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A cell wall is the wall of a cell in plants, bacteria, fungi, algae, and some archaea. Animal cells do not have cell walls, nor do protozoa. Cell walls protect the cells from damage. It is also there to make the cell strong, to keep its shape, and to control the growing of the cell and plant.[1]
The cell wall is the tough, usually flexible but sometimes fairly rigid layer that surrounds some types of cells. It is outside the cell membrane and gives these cells support and protection, as well as acting as a filter. The cell wall also acts as a pressure vessel, preventing over-expansion when water enters the cell by osmosis.
The material in the cell wall varies. In plants and algae, the cell wall is made of long molecules of cellulose, pectin, and hemicellulose. The cell wall has channels which let some proteins in and keeps others out. Water and small molecules can go through the cell wall and the cell membrane.
Functions[edit]
The cell wall has many functions, first, cell wall helps cell to get definite shape and provide structure to support cell shape. Second, It can help cell not to lose water. Third, It aids in diffusion of gasses in and out of the cell and also provides mechanical protection from insects and pathogens.Fourth, it prevents the cell from rupturing due to turgor pressure.[2]
The bacteria cell wall is a good example. The bacteria has two different types of cell gram positive and gram negative. The names are from the reaction of the cells to gram staining.The cell wall is very important part of bacteria.The cell wall is one of the most important sites of attack by antibiotics. It also causes symptoms of disease in animals.
Differences between cell wall and cell membrane[edit]
the cell walls are outside the cell membrane and they are not part of the living cell[2]. A cell wall is different from a cell membrane. We say that a cell wall is dead but cell membrane is not since all cells have plasma membranes(membrane that are around the cell). Membranes are also semi-permeable[3], which means they select what goes in the cell and what does not.
The Cell wall is full permeable[4]. It let many molecules like ions, polysaccharides, other small molecules and low molecular weight proteins to go in the cell.The cell wall can lock water to slow down leaf transpiration, prevent the loss of water. Also, the cell wall is the channel of chemical signals and physical signals to the inside cell.
Middle lamella[edit]
Just like Cement is used to join two bricks same thing can be compared with middle lamella.The middle lamella gives cell shape, support, and strength.The middle lamella is made up of calcium and magnesium.From the name we think that it will be in the middle but it is not in middle but it is the outer part of cell.The middle lamella is the first wall of cell to give protection.
Animal cell membrane[edit]
As plant cell have a middle lamella,[5] Animal cell does not have cell wall they have microfilament(the thinnest filaments of the cytoskeleton). The plant cell has four protecting layer first is middle lamella second is primary cell wall third is secondary cell wall and the fourth is tertiary. Middle lamella store magnesium(a chemical element), so middle lamella play very important role in the plant cell.
References[edit]
- ↑ Cell Wall(link). {{{website}}}. Biology4Kids.
- ↑ 2.0 2.1 Carnagie and Leonard C. Bruno, Julie. "Cell Wall"(link). about education. 2001.
- ↑ http://www.thefreedictionary.com/semipermeable
- ↑ Permeability(link). The Free Dictionary. Houghton Mifflin Harcourt Publishing Company. 2011.
- ↑ Plant Cells, Chloroplasts, and Cell Walls(link). '. Scitable.
