Aptameters

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Excerpt Some scientists believe that RNA, a fundamental building block of life, holds the key to life's origin. It was once believed that RNA (ribonucleic acid) was subordinate to DNA, which contains information for making proteins... Continue reading

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This article was first published in the March 2006 ABR Electronic Newsletter.


Some scientists believe that RNA, a fundamental building block of life, holds the key to life's origin. It was once believed that RNA (ribonucleic acid) was subordinate to DNA, which contains information for making proteins. The information carried by DNA is copied onto RNA molecules, which carry the information to ribosomes, biochemical "factories" that make proteins. These proteins then create living tissues. Nobel Prize-winning biologist Tom Czech discovered that some RNA molecules, called ribozymes, carry information like DNA does and carry out biochemistry like proteins do (Zimmer 2004: 36).

All life is based on DNA, but scientists have long wondered what came before it, since it can't survive without proteins. RNA might hold the answer. Observing ribozymes showed how primordial RNA could, like DNA, store genetic information, and could also act like an enzyme (a protein that modifies other proteins). Simple RNA-based life forms could have existed before DNA, spreading across the early Earth, eventually developing the ability to assemble proteins and build DNA molecules. Because these new proteins and DNA did RNA's job better, they took over (ibid. 37).

To test this theory, Harvard biochemist Jack Szostak and two colleagues tinkered with RNA molecules to try and get them to act as a replicase, an enzyme that replicates other RNA molecules. They created a molecule that was able to grab shorter chunks of RNA and duplicate them. "It was a remarkable achievement," reported the science journal Discover, but Szostak knew it was only a small step toward something that could accurately be called alive. Enzymes in living cells can make duplicate RNA sequences one nucleotide at a time [nucleotides are molecules that comprise the links in DNA and RNA chains]. Szostak's ribozyme could only piece together chains of RNA, each of which was several nucleotides long. And his new molecule was grievously sloppy, making regular copying errors. In a single generation, it could turn a life-sustaining genetic code into sheer gibberish. To create a better molecule, Szostak decided to turn to the father of evolutionary theory, Charles Darwin, for inspiration: "We realized that if we were really going to have a chance to have an RNA replicase, we were going to have to evolve it" (ibid. 37).

Actually, blind, random evolution was not involved. What Szostak and his team came up with was a product of intelligent, directed design. They started an "evolutionary cycle" by stringing together nucleotides to create trillions of RNA molecules, and then waited to see if any of them latched onto another molecule. Very few of them did, and only very slowly. Szostak then extracted these successful molecules and made trillions of new copies of them, allowing some random mutations to occur in the process. He then allowed this new generation to grab onto other molecules, and selected the ones that did so the fastest. Szostak's team repeated this process dozens of times, resulting in RNA molecules that were, in Discover's words, "exquisitely well adapted to the job at hand." Szostak named them aptameters, meaning "parts that fit." These aptameters were capable of performing numerous tasks, including binding to a specific virus, grabbing certain kinds of cells, or attaching themselves to vitamins (ibid. 37-8).

Szostak's experiment did not prove Darwinism. His aptameters did not come into existence on their own; they were created. They did not evolve their abilities by chance, but by Szostak's direct involvement. Despite the fact that Szostak's aptameters were designed, Discover admitted that these creatures pale in comparison to real life forms, which evolutionists insist came about WITHOUT a designer:

The best proof that life got its start as an RNA-based organism would be to create one. But for all the advances to date, there's still plenty of work left to do before such a creature comes to life. A handful of ribozymes in a beaker - no matter how accomplished they may be - simply doesn't make the cut (ibid. 38)...[Whatever might be created] will basically have no biochemistry. It won't be able to live outside the lab (ibid. 41).

Szostak, not chance, was the designer; Discover even referred to him as a "would-be creator" in the caption under his photograph (ibid. 37). If Szostak's aptameters could only come about by specific creation, then it is practically impossible that the infinitely more complex ribozymes of primordial earth came about by sheer chance.

Recommended Resources for Further Study

     
The Myth of
Natural Origins
The Big Argument The Genesis Record


Reference
Zimmer, C. 2004. "What Came before DNA?" Discover 25, no. 6.

Stephen Caesar holds his master's degree in anthropology/archaeology from Harvard. He is a staff member at Associates for Biblical Research.

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