Ch. 4 Notes Parts One & Two

1. Ch. 4 NotesParts One & Two By: Brianna Shields October 13, 2005

2. DO NOW • 1. Identify the role of the golgi apparatus • 2. Describe the benefit that one large, central vacuole has for a plant cell • 3. What structure transports proteins from rough ER to the golgi apparatus?

3. Passive transport Concentration gradient Equilibrium Diffusion Osmosis Hypertonic solution Hypotonic Solution Isotonic Solution Ion Channel Carrier Protein Facilitated Diffusion Active Transport Sodium-Potassium Pump Endocytosis Exocytosis Receptor Protein Second Messenger VOCAB NOTEBOOK-list the terms in your vocab notebook, leaving about 3-4 spaces between each term

4. GOAL • To relate concentration gradients, diffusion and equilibrium • To predict the direction of water movement into and out of cells • T o describe the importance of ion channels in passive transport • To identify the role of carrier proteins in facilitated diffusion • To compare active and passive transport • To describe the importance of the sodium-potassium pump • To distinguish between endocytosis and exocytosis • To identify 3 ways that receptor proteins can change the activity of a cell

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6. Passive Transport Movement across the cell membrane No cellular energy required Random molecule motion from areas where substance is highly concentrated to areas where it is at low concentration Diffusion

8. Concentration Gradient A difference in concentration of a substance across a space Equilibrium- condition in which the concentration of a substance is equal throughout a space Diffusion

9. Equilibrium

10. Diffusion Materials will move until they reach equilibrium on both sides of the cell membrane Materials move randomly from high to low concentration, down concentration gradient Only occurs when membrane can be permeated Diffusion

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15. Osmosis 1. Diffusion of water through a selectively permeable membrane 2. Passive transport (no cellular energy) 3. Water moves down concentration gradient Osmosis

16. Osmosis 4. Water flows toward area with high concentration of dissolved particles and thus low concentration of free water molecules Osmosis

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19. Hypertonic Solution Cell shrinks because water flows out of cell into environment with more dissolved particles, fewer free water molecules Solutions

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24. Hypotonic Solution Cell swells because water moves in Fluid surrounding cell has less dissolved particles (more free water than cell’s interior) Can cause cell to burst Solutions

28. Cell bursting can be prevented by: 1. Rigid cell walls in plants and fungi 2. Contractile vacuoles in some unicellular eukaryotes 3. Animal cell mechanisms remove extra dissolved particles in cell Solutions

30. Isotonic Solution Dissolved particles and free water concentrations inside and outside of cell are equal Water diffuses in an out of cell at equal rates Cell doesn’t change in volume Solutions

36. What crosses the cell membrane? Usually only nonpolar molecules diffuse well through nonpolar lipid bilayer Highly selective transport protein channels let certain polar molecules to pass in or out of cell Crossing the Cell Membrane

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39. Drinking too much water can be just as bad as not drinking enough water. Can cause hyponatremia. This is because there’s not enough sodium (salt) in the cells. Drinking Gatorade can help. Real World Connection

40. Ion Channels 1. Nonpolar lipid bilayer prevents entrance of ions into cell 2. Allows important ionic substances to flow through into cell without contacting nonpolar membrane parts Crossing the Cell Membrane

41. Ion Channels 3. Some remain open, others gated 4. No energy needed 5. Materials move down their concentration gradient Crossing the Cell Membrane

45. Electrical charge and ion transport 1. Ion charge can determine how it moves across cell membrane 2. Inside of cell is usually negative 3. Positive ions tend to move into cell more readily (opposites attract) 4. Negative ions move out of cell (like charges repel) 5. Ion charge movement and concentration gradients can oppose one another Crossing the Cell Membrane

47. Facilitated Diffusion 1. Carrier proteins bind to & carry specific polar molecules across membranes 2. Movement occurs down concentration gradients 3. No energy required, passive 4. Carrier proteins shield substances from nonpolar interior of membrane Crossing the Cell Membrane

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