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Cell Transport

Cell Transport. Homeostasis Cell Membrane Vocabulary Diffusion and Osmosis Active vs. Passive Transport. Homeostasis. Homeostasis means maintaining a balance internally despite what is going on externally.

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Cell Transport

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  1. Cell Transport Homeostasis Cell Membrane Vocabulary Diffusion and Osmosis Active vs. Passive Transport

  2. Homeostasis • Homeostasis means maintaining a balance internally despite what is going on externally. • Organisms must adjust to changes in the environment in order to survive or they could die!

  3. Homeostasis • For example, if it is below freezing outside, you must put on a heavy coat, gloves, double socks, a warm hat, ear muffs, and lots and lots of layers to maintain a healthy INTERNAL body temperature despite the EXTERNAL temperature

  4. Homeostasis • What structure maintains homeostasis in our cells? • How does it maintain homeostasis? • How? The Cell Membrane By controlling the passage of molecules, such as water, salts, food particles, etc in and out of the cell. (it regulates what enters and leaves) Through passive transport, active transport and cell to cell communication!

  5. The Cell Membrane Polar Head The Cell Membrane is: • A phospholipidbilayer • Two layers made of proteins and lipids Phospholipid Structure: • Polar Head (hydrophilic—”water loving”) • Nonpolar Tails—(hydrophobic—”water fearing”) Draw: Nonpolar Tails

  6. The Cell Membrane • Bilayer arrangement • Draw:

  7. The Cell Membrane • The proteins embedded in the cell membrane help it to function properly • 3 Types of Membrane Proteins • Transport—helps molecules enter or leave the cell • Marker—identify the cell • Receptor—allow cells to communicate

  8. The Cell Membrane Channel Protein Transport Proteins • Function as “gates/passageway” • Allow sugars, salts, etc to cross the membrane. • Special channel proteins: • Gated ion channels—gates that open/close • Carrier proteins—change shape to allow specific molecule to pass Carrier Protein http://personal.tmlp.com/Jimr57/textbook/chapter3/cms2.htm

  9. The Cell Membrane Marker Proteins • Cell’s “Name Tag” • Protein sticks out of phospholipid layer • Often has carbohydrates attached to outside end • Functions in cell identification to identify the cell to other cells and molecules • Important in • immunity—so various white blood cells in your body do not mistake your cells for foreign cells - blood typing – so you can’t receive just any ol’ type of blood

  10. The Cell Membrane Receptor Proteins • Function as “messenger/receiver” • Receive information from the environment (extracellular fluid, blood, interstitial fluid) and transmit that info to the inside of the cell • Protein has specific shape/charge to only allow certain molecules (like hormones) to bond • Triggers a response in cell http://personal.tmlp.com/Jimr57/textbook/chapter3/cms2.htm

  11. The Cell Membrane • Proteins are embedded/float-ing in the lipid bilayer.

  12. The Cell Membrane The Cell Membrane is: • Selectively permeable/semipermeable • permeable means to let objects travel through • so if it is selectively or semi permeable it only allows SOME things through and not others

  13. The Cell Membrane • This represents a selectively permeable membrane. • It allows (selects) certain things to pass through it. • Is the membrane permeable to ? • Is the membrane permeable to ?

  14. The Cell Membrane • Molecules pass through the cell membrane through: • Passive Transport • Diffusion • Facilitated Diffusion • Osmosis • Active Transport • Vesicles • Pumps

  15. Cell Transport Vocabulary • Molecule- the smallest unit of a compound/substance • Cannot be seen with the naked eye • 1 drop of water has 16,700,000,000,000,000,000,000 molecules of H20 • 1 grain of salt has 120,000,000,000,000,000 molecules of salt

  16. Cell Transport Vocabulary • Concentration Gradient- an area of high concentration next to an area of low concentration High Concentration of Molecules Low Concentration of Molecules

  17. Cell Transport Vocabulary • Equilibrium is when there is an EQUAL amount of molecules on each side of the membrane • There is no net movement meaning, there is continuous movement of molecules back and forth through the membrane.

  18. Passive Transport • Passive Transport is when molecules move from an area of HIGH concentration to an area of LOW concentration until equilibrium is reached. • Requires NO ENERGY! • Examples: • Diffusion • Osmosis • Facilitated Diffusion

  19. Passive Transport • Diffusion- the process by which molecules (“stuff”) spread from areas of high concentration, to areas of low concentration • Molecules are said to go “Down” or “with” the concentration gradient. • Requires no energy

  20. Where is the greatest concentration of cows? Where is the least concentration of cows? What will happen when the gate is opened?

  21. This process is called… diffusion

  22. Passive Transport • Facilitated Diffusion • What does facilitate mean? • When substances move from high to low concentration (down the concentration gradient) using channel/carrier proteins located in membrane • Does not require energy

  23. Passive Transport • A special type of diffusion is called osmosis • Osmosis- the process by which WATER molecules move from an area with a high concentration of water to an area of low concentration of water. • OR the “diffusion of water” • Requires no energy

  24. Passive Transport • In Osmosis water will move in where there is a low concentration of SOLVENT, and a high concentration of SOLUTE • A solute = “stuff” (salt, glucose, food particles) • A solvent = “water”

  25. Passive Transport • There are three ways water can move in a solution: • Hypotonic- water moves INTO a cell and the cell swells (gets bigger) • Hypertonic – water moves OUT of a cell and the cell shrinks (gets smaller) • Isotonic- water moves into AND out of a cell at an equal rate (remember- molecules are constantly moving)

  26. Passive Transport • Hypotonic- • Water moves into the cell (and could burst) • There is more solvent/less solute on the outside of the cell than the inside • So the solvent (water) moves to an area of low solvent (water) concentration

  27. Passive Transport • Hypertonic- • Water moves out of the cell (and will shrink) • There is less solvent/more solute on the outside of the cell than the outside • So the solvent (water) moves to an area of low solvent (water) concentration

  28. Passive Transport • Isotonic- water moves into and out of the cell at equal rates and stays the same size • So the concentration of solvent and solute on the inside of the cell is equal to the concentration of solvent and solute on the outside of the cell

  29. Practice • Draw arrows to show the flow of water • Label at the top if the solution is isotonic, hypotonic or hypertonic

  30. Where is the greatest concentration of solvent? Outside of the bag Which way does the water move? Into the Bag What type of solution is this? 100% distilled water Hypotonic selectively permeable membrane

  31. 90% water 10% salt Where is the greatest concentration of solvent? In the bag Which way does the water move? Out of the bag What type of solution is this? 80% distilled water Hypertonic selectively permeable membrane

  32. What happens to the bag? 90 % solvent 10% salt 80% distilled water selectively permeable membrane

  33. What happens to the bag? 90 % solvent 10% salt 80% distilled water selectively permeable membrane

  34. What happens to the bag? 90 % solvent 10% salt 80% distilled water selectively permeable membrane

  35. What happens to the bag? The bag shrinks. 90 % solvent 10% salt 80% distilled water selectively permeable membrane

  36. Passive Transport Recap! • Passive transport: • requires no energy • moves from high concentrations to low concentrations • Moves down the concentration gradient • Includes diffusion, facilitated diffusion and osmosis

  37. Active Transport • When molecules must move from a low concentration to a high concentration they must use active transport • Cells must transport certain amino acids, sugars, etc. into their cytoplasm from the surrounding fluid. • Some of these substances, however, are already in higher concentrations inside versus outside. • This requires energy!

  38. Active Transport • Opposite of Passive Transport • Molecules go against the concentration gradient • Energy is provided by the ATP made in the mitochondria • Active transport can involve pumps or vesicles • Requires energy

  39. Active Transport • Pumps allow molecules to travel against their concentration gradient • For example, the sodium/potassium pump actively transports sodium molecules and potassium molecules through the cell membrane • Requires energy

  40. Active Transport • Na+ pumped out of a cell • K+ pumped into a cell • Important because it prevents cells from bursting by lowering the sodium inside causing less water to enter through osmosis. • Requires energy

  41. Active Transport • Vesicles can transport molecules across the cell membrane through: • Endocytosis- moving INTO the cell • Exocytosis- moving OUT of the cell • Requires energy

  42. Active Transport • Exocytosis can help get rid of wastes or secrete products like hormones or insulin • Requires energy

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