■ Jonathan Sarfati
ALL LIVING creatures contain incredible machines, as well as the ‘instruction manual’ to build them. This manual
comprises sequences of chemical ‘letters’
(nucleotides) in the famous deoxyribonucleic acid (DNA) molecule, just as information in a book is written in letters on
a page.
Furthermore, these instructions are
copied to the next generation. You didn’t
really get your mother’s eyes and father’s
ears; rather, it was the instructions to
re-manufacture your mother’s eyes and
father’s ears that were copied to your
DNA (see box, p 26).
DNA’s physical dimensions pose
many problems that would need to be
solved before even the simplest life
could function. The double helix is only
about 2. 5 nanometres (one ten-millionth
of an inch) wide—too thin to be seen
with any light microscope. (A complete
turn of the helix is about 10. 5 letters
long.) But the whole DNA molecule is
extremely long: the largest human chro-
mosome, number 1, is composed of 220
million letters, and would be 85 mm ( 3. 4
in) long if stretched out fully. If all the
DNA in your cell were lined up, it would
be about 2 m ( 6–7 feet) long! These enor-
mously long, thin, sticky strands must be
packed into a microscopic cell and then
maintained without forming a mess
of tangles and knots. The cell needs
complex machines to do all this. These
machines are amazing, complex, and a
testimony to the genius of our Creator.
Unwinding the double helix
When DNA is decoded (that is, when the
information is used to create a protein),
the two strands of the double helix must
be separated. And during reproduction,
each strand is copied independently.
This requires special motors called
DNA helicases. They are ring-shaped,
with a hole for the DNA to pass through.
But, since they are motors, they also need
fuel. Helicases are powered by a ‘fuel’
called ATP, which is made by another
motor, ATP-synthase.1 Using ATP as an
energy source, a cyclic change in shape
runs around the helicase ring at about
10,000 rpm—about the speed at which a
jet engine turbine rotates. The helicase
rapidly runs along the DNA and separates the two strands at the replication
fork. 2 Then, many other machines take
care of decoding the DNA and putting
the strands back together or copying the
strands. This must run very fast, because
the DNA copying speed is 1,000 letters
per second and the helicase must stay
ahead of the copying machines.
Supercoils
DNA’s helical (coiled) shape produces
another problem that is amplified when
helicase unwinds it to separate the
strands. You can easily demonstrate the
DNA detangling motors GOD’S The topoisomerase enzymes
