 There are three possible relationships that cells can encounter when placed into a water solution: › 1. The concentration of solute in the solution can be equal to the concentration of solute in the cells. The cell is in an isotonic solution. (iso = same as normal) › 2. The concentration of solute in the solution can be greater than the concentration of solute in the cells. The cell is in an hypertonic solution. (hyper = more than normal) › 3. The concentration of solute in the solution can be l ess than the concentration of solute in the cells. The cell is in an hypotonic solution. (hypo = less than normal)

 Isotonic solution: A solution that has the same salt concentration as the normal cells of the body and the blood.salt  The cells remained the same in the isotonic solution

 The animal cell remains the same size in the isotonic solution because the concentration of solute (and therefore of water) is the same in the cell and in the isotonic solution, so as many water molecules move into the cell as move out of it.

 The cells shrivel up in the hypertonic solutions  In a hypertonic solution the concentration of water is greater in the animal cell than in the solution, so water leaves the animal cell and it shrinks. Water is again moving towards the greater solute concentration.

 The animal cells burst (lysed) in the hypotonic solution  The concentration of water is greater in the hypotonic solution than in the animal cell, causing the animal cell to swell and finally burst. The cell acts like a balloon filling with water. It expands until it can hold no more water and then shatters. Note that the water is moving into the greater concentration of solute.

 In an hypotonic solution, the cell will swell, but will not burst because of the rigid cell wall. Again, think of a balloon. This time the balloon is inside of a box. You can fill it with water until the balloon pushes against the sides of the box with enough force to bend the sides of the box outwards, but you will not be able to break the balloon. The pressure on the sides of the box is not enough to break the box and the balloon contained inside remains intact. The situation is the same with a plant cell. The pressure on the cell wall is not enough to break the wall. Pressure builds up and the cell wall bends outward, but it does not break. The pressure is called turgor pressure. Turgor pressure on the walls of plant cells is what keeps plants from drooping. Plants wilt without enough water to develop turgor pressure.