Objectives:

1
Osmosis

• Objectives
• 1) Explain how the processes of diffusion and
  osmosis occur and why they are important to
  cells.
• 2) Predict the effect of a hypotonic,
  hypertonic, or isotonic solution on a cell.

2
Diffusion

• Diffusion is the movement of particles from an
  area of higher concentration to an area of lower
  concentration.

3
Osmosis Diffusion of Water

• The diffusion of water across a selectively
  permeable membrane is called osmosis.
• Regulating the water flow through the plasma
  membrane is an important factor in maintaining
  homeostasis within a cell.

4
Osmosis Diffusion of Water

• Most cells whether in multicellular or
  unicellular organisms, are subject to osmosis
  because they are surrounded by water solutions.

5
Cells in an isotonic solution

• isotonic solution-
• ( concentrations)
• the concentration of dissolved substances in the
  solution is the same as the concentration of
  dissolved substances inside the cell.

H2O
H2O
Water Molecule Dissolved Molecule
6
Cells in an isotonic solution

• water molecules move into and out of the cell at
  the same rate, and cells retain their normal
  shape.

H2O
H2O
Water Molecule Dissolved Molecule
7
Cells in a hypotonic solution

• hypotonic solution dilute solution thus low
  concentration of dissolved substances
• In a hypotonic solution, water enters a cell by
  osmosis, to dilute high concentration of
  dissolved substances, thus causing the cell to
  swell.

H2O
H2O
Water Molecule Dissolved Molecule
8
Cells in a hypertonic solution

• hypertonic solution
• concentrated solution, thus a high
  concentration of dissolved substances
• In a hypertonic solution, water leaves a cell by
  osmosis, causing the cell to shrink

H2O
H2O
Water Molecule Dissolved Molecule
9
Summary

• Isotonic Concentrations of solution are equal
  outside and inside cell.
• Hypotonic Dilute or low concentration of
  dissolved substances outside the cell.
• Hypertonic High concentration of dissolved
  substances outside the cell.