Diffusion

What is diffusion?

• It is the net movement of particles from an area where there any many particles of the substance to an area where there are fewer particles of the substance.

  • Moving from “More to Less”

  • Substances diffuse from areas of High Concentration to Low Concentration.

• The amount of substance in a particular area is also called concentration.

What is facilitated diffusion?

• Usage of transport proteins to move other ions and small molecules across the plasma membrane.

  • Substances move into the cell through a water-filled transport protein ( channel protein ), which opens and closes to allow the substance to diffuse through the plasma membrane.

    • A Gateway

What is Osmosis?

• The diffusion of water across a selectively permeable membrane is called Osmosis.

• It regulates the movement of water across the plasma membrane, which is an key factor to maintain homeostasis within the cell.

What is an Isotonic Solution?

• Iso ( Greek Word ) = Equal.

• Water moves through the plasma membrane, but water enters and leaves at the same rate.

  • Enters / Leaves at the same time, therefore the cell is at equilibrium.

What is an Hypotonic Solution?

• Hypo ( Greek Word ) = Under.

• There is more water outside of the cell than inside.

• The result of Osmosis, the net movement of water through the plasma membrane is into the cell.

What is an Hypertonic Solution?

• Hyper ( Greek Word ) = Above.

• The concentration of the solute outside of the cell is higher than it is inside.

• During Osmosis, the net movement of water is out of the cell.

What is Active Transport?

• Substances move from a region of lower to higher concentration against the movement of higher to lower concentration.

  • movement of low to high against continuous flow of high to low concentration

• It is the movement of substances across the plasma membrane against a concentration gradient requires energy.

• Through Active Transport the cell maintains the proper balance of substances it needs.

  • Helping maintain homeostasis

What is Endocytosis?

• Substances that are too large to move through the plasma membrane by diffusion or transport proteins going through a different process.

• It is when a cell is surrounded by a portion of the plasma membrane at the outside environment. Then pinches off inside of the cell.

  • Think of En as Enter.

What is Exocytosis?

• The reverse process of Endocytosis.

• It is the process where the cell uses energy to expel waste and substances such as hormones that are produced by the cell.

  • Helping maintain homeostasis.

  • Think of Ex as Exit.