Homeostasis

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Homeostasis Transport
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Section 1 Diffusion Osmosis
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Homeostasis

• Homeostasis the biological balance between a
  cell or an organism and its environment
• Cells maintain homeostasis by controlling and
  regulating what gets into and out of the cell.

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Diffusion

• Diffusion the process by which molecules move
  from an area of greater concentration to an area
  of lower concentration

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Diffusion
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BrownianMotion

• Brownian Motion molecules are in a constant
  state of random motion

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BrownianMotion
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Concentration Gradient

• Concentration Gradient the difference in
  concentration of a substance across a space

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Dynamic Equilibrium

• Dynamic Equilibrium a state that exists when the
  concentration of a substance is the same
  throughout a space

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Dynamic Equilibrium
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Review of Cell Membrane Structure
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Diffusion Across Membranes

• Not all molecules can diffuse through all
  membranes.
• The ability of a molecule to pass through a
  membrane depends on the size and type of molecule
  and the molecular structure of the membrane.

Small nonpolar molecules can diffuse through the
cell membrane
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Osmosis

• Osmosis the diffusion of water molecules through
  a selectively permeable membrane from an area of
  high water concentration to an area of lower
  water concentration

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Osmosis
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Three Types of Solutions
90 H2O 10 solute
85 H2O 15 solute
95 H2O 5 solute
90 H2O 10 solute
90 H2O 10 solute
90 H2O 10 solute
Hypotonic
Hypertonic
Isotonic (no net movement of water)
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Three Types of Solutions
Plant Cells
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Three Types of Solutions
Animal Cells
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Three Types of Solutions
Cytolysis
Plasmolysis
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Three Types of Solutions
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Contractile Vacuoles

• Contractile Vacuole an organelle in
  microorganisms that excretes water
• collect excess water ? contract ? squeeze out
  water

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Study the diagram below. It represents a
container that is divided by a semipermeable
membrane. A different solution in its initial
state is shown on each side of the membrane.
1. Describe which molecule(s) will move through
the membrane and which molecule(s) will
not. 2. Describe the relative rates at which the
molecule(s) will move across the
membrane. 3. Describe in which direction the
molecule(s) will move. 4. Describe how long the
molecule(s) will continue to move.
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Section 2 Other Kinds of Transport
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Review of Cell Membrane Structure
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Review of Cell Membrane Structure
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Passive Transport

• Passive Transport the movement of any substance
  across a cell membrane without the use of cell
  energy
• Diffusion
• Osmosis
• Facilitated Diffusion
• Gated Channel

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Facilitated Diffusion

• Facilitated Diffusion a process in which
  substances move down their concentration gradient
  across the cell membrane with the assistance of
  carrier proteins
• Examples glucose, fructose, ions

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FacilitatedDiffusion
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Facilitated Diffusion
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Gated Channel

• Gated Channel a protein-lined gated passage
  making cell membranes permeable to certain large
  molecules as needed
• Example neuromuscular function

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Gated Channel
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Active Transport

• Active Transport the movement of any substance
  across a cell membrane with the use of energy
  from ATP
• Sodium-Potassium Pump
• Endocytosis
• Exocytosis

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Sodium-Potassium Pump

• Sodium-Potassium Pump an active transport
  mechanism that moves ions in order to achieve
  polarization

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Proton Pump

• Proton Pump an active transport mechanism that
  consumes ATP (energy) to force Hydrogen ions
  against the concentration gradient

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Proton Pump
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Proton Pump
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Endocytosis

• Endocytosis the process by which a cell engulfs
  and surrounds large substances

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Endocytosis
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Exocytosis

• Exocytosis the process by which wastes are
  packaged in vesicles and leave the cell

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Exocytosis
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Passive vs.ActiveTransport
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Passive vs. Active Transport
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