Cytolysis in biology is the bursting of a cell caused by the influx of external liquid into the cell. This process is also known as osmotic lysis.
Understanding Cytolysis
Cytolysis occurs when a cell is in a hypotonic environment, meaning the concentration of solutes outside the cell is lower than inside the cell. As a result, water moves into the cell to equalize the solute concentrations.
How Water Enters the Cell
Water can enter the cell in two primary ways:
- Diffusion: Water passively diffuses across the cell membrane.
- Aquaporins: Water moves through selective membrane channels called aquaporins, which significantly speed up the flow of water.
The Process of Cytolysis
- Hypotonic Environment: The cell is surrounded by a fluid with a lower solute concentration.
- Water Influx: Water moves into the cell due to osmosis.
- Cell Swelling: The cell expands as water enters.
- Bursting: If the influx of water is excessive, the cell membrane can no longer contain the increased volume, and the cell bursts (lyses).
Cytolysis vs. Plasmolysis
It is helpful to compare cytolysis to a related phenomenon, plasmolysis, which occurs in plant cells.
Feature | Cytolysis (Animal Cells) | Plasmolysis (Plant Cells) |
---|---|---|
Environment | Hypotonic | Hypertonic |
Water Movement | Into the cell | Out of the cell |
Cell Appearance | Swells and bursts | Shrinks and detaches from cell wall |
Cause | Excessive water intake | Water loss |
Example
Imagine a red blood cell placed in distilled water. Distilled water has virtually no solutes. Since the inside of the red blood cell has a higher concentration of solutes, water will rush into the cell. Eventually, the red blood cell will swell and burst due to cytolysis.