Friday, December 22, 2006

Where do plants come from?

We've been discussing in class a bit how we as a society are able to genetically engineer organisms - a technology that has taken hold over the past 30 years or so. But the natural world has been genetically engineering for millenia - not with anything technological or with that high a success rate, but effective nonetheless. We've mentioned earlier in the year how chloroplasts and mitochondria are believed to have evolved from prokaryotes that were engulfed by larger single-celled organisms - a process called endosymbiosis. Quite an amazing feat - esssentially harnessing the genetic power of one organism to help you survive. It was long believed that the evolution of algae and plants all stemmed from a single endosymbiotic event and that all chloroplasts share a common ancestor some 500 million years ago. But new research has shown that this may not be the case. By sequencing and comparing the genomes (full genetic makeup) of various chloroplasts (remember that chloroplasts and mitochondria have their own DNA) researchers have discovered that there were likely at least two independent endosymiotic events that lead to chloroplasts. This has many implications, including the idea that if this sort of thing can happen twice, why not more. And if it has happened more than once, what does this mean about the origin and evolution of the various photosynthetic organisms around today?

As a side note, this article/research is a good example of a branch of biology that studies the very early branches of the tree of life - basically delving back 100s of millions of years to examine how life emerged. Interesting, but difficult work.

Delving Into Chloroplasts' Past

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