| MadSci Network: Cell Biology |
Dear Jackie,
The electron microscope has indeed shown us a little about the appearance
of the cell membrane--on high magnification electron micrographs, it
appears as a very thin structure with 2 dark staining layers on each side
of a pale staining layer. In actual fact, though, EM's don't really tell
us much more than this! Most of the information about the cell membrane
comes from other methods: eg., masses of pure cell membranes can be
obtained by bursting red blood cells, which have no organelles, and
purifying the remaining membrane. These biochemical approaches have
identified the proteins that are abundant in the cell membrane, such as the
"Band 3" bicarbonate transporter protein, and also proteins that attach to
the cell membrane to support it, such as spectrin. Analysis of the amino
acid sequences of membrane proteins let us understand the shape of these
proteins and how they are inserted into the lipids of the membrane. You
can find out more details like these in my book on cells ("Cells: amazing
forms and functions" by J. K. Young, Franklin-Watts, Sydney Aust., 1990)
which might be in your school library. A more in depth book about cells is
called "Molecular biology of the Cell" by Bruce Alberts, et al. You can
access this book on the Web for free at www.ncbi.nlm.nih.gov/Literature.
Try the links in the MadSci Library for more information on Cell Biology.