Experiment 5.4PLASMOLYSIS AND TURGIDITY OF PLANT CELLS

Prepared by:Mark John G. Girasol

Eihmile Kreistein N. Salgado

I. Introduction

Turgidity happens when a plant cell has reached a stage when there is no flow of water between the external surroundings and the vacuole. As a result, the plant becomes turgid. This basically results from a hypotonic solution where the water potential of the cell is less than that of its environment. So the movement of water is towards the cell. The vacuoles push the organelles to the plasma membrane and the plasma membrane to the cell wall. This is called the turgor pressure. This force is enough to keep the growing portions of the plant upright. Although we may consider excess of turgidity as something that would eventually make the plant cell burst, the cell wall prevents the cell to experience cytolysis. So basically, a plant cell does not experience cytolysis.

Plant cell in hypotonic solution Plant cell in hypertonic solution

II. Objective

To demonstrate plasmolysis and turgidity in plant cells

III. Hypothesis

The turgidity of a normal plant cell will not be the same after undergoing plasmolysis and deplasmolysis.

IV. Review of Related Literature

Rhoeo discolor contains a water-solluble pigment called anthocyanin which is dissolved

in the vacuoles of its lower epidermis. We may be confused that there are some pigments that are found in the chromoplasts. These types of pigments are not water-solluble. Therefore, they cannot thrive in the vacuoles.

The plant's cell wall is non-living. It is not a part of the cell. Consequently, it cannot perform the job of the plasma membrane to regulate the passage of molecules. Therefore, it is permeable to any substance.

The vacuole is a membrane-bound organelle. Its semi-permeable membrane is called the tonoplast.

Osmosis is the diffusion of water from a region of high water potential to a region of low water potential across a semi-permeable membrane.

V. Methodology

A. Materials

• Rhoeo discolor• Glass slide and cover slip• Dissecting needle• Razor blade• Compound microscope• Water• 30% sugar solution• Dropper

B. Procedures

1. A small portion of the Rhoeo discolor’s lower epidermis was stripped off with the use of a razor blade.

2. The specimen was mounted to the glass slide.3. It was studied under the LPO.4. Cells containing anthocyanin(with purple pigments) were located.5. The magnification was shifted to HPO.6. The small portion stripped off from Rhoeodiscolor was flooded with sugar solution at

the side of the cover slip.7. Changes in the cell were observed.8. The sugar solution was removed through a tissue paper which would absorb it.9. The specimen was again flooded with tap water.10. The cell was once again examined after being deplasmolyzed.

VI. Results

Before we plasmolyze the cells of Rhoe discolor's we first view the normal cells under the microscope. We can see that most of the cells are very full of purple pigments. This is an evidence of swollen vacuoles. In this state, the cell is turgid.

After we put the 30% sugar solution, we examined the specimen under the microscope. And we came up with this illustration. As we can see here, the vacuoles containing the anthocyanin pigment shrank. It is very evident that the plant cells were plasmolyzed.

Lastly, after we removed the sugar solution flooded on the specimen, we put, for the second time, tap water and examined it under the microscope. The vacuoles of the cell turned bigger but not the same as what we can see when the cells are still normal.

Normal Cells

Plasmolyzed Cells

Deplasmolyzed Cells

VII. Conclusion

A plant cell’s turgidity after deplasmolysis will eventually be the same as that of the normal plant cell. The water potential of the cytoplasm during plasmolysis is greater than that of the environment. So water moves outside of the cell and during deplasmolysis, it once again enters the cell because there is a greater water potential in the environment.

There are varying sizes of the vacuoles during plasmolysis because every vacuole has a different concentration of anthocyanin. Those that have less water potential didn't really shrink after plasmolysis and those that have much are the ones that are the smallest.

Due to some unavoidable factors like not getting all of the sugar molecules of the sugar solution flooded into the specimen, and that some of the cells died which made them irrevivable, the cells didn't somehow get back it's original appearance.

The plant cell’s turgidity will be back to original only if the water concentration of the cell’s environment during deplasmolysisis the same as that when the plant cell is normal.