Re: Junk DNA again

From: Jim Armstrong (jarmstro@qwest.net)
Date: Fri May 23 2003 - 16:15:49 EDT

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    Most if not all of the discussion here sort of seems to tacitly assume
    that the DNA is laid out in a long straight ladder configuration.
    However I seem to recall that the physical contours of that ladder
    (folds, structural proximities, etc.) also may have significance. As I
    recall, that led one genome worker I know to be hesitant about the
    descriptor "junk DNA" because the repetitive DNA sequences may actually
    have value in determining spacings or otherwise physically configuring
    the overall shape of the DNA material, thereby affecting how some of the
    genetic structures may or may not be brought into influential proximity
    with one another.

    Jim Armstrong.

    bivalve wrote:

    >The latest Science has another example of purportedly junk DNA having usefulness; unfortunately for the current ID movement, it is evolutionary usefulness. Here's their summary:
    >
    >This Week in SCIENCE, Volume 300, Issue 5623,
    >dated May 23 2003
    >Putting DNA Sequences Back to Work
    >
    >Repetitive Alu sequences are part of the nonprotein coding "junk" DNA, but mutations in these sequences can form coding exons. Although this process is associated with disease in some cases, it also is a way for the genome to evolve. Lev-Maor et al. (p. 1288; see the Perspective by Makalowski)
    >have assembled a database of "exonized" Alu elements and identified the particular sequences and positions that can allow the crucial splicing to occur. They tested their proposed mechanism in a mini-gene construct and found that a single mutation can result in exonization.
    >
    >
    >
    >
    > Dr. David Campbell
    > Old Seashells
    > University of Alabama
    > Biodiversity & Systematics
    > Dept. Biological Sciences
    > Box 870345
    > Tuscaloosa, AL 35487-0345 USA
    > bivalve@mail.davidson.alumlink.com
    >
    >That is Uncle Joe, taken in the masonic regalia of a Grand Exalted Periwinkle of the Mystic Order of Whelks-P.G. Wodehouse, Romance at Droitgate Spa
    >
    >
    >
    >
    >
    >



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