May I make a belated, and rather different contribution to the recent
discussion about the nature and purpose of "junk" DNA ? There is the
possibility that the purpose of "junk" DNA is to enable long lengths of
like-sequence, repetitive DNA to recognise each other, which could explain
why it is needed in such long lengths. (I suspect we might only call it
"junk" DNA because we haven't yet agreed a secure purpose for it.)
Long lengths of repetitive DNA capable of recognising the same, or closely
similar, repeat sequences could assist in the formation of the "30 nm" fibre
of compacted nucleosomes, and in the assembly of centromeres.
In addition, prior to cell division, the pairing of like chromosomes could
be facilitated before separation during mitosis or meiosis, for example.
The 13 pairs of human chromosomes would each need closely similar repeat
sequences (each with the other), and these would need to be rather different
from the repeat sequences in the other pairs. Perhaps subscribers know the
repeat
sequences of all of the human chromosomes ?
The unique pairing of Watson-Crick base pairs, AT with AT and GC with GC,
was described first by Loewdin in 1963, as far as I am aware. These
properties
of DNA and others are explored and developed in detail in my two books
(1,2).
In a single posting it is impossible to develop the arguments, but those
wishing to consider fresh aspects of the behaviour of DNA may care to view
the newsgroup "bionet.biophysics" to which I am currently posting the second
series of DNA Structure Puzzles intended to focus attention on the wide
range of experimental data which is otherwise unexplained in the literature.
The attachments to the DNA Structure Puzzles in "bionet.biophsyics" include
sketches of how individual base pairs can themselves form pairs, as well as
a sketch of a model of DNA which facilitates such pairing.
To any interested subscribers, I could send e-mail attachments of the scheme
for pairing base pairs, and of the framework of the overall structure within
which such pairing is facilitated.
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1 Towards a New Structural Molecular Biology, by Clive Delmonte
(1991) ISBN 0 9512276 0 2
"...I find much of Delmonte's critique of other workers sound enough to
raise doubt in my mind about the bulk of the classical work in this area.
...the book was an eye-opener."
Prof. Steven Benner at Eidgenossische Technische Hochscule, Zurich
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"...the widely accepted Watson-Crick model is inadequate to explain many
important pieces of data, and in some cases defies intuitive biological and
physical logic as a predictive model..I commend you on your recognition of
inconsistencies in the story of DNA..you have the potential of changing
molecular biology."
Prof. Robert Hopkins at the School of Applied and Natural Sciences in the
University of Houston at Clear Lake, Texas
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2 Advances in AFM & STM Applied to the Nucleic Acids, by Clive
Delmonte (1997) ISBN 0 9512276 2 9, Library of Congress TX 4-856-037
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Clive Delmonte
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