Science- Diffusion and Osmosis
Diffusion and Osmosis
Diffusion
-the process by which molecules spread from areas of high concentratiion, to areas of low concentration. When the molecules are even throughout a space - it is called EQUILIBRIUM
DIFFUSION
Concentration gradient - a difference between concentrations in a space.
Molecules will always move down the concentration gradient, toward areas of lesser concentration. Think of food coloring that spreads out in a glass of water, or air freshener sprayed in a room.
Selectively Permeable - membranes that allow some things through, the cell membrane is selectively permeable, water and oxygen move freely across the cell's membrane, by diffusion
Osmosis - the diffusion of water (across a membrane)
Water will move in the direction where there is a high concentration of solute (and hence a lower concentration of water.
A simple rule to remember is: salt sucks
Salt is a solute, when it is concentrated inside or outside the cell, it will draw the water in its direction. This is also why you get thirsty after eating something salty.
Type of Solutions
ISOTONIC SOLUTIONS
If the concentration of solute (salt) is equal on both sides, the water will move back in forth but it won't have any result on the overall amount of water on either side.
HYPOTONIC SOLUTIONS
The word "HYPO" means less, in this case there are less solute (salt) molecules outside the cell, since salt sucks, water will move into the cell.
The cell will gain water and grow larger. In plant cells, the central vacuoles will fill and the plant becomes stiff and rigid, the cell wall keeps the plant from bursting
In animal cells, the cell may be in danger of bursting, organelles called CONTRACTILE VACUOLES will pump water out of the cell to prevent this.
HYPERTONIC SOLUTIONS
The word "HYPER" means more, in this case there are more solute (salt) molecules outside the cell, which causes the water to be sucked in that direction.
Diffusion
-the process by which molecules spread from areas of high concentratiion, to areas of low concentration. When the molecules are even throughout a space - it is called EQUILIBRIUM
DIFFUSION
Concentration gradient - a difference between concentrations in a space.
Molecules will always move down the concentration gradient, toward areas of lesser concentration. Think of food coloring that spreads out in a glass of water, or air freshener sprayed in a room.
Selectively Permeable - membranes that allow some things through, the cell membrane is selectively permeable, water and oxygen move freely across the cell's membrane, by diffusion
Osmosis - the diffusion of water (across a membrane)
Water will move in the direction where there is a high concentration of solute (and hence a lower concentration of water.
A simple rule to remember is: salt sucks
Salt is a solute, when it is concentrated inside or outside the cell, it will draw the water in its direction. This is also why you get thirsty after eating something salty.
Type of Solutions
ISOTONIC SOLUTIONS
If the concentration of solute (salt) is equal on both sides, the water will move back in forth but it won't have any result on the overall amount of water on either side.
HYPOTONIC SOLUTIONS
The word "HYPO" means less, in this case there are less solute (salt) molecules outside the cell, since salt sucks, water will move into the cell.
The cell will gain water and grow larger. In plant cells, the central vacuoles will fill and the plant becomes stiff and rigid, the cell wall keeps the plant from bursting
In animal cells, the cell may be in danger of bursting, organelles called CONTRACTILE VACUOLES will pump water out of the cell to prevent this.
HYPERTONIC SOLUTIONS
The word "HYPER" means more, in this case there are more solute (salt) molecules outside the cell, which causes the water to be sucked in that direction.