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Chapter 4 notes new

  1. 1. Chapter 4 Notes Cells and Their Environment
  2. 2. Molecules need to move across membranes in cells… Image modiified from: IN food carbohydrates sugars, proteins amino acids lipids salts, O 2 , H 2 O OUT waste ammonia salts CO 2 H 2 O products How does that happen?
  3. 3. I. Passive Transport <ul><li>Passive Transport -the movement of substances across the cell membrane without the use of energy by the cell. </li></ul><ul><li>There are many types of passive transport: </li></ul>
  4. 4. A. Diffusion <ul><li>Diffusion - is the movement of a substance from an area of high concentration to an area of low concentration. </li></ul><ul><li>Diffusion will eventually cause substances to be balanced (equilibrium) on both sides of the cell membrane . </li></ul><ul><ul><li>Ex: ink or food coloring moving through water. </li></ul></ul>
  5. 5. Diffusion-high to low concentration. Animatioin from:
  6. 6. B. Osmosis <ul><li>Osmosis - is the diffusion of water molecules across a selectively permeable membrane. ( Egg Experiment ) </li></ul>
  7. 8. <ul><li>1. Hypotonic -solute outside cell less than inside; water moves into cell; cell swells </li></ul><ul><li>2. Hypertonic- solute outside cell greater than inside; water moves out of cell; cell shrinks </li></ul><ul><li>3. Isotonic -solute outside cell equals inside; no net movement of water. </li></ul>
  8. 9. HYPOTONIC ISOTONIC HYPERTONIC solute outside ‹ inside Net movement of water into cell Animal cells: swell & burst = CYTOLYSIS Plant cells increase TURGOR PRESSURE solute outside = inside Net movement of water in and out of cell is equal No change in size solute outside > inside Net movement of water out of cell Animal cells: shrink = CRENATION Plant cells: can’t shrink due to cell wall Cell membrane pulls away from cell wall= PLASMOLYSIS
  9. 10. C.Facilitated Diffusion <ul><li>Facilitated Diffusion -when a membrane protein helps to transport a substance across a cell membrane. </li></ul>
  10. 11. Types of Facilitated Diffusion <ul><ul><li>1. Ion Channels -proteins that have a pore through which ions such as sodium, calcium, potassium can cross the cell membrane. </li></ul></ul>Animation from:
  11. 12. Types of FacilitatedDiffusion 2. Carrier protein -proteins that bind to specific substances, carry it across the cell membrane , and release it. Animation from:
  12. 13. II. Active Transport <ul><li>Active Transport-the movement of a substance into an area of higher concentration by using energ y from the cell in the form of ATP . </li></ul><ul><li>There are many types of active transport: </li></ul>
  13. 14. <ul><ul><li>1. Sodium-Potassium pump </li></ul></ul><ul><ul><ul><li>sodium ions are pumped out of the cell. </li></ul></ul></ul><ul><ul><ul><li>Potassium ions are pumped into the cell. </li></ul></ul></ul>
  14. 15. <ul><li>2. Endocytosis -substances that are too large to move into the cell membrane are moved by a vesicle that forms around it. </li></ul> / Animation from:
  15. 16. <ul><li>3. Exocytosis -substances that are too large to move out of the cell membrane are released by a vesicle that forms around it. </li></ul>
  16. 17. <ul><li>4. Membrane Receptor Proteins-proteins that help cell communicate with each other. </li></ul>