THE FIRST CELL?: Scientists at Harvard Medical School have designed what they think is a reasonable model for the first cell on Earth, some 3.5 to four billion years ago.
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Modern cells are like microscopic cities: They have power plants (mitochondria), trash dumps (lysosomes), local government (the nucleus, with DNA serving as the legal charter), and many other activities going on inside their boundaries. They also have a border patrol in the form of a double-layered membrane that uses a series of protein-powered pumps, pores and channels to let nutrients in and keep other chemicals and substances out.
But, cells were very different when life began 3.5 billion to four billion years ago. Rather than small metropolises, they were more like a purse that carried instructions—consisting of just a membrane with genetic information inside. They lacked the structures and proteins that now make them tick. The question is: How then were they able to take in the nutrients necessary to survive and reproduce?
Harvard Medical School researchers report in Nature that they have built a model of what they believe the very first living cell may have looked like, which contains a strip of genetic material surrounded by a fatty membrane. The membranes of modern cells consist of a double layer of fatty acids known as phospholipids. But in designing a membrane for their cell, scientists worked with much simpler fatty acids that they believe existed on a primeval Earth, when the first cell likely formed. The key, says study co-author Jack Szostak, a Harvard geneticist, was to develop one porous enough to let in needed nutrients (such as nucleotides, the units that make up genetic material, or DNA) but strong enough to protect the genetic material inside and keep it from slipping out after replicating.
In an attempt to duplicate an early cell, scientists put fatty acids (that were likely membrane candidates) and a strip of DNA into a test tube of water. While in there, the fatty acids formed into a ring, or membrane, around the genetic segment. The researchers then added nucleotides—units of genetic material—to the test tube to determine whether they would penetrate the membrane and copy the DNA inside it. Their findings: the nucleotides did enter the cell, latch onto and replicate the DNA over 24 hours.
What scientists now must figure out, Szostak says, is how the original and copycat DNA strands separated and this early cell divided or reproduced.
"We're trying to solve a whole series of problems, step by step," he says, "and build up to replicating an evolving system."
David Deamer, a biomolecular engineer at the University of California, Santa Cruz, says he believes the team is on its way to making a prototype of a primitive cell that has "essentially all the basic properties of life."
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20 Comments
Add CommentI thought the first cells originally contained RNA without DNA...
Reply | Report Abuse | Link to thisNotice that this replication of a hypothetical "first cell" is itself a product of quite literally "intelligent design". Does no one else see the irony?
Reply | Report Abuse | Link to this>>Does no one else see the irony?
Reply | Report Abuse | Link to thisNo. Personally i dont see the point of having scientists just sitting around in a lab waiting for experiments to happen by on thier own.
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Edited by alajjana at 06/11/2008 6:40 AM
Fishy. DNA does not replicate itself. This article is not telling the whole story.
Reply | Report Abuse | Link to thisFascinating story. So.... I would like to know what practical purpose or purposes such knowledge will provide for society. Or does one need to read an abstract for that? The article states, "But cells were very different when life began 3.5 to four billion years ago." Do you have direct evidence of 3 or 4 billion year old life or is this a leap of faith?
Reply | Report Abuse | Link to thisThanks for any response.
http://www.bccmeteorites.com/NASAcert.html
> I thought the first cells originally contained RNA
Reply | Report Abuse | Link to this> without DNA...
Jury's still out on that. Both the RNA world and the "naked genie" scenario are plagued with what seem to be insuperable difficulties. This is what has lead Dr. Robert Shapiro to propose his "garbage bag" scenario ([url http://science-community.sciam.com/blog-entry/Sciam-Observations/Interactive-Publishing-Simpler-Origin-Life/300004148][/url]). It has yet to be critically examined.
>This article is not telling the whole story.
Reply | Report Abuse | Link to thisThought so: "Although no sequence-general means for the non-enzymatic replication of a genetic polymer has yet been found, we have identified a system that exhibits remarkably rapid and efficient non-enzymatic copying of an oligo-dC DNA template (Supplementary Fig. 7). We used this system to model the spontaneous chemical replication of genetic material within a protocell." ([url http://genetics.mgh.harvard.edu/szostakweb/publications/Szostak_pdfs/Mansy_et_al_Nature_2008.pdf][/url])
In other words, the replication is a special case which requires precisely-constructed, preexisting templates.
Same chicken-and-egg scenario as before.
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Edited by OneEye at 06/11/2008 7:32 AM
What a waste of money and time. Nobody has any idea at all what the heck the first cell looked like.
Reply | Report Abuse | Link to thisWhat these guys are basically doing is running mathematical models trying to strip out everything possible in the hopes they can get a working cell that doesn't face a 5000 foot vertical cliff on mount improbable.
When you make claims like this it means you have built up the cell, it means you have created the DNA, you have created the protein structure, it does not sound like they have done that, it looks like they have taken things that already exist and put them together.
Reply | Report Abuse | Link to thisI notice a lot of the comments are very negative. Apparently there is a lot of suspicion around research into the origin of life.
Reply | Report Abuse | Link to thisThis is NOT an example of "intelligent design" by the researchers. This took place spontaneously (in a test tube, granted) when researchers mixed chemicals thought to have been present in the early earth. The only "tinkering" is that a strand of already-constructed DNA was used.
I'm starting a series on the origin of life, alien life, and how it all relates to faith and religion on my blog. If I may be allowed a quick link over there, it's http://ginkgo100.blogspot.com/
(Please)! Could someone discuss the whole series of problems building up a replicating an evolving system of the first cell. Before triumpitly stating.''Scientists Close to Reconstructing First Living Cell" BY FAITH we are to assume that all the problems of replication will be resolved.
Reply | Report Abuse | Link to thisWhy do we refuse the possibilty of an inteligint design? (As Dana Carvy the church lady use to say, (SATAN) or is it good old human pride LOL)
"Learn from yesterday, live for today, hope for tomorrow. The important thing is not to stop questioning". Albert Einstein
We sure can't use GOD as a anwser we would run out of questons, and we can't have that.
It's sad to see only ten comments on such an important issue.
(Please)! Could someone discuss the whole series of problems building up a replicating an evolving system of the first cell. Before triumpitly stating.''Scientists Close to Reconstructing First Living Cell" BY FAITH we are to assume that all the problems of replication will be resolved.
Reply | Report Abuse | Link to thisWhy do we refuse the possibilty of an inteligint design? (As Dana Carvy the church lady use to say, (SATAN) or is it good old human pride LOL)
"Learn from yesterday, live for today, hope for tomorrow. The important thing is not to stop questioning". Albert Einstein
We sure can't use GOD as a anwser we would run out of questons, and we can't have that.
It's sad to see only ten comments on such an important issue.
(Please)! Could someone discuss the whole series of problems building up a replicating an evolving system of the first cell. Before triumpitly stating.''Scientists Close to Reconstructing First Living Cell" BY FAITH we are to assume that all the problems of replication will be resolved.
Reply | Report Abuse | Link to thisWhy do we refuse the possibilty of an inteligint design? (As Dana Carvy the church lady use to say, (SATAN) or is it good old human pride LOL)
"Learn from yesterday, live for today, hope for tomorrow. The important thing is not to stop questioning". Albert Einstein
We sure can't use GOD as a anwser we would run out of questons, and we can't have that.
It's sad to see only ten comments on such an important issue.
(Please)! Could someone discuss the whole series of problems building up a replicating an evolving system of the first cell. Before triumpitly stating.''Scientists Close to Reconstructing First Living Cell" BY FAITH we are to assume that all the problems of replication will be resolved.
Reply | Report Abuse | Link to thisWhy do we refuse the possibilty of an inteligint design? (As Dana Carvy the church lady use to say, (SATAN) or is it good old human pride LOL)
"Learn from yesterday, live for today, hope for tomorrow. The important thing is not to stop questioning". Albert Einstein
We sure can't use GOD as a anwser we would run out of questons, and we can't have that.
It's sad to see only ten comments on such an important issue.
I can't believe "scientist" still pursue this madness... everyone knows that life doesn't come from non life, apparently not everyone actually. What a waste of taxpayers' and grant-giving money and the worse part is then they put garbage like this in the textbooks, *sigh*.
Reply | Report Abuse | Link to thisBeautiful, i'd like to know whethetr RNA, DNA or any other means of genetic information put itslef together and then started replicating for millions or billions of years if you will. Hypothetically all of a sudden, boom replication, replication and at the end an entire cluster of brainiacs that need millions of hours in a lab to replicate what they (thought) random episodes of creation beacuse at the beginning (creation) has to exist anyway, due to the fact that before nothing there is nothing and when you get something then something did it. (OK)whetehr God or nature and as a matter of fact What nature is?
Reply | Report Abuse | Link to thisThis experiment in no way proves that a cell existed in an different form 3.5 to 4 billion yrs ago. All it shows is that scientists, presuming evolution to be true, using existing genetic materials, BELIEVE, that this might have occurred. All their experiments are always trying to prove evolution to be true while the basis for these experiments is that it already is! Total tautology! Just like they BELIEVE that the earth is billions of years old! Why? Because evolution needs lots of time to operate. When they can PROVE that life arose from non life then I'll listen.
Reply | Report Abuse | Link to thisYes!
Reply | Report Abuse | Link to thisAbsolutely!
Reply | Report Abuse | Link to thisPlus: where did the first phospholipids come from?
How come the name of the team publishing this work in (non-less-than) Nature is not disclosed in this article?
Reply | Report Abuse | Link to this