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Warm Up

Learn about the different ways substances move into and out of cells, including diffusion, osmosis, and active transport. Understand why cells need to be small for efficient molecular movement.

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Warm Up

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Presentation Transcript

  1. Warm Up • What are the 4 organic compounds? WRAP UP: What is larger, a sugar molecule? Or a starch molecule?

  2. Chapter 3 Section 2 The Cell in Its Environment

  3. Introduction • selectively permeable: some substances can pass through the cell membrane while others cannot (oxygen, food INTO CELL; waste OUT OF CELL)

  4. Substances moVe into and out of a cell three different ways… • Diffusion • Osmosis • Active Transport

  5. Diffusion • MAIN method by which small molecules move across the cell membrane • Molecules move from an area of HIGHER concentration to an area of LOWER concentration

  6. What Causes Diffusion? • Molecules are always moving and bump into one another • The more molecules, the more collisions • Collisions cause molecules to push away • And substance spreads out

  7. Osmosis • Diffusion of water molecules through a selectively permeable membrane • Water molecules move from highly concentrated area to a less concentrated area

  8. Passive Transport • Moving materials through a cell that do NOT need energy • Diffusion • Osmosis

  9. Active Transport • The movement of materials through a cell that requires the cell to use its own energy • Lower concentrated area to a higher concentrated area

  10. Two ways cell moves things by active transport… • Transport Proteins • Transport proteins in cell membrane “pick up” molecules outside the cell and carry them in • Calcium, Potassium, and Sodium • Transport by Engulfing • Cell membrane surrounds and engulfs a particle, forms a vacuole within the cell

  11. Why Are Cells Small? • As a cell gets larger, it takes longer for a molecule that has entered the cell to reach the middle of the cell

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