Why are there 23 pairs of chromosomes?

Nick Giannoukakis b2d6 at musicb.mcgill.ca
Sat Jul 15 14:47:01 EST 1995

Hello Jared,

Although we use the term "junk DNA" quite frequently, it is becoming apparent that these noncoding,
intervening sequences may actually have something to do with the organisation of chromosomes, 
topologically, within the nucleus. For instance, it may be that certain DNA-binding molecules interact
with some sort of motif (sequence or 3D) within these regions, and mediate their attachment to the nuclear
matrix (akin to matrix arttachment regions). It could be that these areas are important during crossover
events as well. I can't remember the particular article, but there is preliminary evidence in support of these

On a related vein, has anyone read Gunter Blobel's gene gating hypothesis? It was published in 1985
in PNAS (I can't remember the volume offhand..), and he proposes that the 3D structure of the genome 
changes throughout development and that this may have some effect on gene transcription. Could it be 
that this "junk DNA" is fundamentally important for the topological dynamism (assuming his hypothesis is
correct) of the genome of an organism during development (or disease, for that matter!!) ?


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