Posts tagged: genome

Are You Special?

Are you special?  Are you really unique, or a merely a unique assemblage of identical elements?  Identical twins are thought to be just that-identical.  Since they share the same DNA, there should be no physical or mental differences.  Strangely, this is not the case.  Identical twins do not have identical personality profiles.  Their physical resemblance is like a mirror when young, but subtle differences emerge with age.  Identical twins are not known to die on the same day, though born at the same time.  What could account for the increased differentiation over time?

At least one mechanism has been found to account for the observed disparity.  This biochemical mechanism may also explain wide physical and mental variations within any given family.  The initial groundbreaking work was performed by Dr. Barbara McClintock.  Even before the double helix model of DNA was discovered, Dr. McClintock revealed that regions of corn DNA could migrate to new areas of the DNA strand.  In effect, a unique corn genome was produced.  Identical strands of corn DNA produced seeds of different colors.  Her discovery added a page to the work of Gregor Mendel-the father of genetic inheritance.  Further discoveries reveal that this “jumping gene” mechanism is not unique to corn, or plants in general.  It occurs in many organisms-including humans.

The “jumping gene” mechanism in higher animals appears to differ from that of plants.  The plant DNA actually moves from one region of the genome to another; activating or suppressing protein transcription in that region.  The animal DNA appears to make a copy of the specific region, and reinserts itself in another area of the genome-just like plants.  The difference between plants and animals appears to be whether the region of DNA is removed or copied.

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The favorable aspect of “jumping genes” is its ability to assist the organism in adjusting to a changing environment.  The unfavorable aspect is that a new combination of DNA elements may be harmful to the organism.  An unusual number of these unique “jumping gene” sequences of DNA have been discovered in the frontal cortex of schizophrenics.  These unique sequences of DNA are also increased in autism and Rett’s syndrome-a severe neurodevelopmental disorder.

Even though the “jumping gene” mechanism may have accelerated human evolution, it may also engender a greater incidence of dysfunction and breakdown.  “Jumping genes” may have allowed the human lamp to burn ever brighter, yet rendered the flame less than reliable.  So, every human is special-right down to their DNA.  The dilemma arises in regard to the functional outcome of the genetic alterations.  Does a unique trait increase adaptation to the environment, or render the organism less than functional?  It is good to be special, but perhaps it is not good to be too special.