Page 74 - The Miracle in the Cell Membrane

The Miracle in the Cell Membrane

mechan i cal, but is a very com plex proc ess that alters in
accord ance with con di tions.
The evo lu tion ist biol o gist Hoimar von Ditfurth refers
to this selec tion mech a nism with great amaze ment:

. . . we are look ing at . . . a kind of molec u lar nerve fence with
a far great er abil i ty than any porous web or fil ter. As we can
observe from siev ing sand, mechan i cal sieves do not per mit
bod ies whose cir cum fer ence is great er than a cer tain level to
pass through. Those with a large cir cum fer ence are caught in
the sieve, while small er ones pass through. Clearly, such a
sim ple "dis tinc tion" that divides mat ter into only two class es
accord ing to size, while mak ing no dis tinc tion among those
par ti cles above and below the bench mark, will do the cell no
good what so ev er. Because in order to grow and devel op, the
cell needs a wide range of mol e cu les. And in order to sur vive
some of the mol e cu les it has to leave "out side" may be as large
or small, or even the same size, as those it lets in.
Thus a non-mechan i cal, bio log i cal nerve mem brane is able to
flaw less ly per form such a proc ess of selec tion and elim i na tion.
This mem brane dis tin guish es between sub stan ces accord ing
to their type, rath er than their size. To put it anoth er way, it
selects accord ing to qual i ta tive cri te ria rath er than quan ti ta -
tive ones. This is an aston ish ing, mind-bog gling abil i ty. . . . 24
That such a del i cate struc ture, invis i ble to the naked
eye, should pos sess such a selec tion mech a nism can not
be account ed for in terms of blind coin ci den ces. The cell's
selec tion mech a nism, which we shall detail in later chap -
ters, requires intel li gence and aware ness. It is cer tain ly
impos si ble for cells to feel such a respon si bil i ty of their

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