3.4 Diffusion and Osmosis Diffusion and osmosis are types of passive transport. • Molecules diffuse down a concentration gradient.

  5. Diffusion and osmosis are types of passive transport. • Osmosis is the diffusion of water molecules across a semipermeable membrane.

  6. Diffusion and osmosis are types of passive transport. • There are three types of solutions. • isotonic • hypertonic • hypotonic

  7. Some molecules can only diffuse through transport proteins. • Some molecules cannot easily diffuse across the cell membrane. • Facilitated diffusion is diffusion through transport proteins.

  8. Biology textbook video • C:\Program Files\McDougal Littell\Power Presentations-Biology\START Power Presentations.html

  9. 3.5 Active Transport, Endocytosis, and Exocytosis KEY CONCEPT Cells use energy to transport materials that cannot diffuse across a membrane.

  10. Active transport requires energy input from a cell and enables a cell to move a substance against its concentration gradient. • Passive transport requires no energy from the cell. • Active transport is powered by chemical energy (ATP). • Active transport occurs through transport protein pumps. • Cells use active transport to maintain homeostasis.

  11. A cell can import and export large materials or large amounts of material in vesicles during the processes of endocytosis and exocytosis. • Cells use energy to transport material in vesicles. • Endocytosis is the process of taking material into the cell. • Phagocytosis is a type of endocytosis.

  12. A cell can import and export large materials or large amounts of material in vesicles during the processes of endocytosis and exocytosis. • Cells use energy to transport material in vesicles. • Exocytosis is the process of expelling material from the cell.

  13. Biology textbook presentation • C:\Program Files\McDougal Littell\Power Presentations-Biology\START Power Presentations.html • United streaming: http://player.discoveryeducation.com/index.cfm?guidAssetId=EE86FD99-F075-49FD-BBDC-61DE73CA949F&blnFromSearch=1&productcode=US

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