What is the Difference Between Living and Dead Cells

The main difference between living and dead cells is that living cells have an intact cell membrane that acts as a barrier whereas the cell membrane of the dead cells allows passing dyes into the dead cell.

Living cells and dead cells are two types of cells one can identify when examining a cell sample. Both living cells and dead cells contain cell membranes and other organelles.

Key Areas Covered

1. What are Living Cells
   • Definition, Features, Importance
2. What are Dead Cells
   • Definition, Features, Importance
3. Similarities Between Living and Dead Cells
   • Outline of Common Features
4. Difference Between Living and Dead Cells
   • Comparison of Key Differences

Key Terms

Dead Cells, Living Cells, Microscopic Examination of Cells

What are Living cells

A living cell is the smallest part of an animal or plant that is able to function independently. The main feature of a living cell is that it is intact. That means the cell membrane of the living cell remains intact. This cell membrane serves as a selectively permeable barrier to different substances. In microscopic examinations, living cells do not take different dye materials into the cell. Therefore, under the microscope, living cells are not stained.

Figure 1: Plant Cell

Furthermore, the prominent components of a living cell include the nucleus, ribosomes, mitochondria, chloroplasts, etc.  The nucleus is the membrane-enclosed organelle within a cell that contains the chromosomes. Ribosomes are minute particles consisting of RNA and associated proteins found in large numbers in the cytoplasm of living cells. Usually, they bind messenger RNA and transfer RNA to synthesize polypeptides and proteins. Mitochondria are organelles found in large numbers in most cells; the biochemical processes of respiration and energy production in the cell occur here. It has a double membrane, the inner part being folded inwards to form layers. Chloroplasts are the plastids in green plant cells that contain chlorophyll and in which photosynthesis takes place.

What are Dead Cells

Dead cells are cells that are not intact. Therefore, these cells do not contain an intact cell membrane. Due to this reason, different materials can get into a dead cell. The main method to identify dead cells is using a cell-impermeant DNA binding dye such as propidium iodide. In general, a healthy living cell has an intact cell membrane that will act as a barrier to the dye. Therefore, the dye cannot enter the cell. However, a dead cell has a compromised cell membrane, and it will allow the dye into the cell to bind to the DNA and become fluorescent. Dead cells therefore will be positive while live cells will be negative.

Figure 2: Dead Cells in the Xylem

Later, dead cells can deteriorate into debris. One can identify different pieces of debris from a single cell as separate dead cells. Fluorescent labeling of cells can avoid this matter and identify whole dead cells from cell debris. Normally,  fluorescently-labeled whole cells create two distinct intensity rings in the far-field, in contrast to fluorescently-labeled cell debris, which only creates one ring.

Similarities Between Living and Dead Cells

• Living cells and dead cells are two types of components in a cellular mixture that one should distinguish in a cell sample.
• Both living cells and dead cells contain cell membranes and other organelles.

Difference Between Living and Dead Cells

Definition

Living cells are the smallest part of an animal or plant that is able to function independently while dead cells are the cells that have undergone necrosis.

Importance

Living cells have an intact cell membrane while the cell membrane of the dead cells is not intact.

Staining

Living cells are not stained while dead cells undergo staining.

Functionality

Living cells are functional while dead cells are not functional.

Conclusion

In brief, living cells and dead cells are two types of cellular components that can occur in the sample for microscopic observation. Living cells have an intact cell membrane that does not allow the stains to pass through into the cell. However, dead cells do not have an intact cell membrane and all the stains can go into the cell. Therefore, only dead cells are stained under the microscope. In addition, living cells are functional cells while dead cells are not functional. Thus, the main difference between living cells and dead cells is their functionality.

References:

1. Muhammad A. Talukder, Curtis R. Menyuk, and Yordan Kostov “Distinguishing between whole cells and cell debris using surface plasmon coupled emission (Conference Presentation)“, Proc. SPIE 10068, Imaging, Manipulation, and Analysis of Biomolecules, Cells, and Tissues XV, 100680D (24 April 2017).
2. Wikimedia Foundation. (2022, August 17). Cell (biology). Wikipedia. Retrieved August 25, 2022.

Image Courtesy:

1. “Plant cell structure-en ” By LadyofHats – Own Work (Public Domain) via Commons Wikimedia
2. “Xylem rays (Tilia Americana)” By Adree.stem – Own Work (CC BY-SA 4.0) via Commons Wikimedia