The key difference between crenation and plasmolysis is that crenation is the shrinkage and acquiring of a notched appearance by red blood cells when exposed to a hypertonic solution while plasmolysis is the shrinkage of plant cells when immersed in a hypertonic solution.
The cell membrane is permeable to water. When a cell is immersed in a solution which has low water potential and high solute potential, the cell loses its water by osmosis. The solution is considered to be a “hypertonic solution”. Since plant cells differ from animal cells due to the presence of a rigid cell wall, the changes are different when they are immersed in a hypertonic solution. Crenation is the term used to explain the changes occurring in red blood cells when they are immersed in a hypertonic solution. It is the state of becoming shrunken with a notched edge. Plasmolysis is the term that describes the changes occurring in plant cells when they are immersed in a hypertonic solution.
CONTENTS
1. Overview and Key Difference
2. What is Crenation
3. What is Plasmolysis
4. Similarities Between Crenation and Plasmolysis
5. Side by Side Comparison – Crenation vs Plasmolysis in Tabular Form
6. Summary
What is Crenation?
Crenation is the shrunken notched appearance of red blood cells when exposed to a hypertonic solution. Hence, the term crenation is mainly used to explain the state of being shrunken by red blood cells with a notched edge when exposed to an extremely salty solution. Crenation is a result of osmosis and water loss. When the isotonic state of red blood cells is disrupted, they convert into this abnormal notched appearance.
Figure 01: Crenation shown by Red Blood Cells
What is Plasmolysis?
Water molecules move across a concentration gradient via a semi-permeable membrane from a higher water potential to lower water potential. Hence, when a cell is placed on a hypertonic solution, water will flow out of the cell in order to get the ionic concentration of the internal and external environment to equilibrium. This process is referred to as exosmosis. Until the water potentials are balanced, water will move out of the cell to the solution. During this process, the protoplasm starts to detach from the cell wall. This is known as plasmolysis. Plasmolysis takes place under extreme pressure and can be induced under laboratory conditions by using high concentrated saline solutions.
Figure 02: Plasmolysis
There are two types of plasmolysis as concave plasmolysis or convex plasmolysis. Concave plasmolysis is reversible. During this type of plasmolysis, the plasma membrane does not completely detach from the cell wall; instead, it remains intact. Convex plasmolysis, on the other hand, is irreversible and is the extreme level of plasmolysis where the cell plasma membrane completely detaches from the cell wall. This can lead to the complete destruction of the cell.
What are the Similarities Between Crenation and Plasmolysis?
- Crenation and plasmolysis take place when the cells are dipped in a hypertonic solution.
- Both processes are a result of osmosis.
- In both processes, water moves from the cell to the outside solution.
- Cells shrink in both processes.
- In both instances, the water potential of the cell is higher than the water potential of the solution.
What is the Difference Between Crenation and Plasmolysis?
Crenation takes place in animal cells while plasmolysis takes place in plant cells. Crenation is the response of red blood cells when exposed to a hypertonic solution, while plasmolysis is the typical response of plant cells when exposed to a hypertonic solution. So, this is the key difference between crenation and plasmolysis.
Moreover, in crenation, the red blood cells become shrunken with a notched edge while in plasmolysis, the plant cells become shrunken, and the protoplasm shrinks away from the cell wall.
Summary – Crenation vs Plasmolysis
Crenation is the process of red blood cells being shrunken with a notched edge when exposed to an extremely salty solution, while plasmolysis is the process of plant cells being shrunken when immersed in a hypertonic solution. Thus, this is the key difference between crenation and plasmolysis.
Reference:
1. “Plasmolysis”. Biology Dictionary, 2020, Available here.
2. “What Is Crenation In Chemistry?”. Thoughtco, 2020, Available here.
Image Courtesy:
1. “Osmotic pressure on blood cells diagram” By LadyofHats – (Public Domain) via Commons Wikimedia (Cropped)
2. “Rhoeo Discolor – Plasmolysis” By Mnolf – Photo taken in Innsbruck, Austria (CC BY-SA 3.0) via Commons Wikimedia