Biomedical Engineering Reference
In-Depth Information
Figure 5.4
Growth of a cell tip.
howcellswork.Inthefollowingwelookathowcellsusemembrane
proteins to act cooperatively to achieve some of the basic steps of
division. Mitosis, for instance, contains many steps, including stages
ofthecellcycle.Geneticsignalsareresponsibleforthesestagesthat
are kept within the complete genome, which for
Homo sapiens
is
3.4
×
10
9
base pairs (bp) long. However, E and H fields play an
important role in adjunct (Fig. 5.4).
A numerical study of protein diffusion within the plasma
membrane of a cell exposed to a static E field demonstrates the
mechanism for a single cell. A finite-difference method was used
to mathematically model the equations of membrane diffusion
proposed by Jaffe and Nuccitelli (1977) and Poo (1981). A
computerprogramwasdevelopedandusedtocomparetheorywith
experiment. Several runs were performed varying the cell radius
(10-100
μ
m), exposure level (100-1,000 V m
−
1
) and various other
parameters, including the diffusion constant. Next, the diffusion
constant was matched to the time to reach electrophoretic equilib-
rium observed by Poo after exposure of
Xenopus
myotomal cells.
The numerical results compare reasonably well with experimental
time-sequenceasymmetrydataforconcanavalinreceptorsreported
