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Cell Boundaries

Cell Boundaries. Fluid Mosaic Model . Cell Membrane. Regulates what enters and leaves the cell and provides protection and support. Made out of a phospholipid bilayer Gives its flexibility Also find protein embedded in the layer Which act as tunnels or pumps that help to move materials.

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Cell Boundaries

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  1. Cell Boundaries Fluid Mosaic Model

  2. Cell Membrane • Regulates what enters and leaves the cell and provides protection and support. • Made out of a phospholipid bilayer • Gives its flexibility • Also find protein embedded in the layer • Which act as tunnels or pumps that help to move materials. • Some have carbohydrates attach that act like chemical identification cards, allowing individual cells to identify one another

  3. What Is a Phospholipid? Each phospholipid is composed chemically of 2 fatty acids, a glycerol and a phosphate. Hydrophilic Hydrophobic

  4. Which component of a cell membrane contains a hydrophobic region and acts as a primary barrier to MOST foreign substances? Protein Cholesterol Carbohydrate Chain Phospholipid Bi-layer Inside of phospholipid bi-layer is hydrophobic ( the tails)

  5. Cell Walls • Lie outside the cell membrane • Are porous enough to allow water, oxygen, carbon dioxide and other substances through. • Main function is to provide support and protection for the cell.

  6. Membranes vs Walls

  7. Types of Cell Transport • Passive Transport - no cellular energy required to occur - goes with the concentration gradient - diffusion - facilitated diffusion - osmosis • Active Transport - requires cellular energy to occur - goes against the concentration gradient - Endocytosis/Exocytosis - Sodium Potassium Pump

  8. Concentration Gradient • The concentration gradient is the distribution of particles across space from high to low concentration

  9. Passive Transport • Energy for passive transport comes from the molecules themselves • In passive transport, molecules move with the concentration gradient - move from high concentration to low concentration

  10. Diffusion • Primary means of cell transport - molecules move from high to low concentration - movement continues with the gradient until the molecules are evenly distributed - equilibrium is achieved

  11. Facilitated Diffusion • Particles move with the concentration gradient across a transport protein in the membrane - ions, sugar and amino acids all move into and out of cells by facilitated diffusion

  12. Osmosis • The diffusion of water across a selectively permeable membrane - water moves from where there is more water to where there is less water - water moves toward higher conc. of dissolved material - solute

  13. Three osmotic environments • Hypotonic environment • Little(below) solute/lots of water What happens when you place cells in an environment that is hypotonic to it? Hmm Animal Cell Plant Cell

  14. Hypotonic Environment Animal Cell Plant Cell Before Water Moves In burst turgid

  15. 2nd type of Environment Hypertonic Lots of solute/little water What happens when you place a cell in an environment that is hypertonic to it? hmm

  16. 3rd Environment • Isotonic Environment • Equal amounts of solute and water What happens to a cell in an isotonic environment? hmm

  17. Isotonic Environment Animal Before Plant Water Moves In and Out at an equal rate No Change No Change

  18. Plasmolysis—loss of water due to osmosis Plasmolyzed Cells due to water loss

  19. Cytolysis Cytolysis: Cell Swelling from uptake of water This usually takes place when cells are placed in a hypotonic solution such as distilled water. Cytolysis Normal/Isotonic Plasmolyzed/Hypertonic

  20. Onion Cells and Osmosis Normal In Salt Water plasmolyzed

  21. Facilitated and Active Transport No ATP used for transport. Transport is greater to lesser like normal diffusion ATP is used. Transport is against a gradient, lesser to greater! Both utilize protein channels!

  22. Other Types of Transport

  23. Active Transport • Requires energy (ATP) because it goes from low concentration to high concentration. • Small molecules or ions across the membrane is carried out by transport protein and “pumps”. • Large molecules can cross the membrane by endocytosis and exocytosis.

  24. Sodium Potassium Pump • The protein “pumps” the sodium ion (Na+) out of the cell and potassium (K-) into the cell. • ATP provides the energy that keep the pumps working. • Is needed for the electrical impulse nerves

  25. Endocytosis Pinocytosis Endocytosis Requires Energy in the form of ATP In pinocytosis, liquid molecules are taken in as the membrane collapses to form a vesicle around the substance. http://highered.mcgraw-hill.com/olc/dl/120068/bio02.swf

  26. Endocytosis: Phagocytosis In phagocytosis, solid substances are taken in and a food vacuole forms around the substance.

  27. Exocytosis • Exocytosisthe cell releases • Large amounts of materials • From the cell.

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