|Edwards I. Gabrielle. Biology The Easy Way, 2nd ed. New York: Barron's Educational Series, Inc, 1990: Page 63.||"Ranging from 5 to 80 nm in diameter, the walls of prokaryotic cells get their tensile strength from murein."||5-80 nm|
|Nazamid Saari. Cell Structure and Function [pdf]. Universiti Putra Malaysia.||"Eucaryotic cell walls differ significantly in composition and physical structure from procaryotic cell walls. Thickness~ 20 nm. Consists of cellulose, hemicelulose, pectin; fungi- chitin, beta glucans, mannan in yeast; no cell walls on animal cells or protozoa. To provide protection, strength and shape."||20 nm|
|Paustian, Timothy. Cell Wall. University of Wisconsin-Madison, 2003.||
|Cosgrove J. Daniel. Assembly and Enlargement of the Primary Cell Wall in Plants [pdf]. Pennsylvania State University, 1997.||"McCann et al (1990) emphasize the thickness (100 nm) and architectural simplicity of the primary wall of the union bulb."||100 nm|
All living organisms are made out of cells. Everything in our body or another organism's body is composed of cell. Since cells are so tiny, there are so many of them in us and other organisms. Our skin, muscles, hair, nails … everything really is made out of cells. Organisms that are made of only one cell are called unicellular and organisms that are made of more than one cell are called multicellular.
Even though cells are tiny they are composed of many parts (those parts are called organelles). Many of these organelles are similar for both animals and plants but plants also have a cell wall which animal and human cells do not have. The cell wall is usually present in plant and bacteria cells. In plant cells there is a primary and a secondary cell wall. The primary cell wall is made out of pectin while the secondary cell wall is made out of cellulose. The plant cell walls are different in their thickness, but usually they are less than 100 µm thick. Most bacteria also have cell walls. In bacteria, there are two types of cell walls. The gram positive bacteria and the gram negative bacteria. The gram positive cell walls are much thicker than the gram negative ones. The gram positive cell wall is usually between 20 and 80 nm thick while the gram negative cell wall is usually between 5 and 10 nm thick.
The cell wall forms a boundary around the cell, to support and protect the cell. It protects it from dryness and infection. The cell wall in both plants and bacteria is very important because it allows them to survive.
Alona Vorobyov -- 2003