|MadSci Network: Cell Biology|
Firstly the most obvious, both are three dimensional many people think of cells as flat. A scanning electron micrograph of a cell clearly shows them as nearly spherical. However while a bubble is perfectly spherical a cell may have some rigidity and alternative shape, especially when amongst other cells in tissues and organs of the body. A single cell in a solution would be almost spherical. More technically if one leaves aside the contents of a cell, an empty cell, the similarities are quite significant. A bubble is made of soap, a detergent. A cells membrane is made of fat, or lipids. Both detergents and lipids have an extremely similar chemical structure and behave in an almost identical way. They are described as “polar”. They both have a polar head that which is hydrophilic (water loving) and non-polar tail that is hydrophobic (water hating). The tails (repelling against any water) will all point into the center providing a protective ring of polar heads that happily interact with the surrounding water in any solution – this is called a lipid or detergent “micelle”. In a similar way, detergents in water form microscopic bubbles or micelles. If you increase the size of your micelle (detergent or lipid) it will form a bilayer with an inside and outside ring of polar bodies with their tails pointing together and their heads to the outside and inside. This is the basis of a cell membrane and also a bubble. In a cell the inside is filled with cellular organelles and cytoplasm, in a bubble the inside is filled with air. Any cell textbook should have a picture of a lipid micelle and lipid bilayer.
Try the links in the MadSci Library for more information on Cell Biology.