Plant cells are similar to animal cells in both internal function and processes. Both cells contain mitchondria and ribosomes to help process energy and nutrients. However, plant cells have an extra feature that animal cells do not have called the cell wall. The cell wall serves several unique purposes for a plant cell, including the plant cell's interaction with water.
The Plant Cell Wall
Plant cell walls are rigid membranes that cover over the cell. The cell wall provides a structured shape for the cell, helping the cell retain its form. The cell wall also controls the rate of replication, allowing plant cells to replicate at a much slower rate than animal cells. The cell wall helps to form the plant cell, but it also helps keep much of the internal functions of the cell, such as processing water, inside the plant.
Protecting Important Nutrients
A cell wall allows water to work its way into the cell body. The cell wall can do this because the structure of the wall is porous. This allows water, at its smallest molecule, to pass into the cell without organisms like pathogens and bacteria entering into the cell. The walls can also process minerals, specifically minerals found in the dirt underneath the root. Water helps flow these nutrients through the cell wall and into the internal mechanisms of the cell. At the same time, the water is unable to escape. The cell wall captures and pressurizes the water within the cell, keeping the cell properly hydrated.
Crossing The Walls
A plant cell has three layers of walls. The middle lambella is a wall that connects plant cells with other plant cells with complex proteins. After the lambella is the primary wall, which is the rigid skeletal enclosure for the cell itself. After the primary wall is the secondary wall. This plant cell wall is a compressed wall that pressurizes the inside of the cell. When water hits a plant cell wall, the water molecules pass through the more porous levels of the lambella and the primary wall. When water makes it through to the secondary wall, it moves through the microscopic fibers of the secondary wall, but is then pressurized within the cell. This allows the plant cell to keep in the water it absorbs.
Although plant cells, like any cell, requires water, the plant cell's hard wall allows water to pass in and stay in within the cell. However, the plant cell wall protects the rest of the cell from over-saturation. Unlike an animal, a plant does not seek water; water comes to plants through perception, for example. Hence, a plant cell requires adequate protection from over-saturation of water. The cell wall of a plant cell, through the lambella and the primary wall, are made of compounds known as lipids, which are basically molecules of fats and waxes. The lipids can waterproof the cell from over-saturation, allowing a finite amount of water through to the secondary wall.