Page 131 - If Darwin Had Known about DNA

Adnan Oktar

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the old strip is always combined with guanine in the new one. Adeni-
ne is always joined up with thymine, and vice versa. However, during

this matching process that takes place at such high speed, a few errors
are bound to arise. Opposite adenine in one location, for example, the
DNA polymerase may install guanine instead of thymine. Errors of this
kind can sometimes represent a lethal danger. For instance, if the sixth
amino acid in the structure of hemoglobin is replaced by another
known as valine, thread-like fibers will emerge in the protein and pre-
vent erythrocytes from moving about freely, leading to the disease
known as sickle cell anemia. 94
The chemical selectivity displayed during the matching of the bas-
es is so powerful that only one error in 100,000 bases is permitted. DNA
polymerase is very sensitive to errors. If a mistaken base matching oc-

curs, it is immediately eliminated and the correct base brought in to re-
place it. Once DNA polymerase has finished its work, a separate en-
zyme checks whether any errors remain in the newly formed DNA
strip.

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* *DNA nuclease, exceedingly sensitive to errors
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Just like an editor who corrects written texts, this enzyme identi-
fies errors in the DNA and removes the wrong letter. However, this
leaves a gap in the DNA helix. Another enzyme occupies itself with that
problem.

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* * DNA ligase, repairing breaks in the DNA
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When the DNA nuclease identifies the mistaken section and ex-
tracts it, the resulting gap in the DNA strip is repaired by an enzyme
known as DNA ligase. Thanks to the perfection obtained in this very fi-
nal stage, only one error in a billion nucleotides is permitted - a level of
error many times superior to any data system under computer control.
One error in a billion is the equivalent of making only one mistake