The story we have been told by creationists and neo-Panglossian scientists is that most if not all noncoding DNA is functional and that this fact has been obscured by long neglect in the scientific community of the potential importance of noncoding elements. In particular, the “junk DNA” and “selfish DNA” ideas put forth in the 1970s and 1980s are suggested to have stifled interest in the possible biological and medical importance of noncoding sequences, which have long been dismissed as irrelevant. The question is, did the scientific community turn its back on researchers interested in the roles of noncoding elements after 1980?
1983 Nobel Prize in Physiology or Medicine
to Barbara McClintockFor her discovery of
mobile genetic elements
Barbara McClintock discovered mobile genetic elements in plants more than 30 years ago. The discovery was made at a time when the genetic code and the structure of the DNA double helix were not yet known. It is only during the last ten years that the biological and medical significance of mobile genetic elements has become apparent. This type of element has now been found in microorganisms, insects, animals and man, and has been demonstrated to have important functions.
Such elements were also found to have an important function in the ability of unicellular parasites (trypanosomes) to change their surface properties, thereby avoiding the immune response of the host organism. Recombination of DNA segments proved to be an essential factor in the ability of lymphoid cells to produce a seemingly infinite number of different antibodies to foreign substances. In recent years, evidence has accumulated that transposition of genes or incomplete genes are involved in the transformation of normal cells into tumour cells. Thus, genes controlling cell growth have been found to undergo translocation from chromosome to another during cancerogenesis. The initial discovery of mobile genetic elements by Barbara McClintock is of great medical and biological significance. It has also resulted in new perspectives on how genes are formed and how they change during evolution.
1993 Nobel Prize in Physiology or Medicine
to Richard J. Roberts and Phillip A. Sharp
For their discovery of split genes
[introns and exons]
Roberts’ and Sharp’s discovery has changed our view on how genes in higher organisms develop during evolution. The discovery also led to the prediction of a new genetic process, namely that of splicing, which is essential for expressing the genetic information. The discovery of split genes has been of fundamental importance for today’s basic research in biology, as well as for more medically oriented research concerning the development of cancer and other diseases.
As a consequence of the discovery that genes are often split, it seems likely that higher organisms in addition to undergoing mutations may utilize another mechanism to speed up evolution: rearrangement (or shuffling) of gene segments to new functional units. This can take place in the germ cells through crossing-over during pairing of chromosomes. This hypothesis seems even more attractive following the discovery that individual exons in several cases correspond to building modules in proteins, so-called domains, to which specific functions can be attributed. An exon in the genome would thus correspond to a particular subfunction in the protein and the rearrangement of exons could result in a new combination of subfunctions in a protein. This kind of process could drive evolution considerably by rearranging modules with specific functions.
Part of the Quotes of interest series.