Onion Cell Plasmolysis

Purpose



The purpose of this lab is to witness an onion cell in a hypertonic solution. By adding salt to an onion cell, the cell membrane will start to detach from the cell wall.

 

Method

The top image is the onion cell before plasmolysis. The bottom picture shows the same cells after adding salt.

 

This video shows the process of plasmolysis. The bright green substance is the cytoplasm pulling away from the cell wall. The shape of the cell wall is not affected by this change.  

 

Discussion

Plasmolysis is the shrinking of the cytoplasm away from the cell wall due to the diffusion of water out of the cell into a hypertonic solution. A hypertonic solution occurs when there is a higher solute concentration surrounding the cell. During plasmolysis, the central vacuole shrinks due to lack of water, which causes the cytoplasm to pull away from the cell wall. Plasmolysis is unlikely to occur naturally unless it's under severe conditions. For example, in the winter when salt is put on streets and sidewalks to get rid of ice, the salt diminishes the plants' water supply. In cases like this, plants tend to wilt due to lack of water.

 

 

References

Kim, Oliver. "Observing Plasmolysis." Microbe Hunter. Microbehunter, 2013. Web. 15 Oct. 2014.