Parenchyma cells are a type of cell found within most plants. Like animals, plants have cells that are specialized for different functions. Parenchyma cells are simple cells that are not specialized, but they do occur within almost all plant tissues. Cells that are found within plants are often grouped into a specific type based on the size of the cell wall surrounding the cell and also if the cell is living or dead. Other types of cells that make up tissues within plants are collenchyma cells and sclerenchyma cells.
Each parenchyma cell is surrounded by a thin cell wall that contains cellulose. Within the cell well is the cell membrane, which controls what enters and leaves the cell. The center of the cell is filled by a very large vacuole and all the other organelles, including the nucleus and chloroplasts, are found pushed to the edge of the cell by the vacuole.
If the vacuole within the cell is full of water, it is said to be turgid. Packed together in the stems and leaves, turgid parenchyma cells provide support for herbaceous plants. These types of plants do not have a woody stem, so they die down to the soil level at the end of each growing season.
These cells are usually round, or spherical, in shape, but they can be pushed into other shapes by the cells that are surrounding them. Most processes of plant metabolism occur within parenchyma cells, and due to the large vacuole, they can be used to store food and water. When studying plant cells, these are often the types of cells that are observed due to their simplistic nature.
Almost every part of a non-woody plant has some parenchyma cells within it. Depending on where the cell is found, it carries out a different function. The fact that different functions occur with a parenchyma cell in different parts of the plant means that the structure of the cell can also vary.
The area where parenchyma cells are found within leaves is called the mesophyll. Due to the fact that they contain chloroplasts, the cells appear green. This means that photosynthesis takes place within these cells. During the process of photosynthesis, carbon dioxide and water is converted into glucose and oxygen. Energy for the process is obtained from sunlight.
Once glucose is produced, it can then be stored in the parenchyma cells found within other parts of the plant. In most cases, storage takes place within the roots of a plant. Food can also be stored within tubers, seeds and fruits that the plant produces.