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What is cytolysis in biology?

Published in Cell Biology 2 mins read

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

  1. Hypotonic Environment: The cell is surrounded by a fluid with a lower solute concentration.
  2. Water Influx: Water moves into the cell due to osmosis.
  3. Cell Swelling: The cell expands as water enters.
  4. 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.