The main difference between tonoplast and plasma membrane is that tonoplast is the membrane that surrounds the central vacuole, whereas plasma membrane is the membrane that surrounds the cytoplasm of the cell.
Tonoplast and plasma membrane are two types of membranes that surround certain environments inside the cell. Tonoplast only occurs in plant cells while plasma membrane occurs in both animal and plant cells.
Key Areas Covered
1. What is Tonoplast
– Definition, Structure, Function
2. What is Plasma Membrane
– Definition, Structure, Function
3. Similarities Between Tonoplast and Plasma Membrane
– Outline of Common Features
4. Difference Between Tonoplast and Plasma Membrane
– Comparison of Key Differences
Key Terms
Plasma Membrane, Tonoplast
What is Tonoplast
Tonoplast is the semi-permeable, cytoplasmic membrane surrounding the vacuole of the cell. The vacuole of the cell is an important intracellular structure that occupies almost 90% of the cell volume. Plant vacuole contains fluid in which enzymes, proteins, amino acids, glucose, pigments, salts, and metal are dissolved. The main function of the tonoplast is to surround the central vacuole of the cell. Apart from that, it maintains the turgor pressure, the pressure generated by the fluid on the membrane. The tonoplast allows the passage of solutes in and out of the cell.
Figure 1: Tonoplast and Vacuole of a Plant Cell
Furthermore, tonoplast mainly occurs in plant cells. The vacuolar membrane is another name for tonoplast. It occurs around the vacuole of the cell. Therefore, the vacuole is a membrane-bound organelle. Apart from plant cells, vacuole occurs in fungal cells, protists, animal cells, and bacterial cells. In solution, the vacuole contains inorganic and organic molecules dissolving in it.
What is Plasma Membrane
Plasma membrane refers to a semipermeable barrier that surrounds cellular compartments. The plasma membrane that surrounds the cell is called the cell membrane. The plasma membrane also surrounds the organelles of eukaryotes. Typically, an organelle is a dynamic structure that performs a certain function inside the cell. Therefore, in order to perform their functions, the interior of the organelle should be a defined environment. The intracellular spaces of different organelles may also differ from each other. The maintenance of the homeostasis of the extracellular spaces inside the organelles is the function of the plasma membrane. Based on the function of the organelle, the structure of the plasma membrane that surrounds the organelle is also changed.
Figure 2: Plasma Membrane
Moreover, some plasma membranes are specialized to perform the functions of the organelles. For example, the mitochondrium is the organelle that performs cellular respiration in eukaryotes. Therefore, the mitochondrial membrane is specialized to perform the electron transport chain. The chloroplast membrane is also specialized to perform photosynthesis. Plant cell vacuoles are also enclosed by the plasma membrane
Similarities Between Tonoplast and Plasma Membrane
- Tonoplast and plasma membrane are two structures that occur in plant cells.
- They surround different structures of the cells and serve as a protective barrier.
- Both are semi-permeable membranes.
Difference Between Tonoplast and Plasma Membrane
Definition
Tonoplast refers to a membrane that bounds the chief vacuole of a plant cell, while plasma membrane refers to a microscopic membrane of lipids and proteins that forms the external boundary of the cytoplasm of a cell or encloses a vacuole and regulates the passage of molecules in and out of the cytoplasm.
Occurrence
Tonoplast only occurs in plant cells, while plasma membrane occurs in both plant and animal cells.
Structure
While the tonoplast surrounds the central vacuole of the plant cell, the plasma membrane surrounds the cytoplasm of the cell.
Other Names
The vacuolar membrane is another name for tonoplast, while the cell membrane is another name for the plasma membrane.
Function
Moreover, the tonoplast serves as a barrier between the cytoplasm and the content of the vacuole, while the cell membrane serves as the barrier between the interior and exterior of the cell.
Other Function
Tonoplast protects the content of the vacuole, but the plasma membrane protects the cytoplasmic content of the cell.
Significance
Tonoplast maintains the turgor pressure and regulates the movement of ions in and out of the cell while the plasma membrane controls the movement of substances, and participates in cell adhesion, cell signaling, ion conductivity, and attachment to surfaces.
Conclusion
In brief, the tonoplast and plasma membrane are two types of cellular structures that surround different structures of the cell. Tonoplast surrounds the central vacuole of plant cells. Therefore, it serves as a barrier between the cytoplasm and the content of the vacuole, protecting the contents of the vacuole. It also maintains turgor pressure and regulates the movement of ions between compartments. On the other hand, the plasma membrane is the membrane that surrounds the cell content from the outside environment. The main function of the plasma membrane is to serve as a barrier between the interior and exterior of the cell. It protects the cytoplasmic contents while allowing the movement of substances in and out and participating in cell adhesion, cell signaling, ion conductivity, and attachment to surfaces. Therefore, the main difference between tonoplast and plasma membrane is the structure and function.
References:
- “Tonoplast.” An Overview | ScienceDirect Topics.
- “Structure of the plasma membrane (article).” Khan Academy.
Image Courtesy:
- “Plant cell structure svg vacuole.” By Mariana Ruiz Lady of Hats. – Own work (Public Domain) via Commons Wikimedia
- “Celltypes” By Science Primer (National Center for Biotechnology Information) – Own Work ( Public Domain) via Commons Wikimedia
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