By NICHOLAS WADE
Published: November 30, 2009
Molecular biology for years meant breaking down living cells to their smallest component parts, the genes and proteins that govern what a cell does. But a list of parts tells only so much. To understand how living cells really work, biologists are now trying to visualize how the parts are assembled into operational units.
A team of European scientists has chosen one of the smallest known bacteria, called Mycoplasma pneumoniae, as a test-bed for trying to integrate all the bottom-up knowledge about an organism into a full understanding of how it actually works. The microbe causes a form of bacterial pneumonia and has shed so many functions from its stripped down genome that it can survive only as a parasite on other cells.
The European findings so far, reported in the current Science, are that the bacterium is a collection of some 200 specialized protein machines.
The machines are composed of individual proteins, which recognize each other and assemble into complexes. Some of the machines make copies of the genes embodied in the DNA of the bacterium’s genome. Others, called ribosomes, synthesize proteins according to the genetic instructions they receive. Another class, called chaperones, make sure the new proteins fold up correctly. Then there are processing machines in which each component carries out one step of a multistage chemical process.
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In a commentary in Science, two biologists at the University of Arizona, Howard Ochman and Rahul Raghavan, say the European work shows that “there is no such thing as a ‘simple’ bacterium,” given how complex even this miniature member of the bacterial world has turned out to be.
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NOTA CAUSTICANTE DESTE BLOGGER:
Se a teoria da evolução através da seleção natural não explica a origem da complexidade irredutível de um 'simples' flagelo bacteriano, como pode explicar a complexidade e diversidade das coisas bióticas 'superiores'???
Seleção natural? Nem a pau, Juvenal! É 100% design inteligente!!! Processo télico.
