What happens when a cell becomes larger than the limits to cell size?
A cell will lyse if it becomes bigger than the limits of its cell size. In other words, the cell will “pop” or “explode.”
The tonicity of a solution refers to the solution’s solute concentration. A solute is the substance that is dissolved in a solvent. A hypertonic solution contains more solutes than its surroundings (“hyper” = more than). A hypotonic solution contains less solutes than its surroundings (“hypo” = less than). When two solutions are isotonic to one another, they contain the same amount of solutes.
A cell will lyse when placed in a hypotonic solution because of osmosis. Osmosis is the diffusion of water down its concentration gradient. In other words, water moves from an area of higher concentration to an area of lower concentration during osmosis. When compared to the tonicity of a cell, a hypotonic solution contains less solutes and more water. Thus, the water will move from the hypotonic solution and into the cell via the cell’s membrane. If the tonicity difference between the cell and the hypotonic solution is great enough, then the cell will lyse because of all the water that rushes into it.