Posts tagged ‘life’

Life a fundamental consequence of organic chemistry

He has solved a problem that for 20 years has thwarted researchers trying to understand the origin of life — how the building blocks of RNA, called nucleotides, could have spontaneously assembled themselves in the conditions of the primitive earth. The discovery, if correct, should set researchers on the right track to solving many other mysteries about the origin of life. It will also mean that for the first time a plausible explanation exists for how an information-carrying biological molecule could have emerged through natural processes from chemicals on the primitive earth

Scientists have long suspected that the first forms of life carried their biological information not in DNA but in RNA, its close chemical cousin. Though DNA is better known because of its storage of genetic information, RNA performs many of the trickiest operations in living cells. RNA seems to have delegated the chore of data storage to the chemically more stable DNA eons ago. If the first forms of life were based on RNA, then the issue is to explain how the first RNA molecules were formed

The spontaneous appearance of such nucleotides on the primitive earth “would have been a near miracle,” two leading researchers, Gerald Joyce and Leslie Orgel, wrote in 1999. Others were so despairing that they believed some other molecule must have preceded RNA and started looking for a pre-RNA world.

The miracle seems now to have been explained.

“My assumption is that we are here on this planet as a fundamental consequence of organic chemistry,” Dr. Sutherland said. “So it must be chemistry that wants to work.”

via Chemist Shows How RNA Can Be the Starting Point for Life – NYTimes.com.

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May 13, 2009 at 5:53 pm Leave a comment

Viral missing link

Viruses are an interesting form of life, if you can consider them life at all.  This research adds some more data to our understanding of life.

Some researchers called it a “missing link” that blurred the boundaries between viruses and living cells, between living and dead.

Despite all this attention the mimivirus’ physical structure remained a blur. Like other viruses, it was made from DNA surrounded by a protein coat called a capsid, but long fibers on the capsid’s surface made it difficult to see the mimivirus’ underlying structure.

To get a clearer picture, French and American biochemists dissolved mimivirus fibers with enzymes, then used an electron microscope to take thousands of pictures that were eventually combined into a three-dimensional structure. The results, published recently in Public Library of Science Biology, provide further evidence that mimiviruses straddle the boundary between virus and bacteria.

Whereas the DNA of other viruses are tightly wrapped, there’s a large gap between the mimivirus genome and its capsid. In some ways, this resembles less the structure of a virus than of a living cell, in which DNA is contained in a nucleus, which in turn floats in cell-wall-enclosed cytoplasm.

“The new structural finds, along with previous genetic and morphological work, confirm that mimivirus is an odd mix of genes and parts found in viruses, bacteria and even eukaryotes, the organisms that sequester their DNA in a nucleus,” write the researchers.

What does this mean, then, for the mimivirus’ official status, which has caused some researchers to call for a redefinition of virus?

via Viral Missing Link Caught on Film | Wired Science.

May 5, 2009 at 2:32 pm Leave a comment


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