The membrane surrounding the vacuole of a plant cell is called the tonoplast. The tonoplast is a selectively permeable membrane that separates the vacuole from the cytoplasm of the cell. It plays a crucial role in maintaining the integrity and functionality of the vacuole.

1. Structure of the Tonoplast:
The tonoplast is a single lipid bilayer membrane that surrounds the vacuole. It is composed of phospholipids, proteins, and various other molecules. The presence of transport proteins in the tonoplast allows for the movement of ions, nutrients, and other molecules into and out of the vacuole.

2. Functions of the Tonoplast:
The tonoplast has several important functions in plant cells:

- Storage: The vacuole is a major storage compartment in plant cells, and the tonoplast helps maintain the osmotic balance and stores various compounds such as water, ions, nutrients, pigments, and toxins.

- Transport: The tonoplast contains transport proteins that facilitate the movement of molecules into and out of the vacuole. It regulates the uptake and release of ions and nutrients, maintaining the internal environment of the vacuole.

- pH Regulation: The tonoplast is involved in regulating the acidity (pH) of the vacuole. It maintains an acidic pH inside the vacuole, which is essential for various cellular processes and enzyme activities.

- Detoxification: The vacuole acts as a storage site for toxic compounds that are harmful to the cell. The tonoplast plays a role in sequestering and isolating these toxic substances within the vacuole, protecting the rest of the cell.

3. Comparison with Other Cell Membranes:
The tonoplast is distinct from other cell membranes, such as the plasma membrane and nuclear membrane, in terms of its composition and function.

- Plasma Membrane: The plasma membrane surrounds the entire cell and regulates the exchange of materials between the cell and its external environment. It is involved in processes such as nutrient uptake, waste elimination, and cell signaling. The tonoplast, on the other hand, specifically surrounds the vacuole and is responsible for its storage and transport functions.

- Nuclear Membrane: The nuclear membrane, also known as the nuclear envelope, encloses the nucleus of the cell. It regulates the movement of molecules between the nucleus and the cytoplasm. The tonoplast, however, is not directly involved in nuclear functions and is primarily associated with the vacuole.

In summary, the tonoplast is the membrane surrounding the vacuole in plant cells. It is involved in the storage, transport, pH regulation, and detoxification functions of the vacuole. It is important for maintaining the internal environment and overall functioning of the plant cell.

The membrane surrounding the vacuole is Tonoplast.