The cell membrane is an incredibly complex system, which is hard to analyse. This
is not only due to its complexity and the many proteins, tensions, and forces to take
into account, but also because of the cell’s incredibly small size. As such, simulations
will be used to predict the membranes’ shapes.
This behaviour is dictated by the properties of the lipids, out of which a majority
of the membrane is made[2]. To analyse this phenomenon, we used the trisurf
simulation software. In the analysis, we accounted for external forces by inducing
a pressure difference within and without the cell. The most important mechanism
was the minimization of free energy, which causes the cell to deform into the most
energy-efficient shape possible under any pressure. We disregarded the nucleus due
to the fact that erythrocytes are the most interesting cell when it comes to abnormal
shapes[13], and human erythrocytes have no nucleus.
We started by making 3 sweeps of the rigidity-pressure phase space, after which
we determined which sub-space we will analyse next, based on our results. After
3 sweeps, we found an area with sufficiently realistic and interesting results. We
analysed all of the points (membrane shapes) in this sub-space by their reduced
volume and membrane free energy. We also compared them with experimental
results and came to the conclusion that for most cells, minimization of free membrane
energy is an important process and can alone determine the final cell shape. This
is not true for cells whose membranes are significantly non-homogeneous in certain
areas, as locally the proteins will win out and affect the shape, making our model
insufficient.
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