Junk DNA

Glenn Morton (grmorton@waymark.net)
Sat, 20 Dec 1997 21:55:53 -0600

As part of my education about the genetic system ( for which I thank many
people who took time to point me to several references) I ran into the
following very interesting fact. Many vertebrate genomes have large
sections of "junk" DNA which apparently have no purpose. Some small
sections of it have been found to have some function, but in general therre
is none. Anderson and Kurland cite a fish which has most of the junk DNA

"In addition, the sizes of many eukaryotic genomes are greatly
augmented, if not dominated, by sequences of varying degrees of
repetitiveness but with no known functions. It is worth noting
that there is a fish clade that has, in the course of its
evolution, discarded 90% of the noncoding sequences that are
prominent in most other vertebrate genomes. It seems likely
from this one example that most eukaryotic genomic sequences have
no function, though they are not easily purged."~S. G. E.
Andersson and C. G. Kurland, "Genomic Evolution Drives the
Evolution of the Translation System," Biochem. Cell Biol.,
73(1995):775-787, p. 776

Obviously if one complex organism doesn't need the stuff, then it can't have
a very important function. So why would God create orgainisms with this
much useless "design"?

Secondly, the same article cited the fact that proteins are not quite so
sensitive to mutations as anti-evolutionists would have us believe.
Andersson and Kurland write:

"In fact, bacteria growing in normal laboratory media are
relatively insensitive to increased errors of gene expression
generated by mutant translation components, antibiotics, or
combinations of both. For example, a quadrupling of the
translational error frequency from about 5 errors/10000 codons to
2 errors/1000 codons has been studied. For proteins with a mean
chain lenght of 300 amino acids, this corresponds to a decreas
from nearly 90% error-free proteins to close to 50% error-free
proteins. Nevertheless, the growth rate of the error-prone
bacterial population decreases only by 30% compared with that of
the wild-type bacteria.
"Likewise, individual proteins are typically not
particularly fragile rather, their structures and functions are
robuts in response to amino acid substitutions generated by
mutations in cells or by molecular geneticists in laboratories.
For the overwhelming majority of the thousands of substitutions
that have been studied to date, the response to a single amino
acid substitution in a protein is much less than a halving of its
activity. Although none of these experimental manipulations is
identical with a codon reassignment, they do suggest that protein
populations are sufficiently robust to survive the insults
associated with individual codon reassignments."~S. G. E.
Andersson and C. G. Kurland, "Genomic Evolution Drives the
Evolution of the Translation System," Biochem. Cell Biol.,
73(1995):775-787, p. 776

Thus when Gish claims,

"The highly specific biological activity of each protein is due to
the precise way the amino acids are arranged, just as the
information conveyed by this sentience is determined by the precise
sequence of the 190 letters found in it."~Duane Gish, "The Origin
of Life," Proc. First Inter. Conf. on Creationism, Vol. 1,
(Pittsburg: Creation Science Fellowship, 1986), p.62

he is wrong.


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