blog.wired.com/wiredscience/2008/09/biologists-on-t.html
Jack Szostak, a molecular biologist at Harvard Medical School, is building simple cell models that can almost be called life. Szostak's protocells are built from fatty molecules that can trap bits of nucleic acids that contain the source code for replication. Combined with a process that harnesses external energy from the sun or chemical reactions, they could form a self-replicating, evolving system that satisfies the conditions of life, but isn't anything like life on earth now, but might represent life as it began or could exist elsewhere in the universe.
XV International Conference on the Origin of Life in Florence, Italy, last week. The replication isn't wholly autonomous, so it's not quite artificial life yet, but it is as close as anyone has ever come to turning chemicals into biological organisms. "We've made more progress on how the membrane of a protocell could grow and divide," Szostak said in a phone interview.
sequences, but we need to be able to copy arbitrary sequences so that sequences could evolve that do something useful." By doing "something useful" for the cell, these genes would launch the new form of life down the Darwinian evolutionary path similar to the one that our oldest living ancestors must have traveled. Though where selective pressure will lead the new form of life is impossible to know.
Sheref Mansy, a former member of Szostak's lab and now a chemist at Denver University. Protocellular work is even more radical than the other field trying to create artifical life: synthetic biology. Even J Craig Venter's work to build an artificial bacterium with the smallest number of genes necessary to live takes current life forms as a template. Protocell researchers are trying to design a completely novel form of life that humans have never seen and that may never have existed. Over the summer, Szostak's team published major papers in the journals Nature and the Proceedings of the National Academy of Sciences that go a long way towards showing that this isn't just an idea and that his lab will be the first to create artificial life -- and that it will happen soon.
Jeffrey Bada, a University of California San Diego chemist who helped organize the Origin of Life conference. Modern life is far more complex than the simple systems that Szostak and others are working on, so the protocells don't look anything like the cells that we have in our bodies or Venter's genetically-modified E coli.
Hans Ziock, a protocellular researcher at Los Alamos National Laboratory. Life's function, as a simple nanomachine, is just to use energy to marshal chemicals into making more copies of itself. "You need to organize yourself in a specific way to be useful," Ziock said. "You take energy from one place and move it to a place where it usually doesn't want to go, so you can actually organize things." Modern cells accomplish this feat with an immense amount of molecular machinery. In fact, some of the chemical syntheses that simple plants and algae can accomplish far outstrip human technologies. Even the most primitive forms of life possess protein machines that allow them to import nutrients across their complex cell membranes and build the molecules that then carry out the cell's bidding. Those specialized components would have taken many, many generations to evolve, said Ziock, so the first life would have been much simpler.
What most researchers agree on is that the very first functioning life would have had three basic components: a container, a way to harvest energy and an information carrier like RNA or another nucleic acid. Szostak's earlier work has shown that the container probably took the form of a layer of fatty acids that could self-assemble based on their reaction to water (see video). One tip of the acid is hydrophilic, meaning it's attracted to water, while the other tip is hydrophobic. When researchers put a lot of these molecules together, they circle the wagons against the water and create a closed loop. These membranes, with the right mix of chemicals, can allow nucleic acids in under some conditions and keep them trapped inside in others.
That opens the possibility that one day, in the distant past, an RNA-like molecule wandered into a fatty acid and started replicating. That random event, through billions of evolutionary iterations, researchers believe, created life as we know it.
The entire line of research, though, begs the question: where would DNA, or any other material carrying instructions for replication, have come from? Many researchers have tried to tackle this problem of how RNA- or DNA-like molecules could have developed from the amino acids present on the early Earth.
But while many scientists agree the protocell work is impressive, not every scientist is convinced that it contributes to a reasonable explanation for the origin of life.
Mike Russell, a geochemist with the Jet Propulsion Laboratory in Pasadena, California. "It's just that I'm uneasy about the significance of it to the origin of life." Russell argues that the very first life-like molecules on Earth would have been based on inorganic compounds. Instead of a fatty acid membrane, Russell argues that iron sulfide could have provided the necessary container for early cells. But UCSD's Bada pointed out that it as unlikely we will ever know how life actually began.
point, and how we all view it, is that it's a nice model, but it doesn't necessarily mean that it happened that way," he said. Szostak suggested that even if life could theoretically or did begin some other way, his lab's hypothesis was (at least) experimentally plausible. "We're now pretty much convinced that growth and division could occur under perfectly reasonable prebiotic conditions in a way that is not some artificial laboratory construction," he said. And actually, the most intriguing possibility of all may be that the protocells in Szostak's lab do not closely model earthly life's origins. If that's true, human beings, ourselves the product of evolution from the most primitive organisms, would have created an alternative path to imbuing matter with the properties of life. "What we have in biology is just one of many, many possibilities," Szostack said. "One of the things that always comes up when people talk about life and universal qualities is water. What if we could design a system that works in something else?"
Sep 8, 2008 9:52:47 AM I don't think this really lends more or less to creationism, since there is an intelligent agent (us) involved in the creation of the lifeform. We being creators ourselves really kind of gives new meaning to humans being made "in the image of God," though.
Sep 8, 2008 10:27:39 AM There are only two places this can lead. The first is into a hyper-intelligent, incredibly tough and nimble organism that likes to snack on humans and the second is into something that turns most of us into zombies. PLEASE stay away from the future and redirect your efforts to creating new iPhone accessories.
Sep 8, 2008 10:29:05 AM Michael - if we are made in the image of God, and he is invisible, why aren't we? As humans we explore, we ask questions, we test theories and we wonder.
Sep 8, 2008 10:44:39 AM @Michael No, the idea here is that they use conditions that could have been present when the planet was new, and if they can get it to work, then this is how it may have happened back then. The reason that it could be a blow to the creationist ideas is because it would mean that a creator is unnecessary, it would prove abiogenesis could have occurred. But for the same reason that it won't destroy creationism, it shouldn't: no matter what they do in a lab, we'll never know for sure exactly what happened unless we can master time travel. Having a pretty good idea is the best we'll be able to ask for. Just knowing that it is indeed possible for spontaneous organic life to occur out of inorganic material is plenty, really. And if your faith is strong enough, then you will believe anyway, no matter what the evidence indicates (as proven time and time again with this group). Which is all the more reason why I never understood what their issue with science is. And why do the...
|
http://csua.com/feed/