What is the Difference Between Plasmolysis and Haemolysis

The main difference between plasmolysis and haemolysis is that plasmolysis is the process of losing water from plant cells in a hypertonic solution, whereas haemolysis is the rupturing of red blood cells. Furthermore, plasmolysis occurs due to the loss of turgor pressure, while haemolysis occurs by the action of hemolysins, the toxins produced by certain pathogenic bacteria and fungi. 

Plasmolysis and haemolysis are two processes that make cells to lose their function. Both are influenced by external factors. During plasmolysis, the protoplasm of the cell peels away from the cell wall, leaving gaps between the cell wall and the cell membrane while during haemolysis, red blood cells release their contents into the plasma.  

Key Areas Covered 

1. What is Plasmolysis
     – Definition, Process, Importance
2. What is Haemolysis
     – Definition, Process, Importance
3. What are the Similarities Between Plasmolysis and Haemolysis
     – Outline of Common Features
4. What is the Difference Between Plasmolysis and Haemolysis
     – Comparison of Key Differences

Key Terms 

Alpha Hemolysis, Beta Hemolysis, Concave Plasmolysis, Convex Plasmolysis, Gamma Hemolysis, Haemolysis, Osmosis, Plasmolysis, Turgor Pressure

What is Plasmolysis 

Plasmolysis is the loss of water from the cytoplasm of a plant cell when placed in a hypertonic solution. Here, the water potential of the cytoplasm is higher than the water potential of the outside solution. Therefore, water molecules move through the cell membrane to the outside solution until the inside and outside water potentials become equal. Moreover, the process of moving water through a semipermeable membrane like the cell membrane is known as osmosis. Since this osmosis occurs towards the outside, it is known as exosmosis. Additionally, with the loss of water, the turgor pressure of the cytoplasm also gradually drops.

Figure 1: Concave Plasmolysis of Rhoeo

Furthermore, there are two types of plasmolysis based on the effect on the protoplasm. They are concave and convex plasmolysis. In concave plasmolysis, the protoplasm shrinks away from the cell wall, detaching it to form half-moon-shaped pockets in between. Generally, concave plasmolysis can be reversed when placed in the hypotonic solution with the higher water potential than the cytoplasm. However, convex plasmolysis is severe than concave plasmolysis in which the protoplasm completely detaches from the cell wall in a process called cytorrhysis. Generally, it is not reversible.  

What is Haemolysis 

Haemolysis is the rupturing or lysis of the red blood cells, releasing its content into the surrounding fluids. Since it occurs through the damage to the cell membrane, red blood cells that undergo hemolysis eventually die. Hemolysins are the toxins produced by pathogens such as bacteria and fungi, causing hemolysis. Many Gram-positive bacteria (e.g., Streptococcus, Enterococcus, and Staphylococcus) and some parasites (e.g., Plasmodium), cause hemolysis in vivo. Moreover, some autoimmune diseases such as drug-induced hemolytic anemia and some genetic diseases such as sickle-cell disease and G6PD deficiency cause hemolysis. 

Figure 2: Alpha, Beta, and Gamma Hemolysis

Furthermore, in vitro, three types of hemolytic reactions can occur. They are alpha hemolysis, beta hemolysis, and gamma hemolysis. Alpha hemolysis produces dark to green color colonies due to the oxidized hemoglobin from the partially hemolyzed red blood cells. Meanwhile, beta hemolysis results in the complete rupture of red blood cells, appearing transparent and yellow color areas on the agar. Gamma hemolysis occurs due to the presence of non-hemolytic pathogens in the medium. Hence, the color of the red cell colonies remains unchanged.

Moreover, hemolysis can occur due to the placement of red blood cells in a hypotonic solution. Here, in contrast to plasmolysis, water from the outside solution moves into the cytoplasm of red blood cells by endosmosis. Further, due to the lack of a cell wall, red blood cells rupture.  

Similarities Between Plasmolysis and Haemolysis 

• Plasmolysis and haemolysis are two processes that occur in different types of cells. 
• Both processes destroy the regular functioning of these cells. 
• Also, both affect the properties of cytoplasm. 

Difference Between Plasmolysis and Haemolysis 

Definition 

Plasmolysis refers to the contraction of the protoplast of a plant cell as a result of the loss of water from the cell, while haemolysis refers to the destruction of red blood cells, which leads to the release of hemoglobin from within the red blood cells into the blood plasma. Thus, this describes the main difference between plasmolysis and haemolysis.

Significance 

Furthermore, plasmolysis is the process of losing water from plant cells in a hypertonic solution, whereas haemolysis is the rupturing of red blood cells. 

Causes 

Plasmolysis occurs due to the loss of turgor pressure, while haemolysis occurs by the action of hemolysins, the toxins produced by certain pathogenic bacteria and fungi. Hence, this is another difference between plasmolysis and haemolysis.

Process 

During plasmolysis, the protoplasm of the cell peels away from the cell wall, leaving gaps between the cell wall and the cell membrane, while during haemolysis, red blood cells release their contents into the plasma.  

Cell Lysis 

Importantly, plasmolysis does not result in cell lysis, while haemolysis results in cell lysis. 

Reversibility 

Also, reversibility is another difference between plasmolysis and haemolysis. Plasmolysis is reversible, while haemolysis is irreversible. 

Result in 

Besides, one other difference between plasmolysis and haemolysis is that plasmolysis results in the wilting of plants, while haemolysis results in hemolytic anemia. 

Types 

The two types of plasmolysis are concave plasmolysis and convex plasmolysis while the three types of haemolysis in vitro are the alpha hemolysis, beta hemolysis, and gamma hemolysis. 

Conclusion 

Plasmolysis is a result of exosmosis in which water from the cytoplasm of plant cells moves to the outside hypertonic solution. As a result of losing water, cytoplasm shrinks and peels off from the cell wall. However, plasmolysis is reversible, and the reverse process is known as deplasmolysis. In contrast, haemolysis is the rupture of red blood cells to release its content to the plasma. Moreover, this rupturing occurs due to a toxin released by pathogenic cells. However, hemolysis is not a reversible process. Therefore, the main difference between plasmolysis and haemolysis is the type of process and result. 

References:

1. “Plasmolysis – Definition, Types and Examples.” Biology Dictionary, 29 Mar. 2019, Available Here.
2. “Blood Agar, Hemolysis, and Hemolytic Reactions.” World of Microbiology and Immunology, Encyclopedia.com, 2019, Available Here.

Image Courtesy:

1. “Rhoeo Discolor – Plasmolysis” By Mnolf – Photo taken in Innsbruck, Austria (CC BY-SA 3.0) via Commons Wikimedia   
2. “Streptococcal hemolysis” By Y tambe – Y tambe’s file (CC BY-SA 3.0) via Commons Wikimedia