New ideas in genetics


in Daily updates, Science

Adobe building, Ottawa

The high school biology version of genetics we all learned seems to be faring increasingly poorly, though that is no real surprise. The first actual human genome was sequenced recently. It belongs to J. Craig Venter, founder of Celera Genomics: the private firm that competed with the Human Genome Project to first map the human genome. Both groups used genetic material from multiple subjects and used mathematical tools that may have underplayed the level of genetic diversity that exists in human DNA.

Meanwhile, RNA is getting a lot more attention.

Some half-related earlier posts: the Global Ocean Sampling Expedition and the Human Microbiome Project.

{ 4 comments… read them below or add one }

Tom September 5, 2007 at 9:39 am

Have they figured out what ‘junk’ DNA does yet?

You have to admire the hubris there: we don’t understand this stuff, so it’s ‘junk.’

Tom September 5, 2007 at 9:51 am

All UK ‘must be on DNA database’

The whole population and every UK visitor should be added to the national DNA database, a senior judge has said.

Hilary September 7, 2007 at 2:53 am

there was much talk of all this on cbc today

. October 8, 2012 at 12:52 pm

Now ENCODE has shown that fully three-quarters of the genome is transcribed into RNA at some stage in at least one of the body’s different types of cell. Some transcripts are whittled down more or less immediately, but 62% of the genome can end up in the form of a transcript that looks stable. There is a sense in which these transcripts are the basic constituents of the genome—its atoms, if you like. The transcripts which are associated with genes describing proteins are just one type among many.

All this RNA has a wide variety of uses. It regulates what genes actually make protein and how much is made in all sorts of complicated ways; some transcripts are millions of times more common than others. Even ENCODE has not been able to catalogue all of this diversity, but it has made headway in clarifying what to look for.

Whereas 62% of the genome may be turned into finished transcripts in some cell or other, only about 22% of the DNA ends up in such transcripts in the typical cell. This is because of molecular switches that turn parts of the genome on and off depending on what the cell in question is up to. Such switches are as worthy of their place in the parts list as the locations of particular regions that code for proteins. They are, though, harder to find—and, it turns out, much more numerous.

That you need a profusion of such switches to get the right pattern of genes turned on and off in a given cell at a given time is obvious. But the scale of the regulatory system has taken even some of its cartographers by surprise. Ewan Birney of the European Bioinformatics Institute, who was the lead co-ordinator of ENCODE’s data-analysis team, says he was shocked when he realised that the genome’s 20,000-odd protein-coding genes are controlled by some 4m switches.

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