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Cell Boundaries

7-3. Cell Boundaries. Cell Membrane. Cell membrane = controls what enters and leaves the cell provides protection and support Receives chemical signals All cell membranes are made up of a double layer known as a lipid bilayer. Outside of cell. Carbohydrate chains. Proteins. Cell

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Cell Boundaries

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  1. 7-3 Cell Boundaries

  2. Cell Membrane • Cell membrane = • controls what enters and leaves the cell • provides protection and support • Receives chemical signals • All cell membranes are made up of a double layer known as a lipid bilayer.

  3. Outside of cell Carbohydrate chains Proteins Cell membrane Inside of cell (cytoplasm) Protein channel Lipid bilayer The Structure of the Cell Membrane Section 7-3 To concept map

  4. Cell Walls • Cell wall = provides support and protection for the cell • the cell wall is found in plant and fungi cells not animal cells

  5. Measuring concentration • The cytoplasm of a cell contains many different substances in water • The substances dissolved in the solution are called solutes • The concentration of a solution is the mass of the solute in the volume of solution • Example: 12 grams of salt in 4 liters of water is 12g/3L • The concentration is 3g/L

  6. Diffusion • In a solution molecules move constantly and randomly • Diffusion = molecules tend to move from an area of high concentration to an area of low concentration to spread out • When the concentration in the solution is the same throughout it is at equilibrium • Diffusion happens without having to use energy

  7. Osmosis • Many substances can diffuse across the membrane bus some are too large or strongly charged and cannot cross. • Water moves easily across the membrane • Osmosis = is the diffusion of water through a selectively permeable membrane • Water will move across the membrane until equilibrium is reached, at that point the concentration of water and solute will remain the same. This will mean they are isotonic

  8. Isotonic = same strength (equal amounts) • Hypertonic = above strength (more solute) • Hypotonic = below strength (less solute)

  9. Effects of Osmosis on Cells

  10. Facilitated Diffusion • Some molecules, such as Glucose, move across the cell membrane through protein channels • Facilitated diffusion= is when a protein in the cell membrane helps a molecule move across it

  11. Facilitated Diffusion Section 7-3 Glucose molecules High Concentration Cell Membrane Low Concentration Protein channel To concept map

  12. Active Transport • Active transport is when a cell uses energy to “pump” molecules across the membrane against the concentration gradient • Moving molecules from a low concentration to a high concentration • Requires energy!!

  13. Molecule to be carried Energy Molecule being carried Section 7-3 Active Transport To concept map

  14. Endocytosis • Endocytosis = is the process of taking material into the cell by means of infoldings, or pockets of the cell membrane • Endo = In

  15. Endocytosis – two types • Phagocytosis: extensions of cytoplasm surround a particle and package it within a food vacuole • Pinocytosis: tiny pockets form around the cell membrane, fill with fluid, and pinch off to form vacuoles

  16. Exocytosis • exocytosis: the membrane of the vacuole surrounding the material fuses with the cell membrane, forcing the contents out of the cell. • Exo = Out

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