Recent discoveries move closer to explaining where life came from

[WIP]

Another hurdle has been cleared in the quest to explain the origins of the first life forms on Earth. One of the mysteries standing in the way of a theory of abiogenesis is that all of the plants, animals, microbes on Earth consist of proteins made of "left-handed" amino acids. Amino acid molecules can be built in two ways that are mirror images of each other, and experiments that have been done which try to simulate early earth conditions, starting with the Miller-Urey experiments almost 50 years ago, the pattern has been for an equal number of left-handed and right-handed amino acid chains to be created. So, explaining how living organisms break this symmetry has been a stumbling block for years. It's similar to the problem astrophysicists had with explaining why the universe is likely exclusively made up of matter, when particle accelerators create equal amounts of matter and antimatter. Now , with the discovery that many asteroids contain a significant higher amount of left-handed amino acids, it seems that left-hand bias originated in space, and the popular theories that organic molecules used to make the first living things has another point in its favour:

Over the last four years, the team carefully analyzed samples of meteorites with an abundance of carbon, called carbonaceous chondrites. The researchers looked for the amino acid isovaline and discovered that three types of carbonaceous meteorites had more of the left-handed version than the right-handed variety – as much as a record 18 percent more in the often-studied Murchison meteorite.

"We found more support for the idea that biological molecules, like amino acids, created in space and brought to Earth by meteorite impacts help explain why life is left-handed," said Dr. Daniel Glavin of NASA's Goddard Space Flight Center in Greenbelt, Md. "By that I mean why all known life uses only left-handed versions of amino acids to build proteins."

http://www.scientificblogging.com/news_rel..._astrobiologist

Add to this, the recent discoveries that:

1.that perishable RNA molecules, believed to have been the carriers of genetic information before the more durable DNA molecules were formed, could have survived in pools of sulphuric acid and

2. from computer modelling of the early solar system that microbes deep underground could have survived the heavy impacts that occured about four billion years ago, it seems we are getting closer to explaining the origins of life on earth.

[WIP]

An English chemist has discovered how RNA, the simplest self-replicating molecule, and an essential part of data transmission in living organisms, may have emerged on earth some 3.8 billion years ago.

John D. Sutherland has solved a problem that for 20 years has stood in the way of understanding 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.

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 very early on in the development of life on earth. If the first forms of life were based on RNA, then the issue is to explain how the first RNA molecules were formed.

For more than 20 years researchers have been working on this problem. The building blocks of RNA, known as nucleotides, each consist of a chemical base, a sugar molecule called ribose and a phosphate group. Chemists quickly found plausible natural ways for each of these constituents to form from natural chemicals. But there was no natural way for them all to join together -- until now:

from Neurologica May 25

RNA World

Our findings suggest that the prebiotic synthesis of activated pyrimidine nucleotides should be viewed as predisposed30. This predisposition would have allowed the synthesis to operate on the early Earth under geochemical conditions suitable for the assembly sequence. Although the issue of temporally separated supplies of glycolaldehyde and glyceraldehyde remains a problem, a number of situations could have arisen that would result in the conditions of heating and progressive dehydration followed by cooling, rehydration and ultraviolet irradiation.

So, Dr. Sutherland cannot determine which assembly sequence led to the formation of RNA, and got the ball rolling in making life possible; but merely finding possible pathways to the natural formation of RNA solves one of the major obstacles standing in the way of developing a theory of Abiogenesis, and discovering how life began on earth.

[Chuck U. Farlie]

I guess the creationists (like Sharkman and Betsy) would rather read the creationist propaganda sites to find out what scientists truly believe...

here is an article from the NY Times regarding this very same discovery: http://www.nytimes.com/2009/05/14/science/14rna.html?_r=2

[GostHacked]

I guess the creationists (like Sharkman and Betsy) would rather read the creationist propaganda sites to find out what scientists truly believe...

here is an article from the NY Times regarding this very same discovery: http://www.nytimes.com/2009/05/14/science/14rna.html?_r=2

And you won't find them reading (well maybe readin, but not postin) this thread.

[Chuck U. Farlie]

And you won't find them reading (well maybe readin, but not postin) this thread.

For sure, sharkman would rather believe that scientists think 'aliens did it'. He would like to think that the scientists are just as wacky if not more so than religious people, therefore justifying his irrational faith.

[WIP]

I guess the creationists (like Sharkman and Betsy) would rather read the creationist propaganda sites to find out what scientists truly believe...

I have to question whether they are actually reading their own creationist propaganda! If they were, they should be better informed, and able to expand on creationist and biblical literalist arguments. I've learned most of what I know about the creationist/ID movement from proponents such as a retired chemical engineer who used to post frequently on another forum, and would answer challenges to Behe's Irreducible Complexity, and Dembski's information theory that he claims can detect "intelligent design" from normal evolutionary change. Not that it makes the case for ID any more likely, but it's at least worth discussing it with someone who understands creationism, rather than someone who is just cutting and pasting from creationist sites, and doesn't appear to have even bothered to read the articles.

here is an article from the NY Times regarding this very same discovery: http://www.nytimes.com/2009/05/14/science/14rna.html?_r=2

Thanks for that one. I heard the story on the "Skeptics Guide to the Universe" podcast, and show host - Stephen Novella, mentioned that he posted the blog entry on his Neurologica blog. At the time, I couldn't find anything else about the story, except for the published research report that I don't have access to.