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RNA is able to both store genetic information and perform enzymatic functions. This combination of functions allows RNA to potentially act as a template as well as a catalyst for its own replication, and is one of the primary reasons that RNA is thought to be the original polymer of life. It is hypothesized that RNA used these functions to generate a simple life cycle that then increased in complexity due variation and subsequent natural selection. Eventually, evolution could produce modern life. RNA is expected to have preceded DNA as the original information carrier because it requires less energy to form, and thymine (one of DNA’s possible bases) is formed from a chemical process that utilizes uracil (one of RNA’s possible bases.) DNA cannot catalyze reactions, so it could not have originated and replicated on its own before RNA. Ribonucleotides (not deoxyribonucleotides) are also utilized in the “most universal system of catabolism and energy supply of extant organisms.” (1) RNA is expected to have preceded proteins because X-ray calligraphy has shown (6) that RNA catalyzes the synthesis of proteins across all life forms within the ribosome. The proteins of the ribosome appear to function as structural support (Figure 1). DNA and proteins are hypothesized to have been additions to the RNA life system in accordance with reductive evolution of the RNA itself. | RNA is able to both store genetic information and perform enzymatic functions. This combination of functions allows RNA to potentially act as a template as well as a catalyst for its own replication, and is one of the primary reasons that RNA is thought to be the original polymer of life. It is hypothesized that RNA used these functions to generate a simple life cycle that then increased in complexity due variation and subsequent natural selection. Eventually, evolution could produce modern life. RNA is expected to have preceded DNA as the original information carrier because it requires less energy to form, and thymine (one of DNA’s possible bases) is formed from a chemical process that utilizes uracil (one of RNA’s possible bases.) DNA cannot catalyze reactions, so it could not have originated and replicated on its own before RNA. Ribonucleotides (not deoxyribonucleotides) are also utilized in the “most universal system of catabolism and energy supply of extant organisms.” (1) RNA is expected to have preceded proteins because X-ray calligraphy has shown (6) that RNA catalyzes the synthesis of proteins across all life forms within the ribosome. The proteins of the ribosome appear to function as structural support (Figure 1). DNA and proteins are hypothesized to have been additions to the RNA life system in accordance with reductive evolution of the RNA itself. | ||
==Major Discoveries Supporting the Hypothesis== | |||
===Abiotic Formation and Polymerization=== | |||
The discovery of a reaction that can create ribonucleotides without enzymes was a crucial discovery within the development of the RNA world hypothesis because it provided a possible way that RNA could have formed in an abiotic manner. In addition, “the discovery of non-enzymatic intramolecular (cys) and intermolecular (trans) rearrangements of RNA nucleotide sequences in aqueous solutions in the presence of magnesium ions via spontaneous transesterification reactions” has also provided tremendous support to the RNA World Hypothesis. This phenomenon gives a possible mechanism for the formation of RNA polymers from the oligoribonucleotides that could form on early earth. It also provides a way for there have been variances within these polymers, which would be necessary for natural selection to occur. There are multiple ways that transesterification reactions can occur (Figure 2). | |||
===Colony Formation=== | |||
A second crucial discovery was that RNA could form molecular colonies on moist solid surfaces. In order for RNA to undergo natural selection, a form of compartmentalizing is necessary to create “individuals” that can be selected between, and will not break down once selected for. | |||
[[Image:Ebola virus 1.jpeg|thumb|300px|right|Electron micrograph of the Ebola Zaire virus. This was the first photo ever taken of the virus, on 10/13/1976. By Dr. F.A. Murphy, now at U.C. Davis, then at the CDC.]] | [[Image:Ebola virus 1.jpeg|thumb|300px|right|Electron micrograph of the Ebola Zaire virus. This was the first photo ever taken of the virus, on 10/13/1976. By Dr. F.A. Murphy, now at U.C. Davis, then at the CDC.]] | ||
Revision as of 21:16, 9 April 2014
The RNA World Hypothesis is one of the widely accepted theories about the origin of life on earth. The complexity of modern life is one of the most astonishing aspects of our world. The way in which DNA, RNA, and proteins work together to create this complexity is still far from our understanding. One of most perplexing aspects of modern life revolves around the question: “How did it originate?” The RNA World Hypothesis proposes that RNA’s intrinsic properties allowed it generate life on its own. Since the formulation of the RNA World Hypothesis, research and experiments have been conducted in an attempt to support it. However, there are many seemingly paradoxical and highly improbable circumstances that would need to have occurred for the hypothesis to be valid.
Why RNA?
RNA is able to both store genetic information and perform enzymatic functions. This combination of functions allows RNA to potentially act as a template as well as a catalyst for its own replication, and is one of the primary reasons that RNA is thought to be the original polymer of life. It is hypothesized that RNA used these functions to generate a simple life cycle that then increased in complexity due variation and subsequent natural selection. Eventually, evolution could produce modern life. RNA is expected to have preceded DNA as the original information carrier because it requires less energy to form, and thymine (one of DNA’s possible bases) is formed from a chemical process that utilizes uracil (one of RNA’s possible bases.) DNA cannot catalyze reactions, so it could not have originated and replicated on its own before RNA. Ribonucleotides (not deoxyribonucleotides) are also utilized in the “most universal system of catabolism and energy supply of extant organisms.” (1) RNA is expected to have preceded proteins because X-ray calligraphy has shown (6) that RNA catalyzes the synthesis of proteins across all life forms within the ribosome. The proteins of the ribosome appear to function as structural support (Figure 1). DNA and proteins are hypothesized to have been additions to the RNA life system in accordance with reductive evolution of the RNA itself.
Major Discoveries Supporting the Hypothesis
Abiotic Formation and Polymerization
The discovery of a reaction that can create ribonucleotides without enzymes was a crucial discovery within the development of the RNA world hypothesis because it provided a possible way that RNA could have formed in an abiotic manner. In addition, “the discovery of non-enzymatic intramolecular (cys) and intermolecular (trans) rearrangements of RNA nucleotide sequences in aqueous solutions in the presence of magnesium ions via spontaneous transesterification reactions” has also provided tremendous support to the RNA World Hypothesis. This phenomenon gives a possible mechanism for the formation of RNA polymers from the oligoribonucleotides that could form on early earth. It also provides a way for there have been variances within these polymers, which would be necessary for natural selection to occur. There are multiple ways that transesterification reactions can occur (Figure 2).
Colony Formation
A second crucial discovery was that RNA could form molecular colonies on moist solid surfaces. In order for RNA to undergo natural selection, a form of compartmentalizing is necessary to create “individuals” that can be selected between, and will not break down once selected for.
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Legend/credit: Electron micrograph of the Ebola Zaire virus. This was the first photo ever taken of the virus, on 10/13/1976. By Dr. F.A. Murphy, now at U.C. Davis, then at the CDC.
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