Page 144 - Engineering in Nature

Engineering in Nature

tubule from moving away from its neighboring tubule more than a
very short distance. When the loose nexin connectors extend to the
final row, the greater movement of the dynein protein makes the
nexin connectors to contract from the micro-tubule. The tension rises
as the dynein movement continues. Since the micro-tubules are flexi-
ble, the sliding movement caused by the dynein protein in the tubule
opposite gradually turns into a bending movement.

The Micro-Hairs' Mechanical System Cannot Have
Formed by Chance
As we've seen so far, a mechanical system, all of whose parts work
interdependently, has been designed in the micro-hairs and is far
more difficult than one might imagine. All the elements in the system
must be exactly right, and all their features must be fully present,
since the slightest deficiency will harm the outcome.
In order to understand this, look at any child's moving toy. If one
of the parts that permit it to move is missing, the toy will not work.
The absence of just one of its components will reduce it to just a col-
lection of plastic and metal parts that serve no purpose.
To review, these are the parts necessary in order for the micro-hairs
to move:
Micro-tubules comprise the main structure of the hairs. They are
just as essential as walls are to a building. Were it not for the micro-tu-
bules there would be no part for the engine rod to slide over.
The engine has to be present in order for the hairs, and therefore
the micro-tubules, to move.
The links cause neighboring tubules to move. The separation
movement is turned into a bending one, and the connectors prevent
the entire structure from falling apart.
In order for the system to move successfully, the components'

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