Sunday, September 09, 2012

An important new set of publications on our biology

Our understanding of evolution stems from the work of Darwin and Mendel in the 19th century. I associate the evolutionary synthesis with the work of Julian Huxley in the first half of the 20th century. Watson and Crick described the structure of DNA in 1953. The human genome -- with the 3 billion chemical pairs which define the 20,000 to 25,000 genes on the 23 pairs of human chromosomes -- was first published between 2000 and 2003.

One of the surprises from the Human Genome Project was that so little of the DNA seemed actually to be part of the genes. It had previously been thought that DNA in genes was transcribed into RNA which in turn was transcribed into proteins, with relatively little of the genome involved in turning genes on and off. It turned out that only a relatively small part of the genome is actually transcribed into proteins in that way.

According to The Economist, a new major step has been taken in the scientific understanding of how our DNA works. ENCODE, the Encyclopedia of DNA Elements, has been published by a consortium —442 members in 32 institutes around the world. It has used the increasingly impressive tools available for sequencing genomes to mount a systematic analysis of 147 different types of human cell.

The new research concludes that 62% of the genome may be turned into finished transcripts in some cell or other, but only about 22% of the DNA ends up in such transcripts in the typical cell. Surprisingly, the genome’s 20,000-odd protein-coding genes appear to be controlled by some 4 million switches that are also encoded in the genome.

There have been advances in medicine along the way. We now take it as obvious that some diseases are genetic and have learned about some of the mutations that cause specific diseases. Indeed, we have learned that many of the mutations that cause disease are de novo, where genetically normal parents give birth to a child with a genetic defect. The new research is likely to trigger still more research, bringing still greater understanding of the genetic basis of our cell behavior. Eventually, there will be new meds to prevent or treat disease.

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