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Ch 4 PASSIVE AND ACTIVE TRANSPORT IN CELLS

Ch 4 PASSIVE AND ACTIVE TRANSPORT IN CELLS. Passive Transport. Movement across the cell membrane that does not require the cell’s energy. Concentration Gradient. A difference in concentration of a substance throughout a space. Equilibrium.

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Ch 4 PASSIVE AND ACTIVE TRANSPORT IN CELLS

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  1. Ch 4PASSIVE AND ACTIVE TRANSPORT IN CELLS

  2. Passive Transport • Movement across the cell membrane that does not require the cell’s energy

  3. Concentration Gradient • A difference in concentration of a substance throughout a space

  4. Equilibrium • Concentration of a substance is equal throughout a space

  5. Diffusion • Movement of a substance from an area of high concentration to an area of low concentration

  6. Selectively Permeable Membrane • Only allows some substances to pass through

  7. Draw this cell membrane

  8. oxygen, carbon dioxide, and other small, nonpolar molecules; some water molecules glucose and other large, polar, water-soluble molecules; ions (e.g., H+, Na+, K+, Ca++, Cl–); water molecules

  9. Diffusion Through Ion Channels • A transport protein with a polar pore that allows ions to diffuse into and out of the cell • The electrical charge of an ion can affect its ability to diffuse- The inside of a typical cell is negative, so it is more likely a positive ion will diffuse into the cell and a negative ion will diffuse out. • Opposites attract and like charges repel

  10. Carrier Proteins • Most cells have a different kind of protein that can bind to a specific substance on one side of the cell membrane and carry it to the other side

  11. Facilitated Diffusion • Carrier proteins are used to transport specific substances without using the cell’s energy

  12. OSMOSIS • Diffusion of water across a selectively permeable membrane • Hypertonic- water diffuses out of cell- cell shrinks • Hypotonic- water diffuses into cell- cell swells • Isotonic- water diffuses into and out of cells at equal rates

  13. 2% sucrose solution 1 liter of 10% sucrose solution 1 liter of 2% sucrose solution 1 liter of distilled water Hypotonic Conditions Hypertonic Conditions Isotonic Conditions

  14. VESICLES • Substances that are too large to be transported by carrier proteins, such as proteins and polysaccharides, are moved across the membrane by vesicles • Endocytosis- movement of a substance into a cell by a vesicle • Exocytosis- movement of a substance out of a cell by a vesicle

  15. ENDOCYTOSIS

  16. EXOCYTOSIS

  17. Active Transport • Movement of a substance across the cell membrane against the concentration gradient – against diffusion i.e. from low to high concentration • REQUIRES ENERGY from the cell supplied by ATP

  18. Receptor Proteins • Cells must also respond to important information and filter out unimportant information. To receive messages sent by signal molecules, cell membranes contain specialized proteins called receptor proteins that bind to the signal molecules allowing the cell to respond to the signal

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