emc wrote:bystander, "I don't know" is a good answer... it way out weighs anything in my "know" category. Your point is well received.
"One might be capable of making an intelligent guess" is a better answer, IMO.
------------------------------------
The Drake Equation for how many intelligent,
communicating civilizations there are in our galaxy.:
http://www.activemind.com/Mysterious/To ... ation.html
------------------------------------
LIFE, n. : In a general sense, that state of animals and plants, or of an organized being, in which its natural functions and motions are performed, or in which its organs are capable of performing their functions. [Webster Dictionary (1828 edition)]
................................
Martian rovers Spirit & Opportunity are communicating & are capable of performing their functions.
Are Spirit & Opportunity "alive" in some sense?
http://marsrovers.jpl.nasa.gov/mission/ ... _maps.html
------------------------------------
From Primordial Soup to the Prebiotic Beach
An [October, 1996] interview with exobiology pioneer, Dr. Stanley L. Miller, University of California San Diego
http://www.accessexcellence.org/WN/NM/miller.html
<<Q:Some 4.6 billion years ago the planet was a lifeless rock, a billion years later it was teeming with early forms of life. Where is the dividing line between pre-biotic and biotic Earth and how is this determined?
Dr. Miller: We start with several factors. One, the Earth is fairly reliably dated to 4.55 billion years. The earliest evidence for life was 3.5 billion years based on findings at the Apex formation in Western Australia. A new discovery reported in the journal Nature indicates evidence for life some 300 million years before that. We presume there was life earlier, but there is no evidence beyond that point.
....................................
Q:So while these are potential sources of organic compounds they are not essential for the creation of life on Earth?
Dr. Miller: As long as you have those basic chemicals and a reducing atmosphere, you have everything you need. People often say maybe some of the special compounds came in from space, but they never say which ones. If you can make these chemicals in the conditions of cosmic dust or a meteorite, I presume you could also make them on the Earth. I think the idea that you need some special unnamed compound from space is hard to support. You have to consider separately the contributions of meteors, dust and comets. The amount of useful compounds you are going to get from meteorites is very small. The dust and comets may provide a little more. Comets contain a lot of hydrogen cyanide, a compound central to prebiotic synthesis of amino acids as well as purines. Some HCN came into the atmosphere from comets. Whether it survived impact, and how much, are open to discussion. I'm skeptical that you are going to get more than a few percent of organic compounds from comets and dust. It ultimately doesn't make much difference where it comes from. I happen to think prebiotic synthesis happened on the Earth, but I admit I could be wrong. There is another part of the story. In 1969 a carbonaceous meteorite fell in Murchison Australia. It turned out the meteorite had high concentrations of amino acids, about 100 ppm, and they were the same kind of amino acids you get in prebiotic experiments like mine. This discovery made it plausible that similar processes could have happened on primitive Earth, on an asteroid, or for that matter, anywhere else the proper conditions exist.
http://www.fredparker.com/mp00402.htm
....................................
Q: Tell us about your recent work and the lagoon idea.
Dr. Miller: The primitive Earth had big oceans, but it also had lakes, lagoons and beaches. Our hypothesis is that the conditions may have been ideal on these beaches or drying lagoons for prebiotic reactions to occur, for the simple reason that the chemicals were more concentrated in these sites than in the middle of the ocean. Our most recent research tackled the problem of making pyrimidines- uracil and cytosine, in prebiotic conditions. For some reason it just doesn't work very well under dilute conditions. We showed that it works like a charm once you get things concentrated and dry it out a bit. This changed my outlook on where to start looking for prebiotic reactions. Another example is our work with co-enzyme A. The business end of co-enzyme A is called pantetheine. We showed you could make this under these kind of pre-biotic "dry beach" conditions. We found that you didn't need it to be very hot, you can make it at 40 degrees C. This indicates the ease with which some of this chemistry can take place.
San Francisco Chronicle
Giant step toward artificial life
Sabin Russell, Chronicle Medical Writer
http://www.sfgate.com/cgi-bin/article.c ... NUKKE4.DTL
.
(01-24) 12:13 PST SAN FRANCISCO -- <<American scientists have built from scratch a synthetic chromosome containing all the genetic material needed to produce a primitive bacterium - a giant step toward the creation of artificial life.
.
The feat is described in an online edition of the journal Science released Thursday by researchers at the J. Craig Venter Institute in Rockville, Md. Venter is the Bay Area-born maverick whose laboratory techniques in the late 1990s led to the speedy decoding of the human genome, the entire set of genetic instructions for making a person.
.
Now, a team led by Dr. Hamilton Smith, director of the Venter Institute's Synthetic Biology Group, has manufactured from laboratory chemicals a ring of DNA containing all the genes of Mycoplasma genitalium - the tiniest bacteria ever found.
.
That means the team is tantalizingly close to creating an artificial form of life that could replicate itself using these machine-made genes. The plan is to slip the synthetic chromosome inside the microscopic skin of one of the Mycoplasma bacterium, replacing its natural genome with the machine-made one and sparking the creature into a life form that can reproduce itself.
.
"If we'd done that already, we'd be letting people know. That's not the kind of secret you keep," Venter said by telephone from Davos, Switzerland. "But I am virtually certain it will happen this year."
.
The work is not merely a demonstration of laboratory finesse, Venter insisted, but a step toward development of technologies that could grow fuel in bacterial vats and speed cures for diseases. "It puts a lot of power in the hands of humans," he said. And there is the matter of bragging rights of mythological proportions. Mere mortals have yet to lay claim to creating life.
.
In August, the Venter Institute team reported in the journal Science that they had performed a successful transplant of a natural genome by removing the chromosome from one Mycoplasma species and implanting it into another, which began replicating copies of the first species. Venter said there are still several technical hurdles to pass before a similar procedure could work with the synthetic chromosome.
.
Although such a creature might pass for artificial life, it would not be entirely synthetic because only the genes would be machine made. In addition, scientists who work with much smaller viruses can now, almost routinely in elite laboratories, produce living viruses using laboratory-designed genes.
.
What is different here is that the bacterial genome Venter's lab has fabricated is about 20 times larger than the longest viral genome ever made by machines. Consisting of sequences of paired chemicals represented by the letters A, C, T and G, a computer printout of the Mycoplasma chromosome fills 147 single-spaced pages of paper. The actual synthetic chromosome, Venter said, is "the largest molecule ever built by humans, by a large margin."
.
And unlike human-made viruses, a synthetic bacterium would be able to make copies of itself by cell division. Viruses must hijack the machinery of living cells to replicate, a reason many biologists consider them infectious agents rather than living things.
.
Once the laboratory produces living, replicating bacteria using this artificial chromosome, Venter scientists plan to strip away genes systematically, to find how few are truly necessary to sustain life.>>
--------------------------------------------
[quote="emc"]bystander, "I don't know" is a good answer... it way out weighs anything in my "know" category. Your point is well received.[/quote]
"One might be capable of making an intelligent guess" is a better answer, IMO.
------------------------------------
The Drake Equation for how many intelligent,
communicating civilizations there are in our galaxy.:
http://www.activemind.com/Mysterious/Topics/SETI/drake_equation.html
------------------------------------
LIFE, n. : In a general sense, that state of animals and plants, or of an organized being, in which its natural functions and motions are performed, or in which its organs are capable of performing their functions. [Webster Dictionary (1828 edition)]
................................
Martian rovers Spirit & Opportunity are communicating & are capable of performing their functions.
Are Spirit & Opportunity "alive" in some sense?
http://marsrovers.jpl.nasa.gov/mission/traverse_maps.html
------------------------------------
[quote]From Primordial Soup to the Prebiotic Beach
An [October, 1996] interview with exobiology pioneer, Dr. Stanley L. Miller, University of California San Diego
http://www.accessexcellence.org/WN/NM/miller.html
<<Q:Some 4.6 billion years ago the planet was a lifeless rock, a billion years later it was teeming with early forms of life. Where is the dividing line between pre-biotic and biotic Earth and how is this determined?
Dr. Miller: We start with several factors. One, the Earth is fairly reliably dated to 4.55 billion years. The earliest evidence for life was 3.5 billion years based on findings at the Apex formation in Western Australia. A new discovery reported in the journal Nature indicates evidence for life some 300 million years before that. We presume there was life earlier, but there is no evidence beyond that point.
....................................
Q:So while these are potential sources of organic compounds they are not essential for the creation of life on Earth?
Dr. Miller: As long as you have those basic chemicals and a reducing atmosphere, you have everything you need. People often say maybe some of the special compounds came in from space, but they never say which ones. If you can make these chemicals in the conditions of cosmic dust or a meteorite, I presume you could also make them on the Earth. I think the idea that you need some special unnamed compound from space is hard to support. You have to consider separately the contributions of meteors, dust and comets. The amount of useful compounds you are going to get from meteorites is very small. The dust and comets may provide a little more. Comets contain a lot of hydrogen cyanide, a compound central to prebiotic synthesis of amino acids as well as purines. Some HCN came into the atmosphere from comets. Whether it survived impact, and how much, are open to discussion. I'm skeptical that you are going to get more than a few percent of organic compounds from comets and dust. It ultimately doesn't make much difference where it comes from. I happen to think prebiotic synthesis happened on the Earth, but I admit I could be wrong. There is another part of the story. In 1969 a carbonaceous meteorite fell in Murchison Australia. It turned out the meteorite had high concentrations of amino acids, about 100 ppm, and they were the same kind of amino acids you get in prebiotic experiments like mine. This discovery made it plausible that similar processes could have happened on primitive Earth, on an asteroid, or for that matter, anywhere else the proper conditions exist.
http://www.fredparker.com/mp00402.htm
....................................
Q: Tell us about your recent work and the lagoon idea.
Dr. Miller: The primitive Earth had big oceans, but it also had lakes, lagoons and beaches. Our hypothesis is that the conditions may have been ideal on these beaches or drying lagoons for prebiotic reactions to occur, for the simple reason that the chemicals were more concentrated in these sites than in the middle of the ocean. Our most recent research tackled the problem of making pyrimidines- uracil and cytosine, in prebiotic conditions. For some reason it just doesn't work very well under dilute conditions. We showed that it works like a charm once you get things concentrated and dry it out a bit. This changed my outlook on where to start looking for prebiotic reactions. Another example is our work with co-enzyme A. The business end of co-enzyme A is called pantetheine. We showed you could make this under these kind of pre-biotic "dry beach" conditions. We found that you didn't need it to be very hot, you can make it at 40 degrees C. This indicates the ease with which some of this chemistry can take place.[/quote]
[quote]San Francisco Chronicle
Giant step toward artificial life
Sabin Russell, Chronicle Medical Writer
http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2008/01/25/MNPNUKKE4.DTL
.
(01-24) 12:13 PST SAN FRANCISCO -- <<American scientists have built from scratch a synthetic chromosome containing all the genetic material needed to produce a primitive bacterium - a giant step toward the creation of artificial life.
.
The feat is described in an online edition of the journal Science released Thursday by researchers at the J. Craig Venter Institute in Rockville, Md. Venter is the Bay Area-born maverick whose laboratory techniques in the late 1990s led to the speedy decoding of the human genome, the entire set of genetic instructions for making a person.
.
Now, a team led by Dr. Hamilton Smith, director of the Venter Institute's Synthetic Biology Group, has manufactured from laboratory chemicals a ring of DNA containing all the genes of Mycoplasma genitalium - the tiniest bacteria ever found.
.
That means the team is tantalizingly close to creating an artificial form of life that could replicate itself using these machine-made genes. The plan is to slip the synthetic chromosome inside the microscopic skin of one of the Mycoplasma bacterium, replacing its natural genome with the machine-made one and sparking the creature into a life form that can reproduce itself.
.
"If we'd done that already, we'd be letting people know. That's not the kind of secret you keep," Venter said by telephone from Davos, Switzerland. "But I am virtually certain it will happen this year."
.
The work is not merely a demonstration of laboratory finesse, Venter insisted, but a step toward development of technologies that could grow fuel in bacterial vats and speed cures for diseases. "It puts a lot of power in the hands of humans," he said. And there is the matter of bragging rights of mythological proportions. Mere mortals have yet to lay claim to creating life.
.
In August, the Venter Institute team reported in the journal Science that they had performed a successful transplant of a natural genome by removing the chromosome from one Mycoplasma species and implanting it into another, which began replicating copies of the first species. Venter said there are still several technical hurdles to pass before a similar procedure could work with the synthetic chromosome.
.
Although such a creature might pass for artificial life, it would not be entirely synthetic because only the genes would be machine made. In addition, scientists who work with much smaller viruses can now, almost routinely in elite laboratories, produce living viruses using laboratory-designed genes.
.
What is different here is that the bacterial genome Venter's lab has fabricated is about 20 times larger than the longest viral genome ever made by machines. Consisting of sequences of paired chemicals represented by the letters A, C, T and G, a computer printout of the Mycoplasma chromosome fills 147 single-spaced pages of paper. The actual synthetic chromosome, Venter said, is "the largest molecule ever built by humans, by a large margin."
.
And unlike human-made viruses, a synthetic bacterium would be able to make copies of itself by cell division. Viruses must hijack the machinery of living cells to replicate, a reason many biologists consider them infectious agents rather than living things.
.
Once the laboratory produces living, replicating bacteria using this artificial chromosome, Venter scientists plan to strip away genes systematically, to find how few are truly necessary to sustain life.>>[/quote]
--------------------------------------------