TNA Stirs Alphabet Soup, Returns Empty

by Dr. Elizabeth Mitchell on January 21, 2012

ScienceDaily: “Simpler Times: Did an Earlier Genetic Molecule Predate DNA and RNA?TNA-world still doesn’t spell anything.

Evolutionary scientists trying to get around the irreducible complexity of the genetic code keep trying to come up with simpler, more achievable alternatives to explain molecules-to-man evolution. The latest candidate for a pre-biotic “genetic code” is threose nucleic acid (TNA). Proposed and tested by John Chaput’s team at Arizona State University, TNA is thought to be a simpler, more randomly achievable precursor to RNA and DNA. Chaput says the molecule even obeys the rules of Darwinian evolution.

Living organisms use DNA to encode their blueprints onto genes for reproduction and for transcription—copying—onto RNA. RNA then forms templates by which amino acids are assembled into proteins. Even the “simplest” known life forms possess a complex genetic code, so evolutionists search for simpler stepping stones to life. Since RNA, an intermediary between DNA and proteins, carries information and has some enzymatic functions, evolutionists have looked to it as the most essential pre-biotic component. The discovery that certain forms of RNA could assemble themselves without the assistance of additional enzymes popularized the RNA-world hypothesis.1

Since RNA is a pretty complicated molecule, though, the quest for a simpler analog that random chemistry could produce has continued.

Since RNA is a pretty complicated molecule, though, the quest for a simpler analog that random chemistry could produce has continued. Chaput’s report published in Nature asserts TNA is a reasonable “RNA progenitor due to its chemical simplicity and ability to exchange genetic information.”2 TNA is built from a chain of nucleic acids using a four-carbon sugar (threose) instead of the five-carbon ribose used in RNA. Since a four-carbon sugar can be built from two identical two-carbon molecules, Chaput considers it more randomly achievable in the chaos of chemical soup. Chaput’s team reports it has “applied Darwinian evolution methods to evolve . . . a TNA receptor that binds to an arbitrary target”18 and that the TNA sequence folded into a complicated molecular shape required to biologically function as “an ancestral genetic system.”18

Chaput’s team built DNA-TNA hybrids with random sequences to show that, if provided with DNA polymerase enzyme, TNA could form complementary base pairs with DNA. Then they incubated those DNA-TNA strands with a target protein molecule and washed away the strands that didn’t attach to it. Finally, they separated the TNA from the DNA. Since only the TNA that matched the target protein survived the process, they said they had evolved the TNA using Darwinian evolution. And since the TNA strands held their shape, they said TNA transmitted the information stored in the DNA.

The various components of molecular machinery all had to be provided for this “simple” TNA polymer to assemble along DNA templates. One might well question the source of those components in the “pre-RNA world” scenario, but evolutionists are confident that molecules like ribozymes—a form of RNA with enzymatic functions—would answer that need. The TNA polymers took on tertiary structural shapes and held them as a natural result of the chemistry used to construct them. The polymers were built using standard nucleobases. Hydrogen bonds between the atoms of such molecular components stabilize specific shapes. This is the mechanism underlying many biochemical functions. And the “Darwinian evolution” of the TNA involved nothing more than throwing away puzzle pieces that didn’t match the templates. Thus the chemistry used to build the TNA did preserve the information provided by the templates.

The information in the templates, however, is the unconquerable problem for the “pre-RNA world” explanation of molecules-to-life evolution. Even if all those chemicals existed and randomly assembled into the simplest imaginable nucleic acids, what would they mean? What information would they convey? What code would they carry? What would read the code? The nucleobases in the TNA, just like those in RNA and DNA, are an alphabet. But without an understandable language, information to be transmitted, a producer of information, a decoder, and a method of using the decoded information, the nucleobase alphabet would be utterly meaningless.

This entire experiment hinged on providing the TNA with information and seeing if its chemical components could make a sustainable copy of the information. They could. But without God to provide the original information in the genomes of all created kinds of organisms, all the TNA in the world would be just so much chemical chaos.

Biological observations tell us life only comes from life. And information must be provided by a source of information. The living Creator God made all physical matter and all living things in the beginning, about 6,000 years ago. And He created the genetic code to enable all kinds of living things to reproduce and vary within their created kinds. His eyewitness account is in Genesis.

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  1. The RNA-Way From Molecules-to-Man Remains Muddled


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