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Topic: RNA world hypothesis

Related Topics

RNA

RNA gene

Ribozyme

Origin of life

PNA

Messenger RNA

Transfer RNA

Life

Nucleic acid

Primordial soup

Walter Gilbert

Biological cell

Translation (biology)

DNA

Ribosome

	RNA world hypothesis - Wikipedia, the free encyclopedia
		The RNA world hypothesis proposes that RNA was actually the first life-form on earth, later developing a cell membrane around it and becoming the first prokaryotic cell.
		At first glance, the RNA world hypothesis seems implausible because, in today's world, large RNA molecules are inherently fragile and can easily be broken down into their constituent nucleotides with hydrolysis.
		In 2001, the RNA world hypothesis was given a major boost with the deciphering of the 3-dimensional structure of the ribosome, which revealed the key catalytic sites of ribosomes to be composed of RNA, with proteins playing only a structural role in holding the ribosomal RNA together.
	en.wikipedia.org /wiki/RNA_world_hypothesis (1272 words)

	RNA - Wikipedia, the free encyclopedia
		RNA serves as the template for translation of genes into proteins, transferring amino acids to the ribosome to form proteins, and also translating the transcript into proteins.
		Ribosomal RNA (rRNA) is a component of the ribosomes, the protein synthetic factories in the cell.
		RNA genes (sometimes referred to as non-coding RNA or small RNA) are genes that encode RNA that is not translated into a protein.
	en.wikipedia.org /wiki/RNA (1151 words)

	Kids.net.au - Encyclopedia RNA - (Site not responding. Last check: 2007-11-07)
		Structurally, RNA is indistinguishable from DNA except for the critical presence (noted above) of an additional hydroxyl group attached to the pentose ring in the 2' position.
		RNA molecules often fold into more complex structures by making use of complementary internal sequences; that is, one part of a single RNA molecule is the nucleic acid complement of another part of the same molecule (for exampls, 5'-ACUCGA-3' and 5'-UCGAGU-3', or the palindrome 5'-GCAGACG-3' with 5'-CGUCUGC-3'), so that the two strands bind together.
		RNA is less stable than DNA, however, and is also a less efficient catalyst than a protein-based enzyme.
	www.kidsseek.com /encyclopedia-wiki/rn/RNA (960 words)

	"RNA world"
		Advocates of the "RNA world" hypothesis argue that RNA must have come before the first proteins, since without it there would have been no molecule of heredity – no "blueprint" molecule –; and therefore no way for other molecules to have been manufactured consistently.
		According to this idea, there was a time when RNA alone handled all of the tasks required for a cell to survive, acting as both a genetic material and a catalyst for the various reactions involved in metabolism and for its own assembly.
		Opponents of the RNA world picture point to the chemical fragility of RNA and the fact that it is difficult to synthesize abiotically.
	www.daviddarling.info /encyclopedia/R/RNAworld.html (1073 words)

	RNA world hypothesis: Encyclopedia topic (Site not responding. Last check: 2007-11-07)
		RNA and DNA are made of long stretches of specific nucleotide (nucleotide: A phosphoric ester of a nucleoside; the basic structural unit of nucleic acids (DNA or RNA)) s, often referred to as "bases", attached to a sugar-phosphate backbone.
		The RNA world hypothesis holds that in the primordial soup (primordial soup: the primordial sea, or primordial ocean, is a term applied collectively to the oceans...
		In an RNA world, different forms of RNA compete with each other for free nucleotides and are subject to natural selection (natural selection: A natural process resulting in the evolution of organisms best adapted to the environment).
	www.absoluteastronomy.com /reference/rna_world_hypothesis2 (1360 words)

	RNA world - EvoWiki
		This hypothesis was proposed by Francis Crick in 1968, but the hypothesis only gained impetus after Cech's great discovery; the term "RNA world" was composed by Walter Gilbert in 1986.
		Using the honeybee analogy, the RNA world was a solitary-bee phase.
		The hypothesis that the first organisms were constructed from RNA was first suggested by Carl Woese in 1967, and a year later by Leslie Orgel and Francis Crick.
	wiki.cotch.net /index.php/RNA_world (1347 words)

	Gibson, L. J. --- Did Life Begin in an "RNA World"? (Site not responding. Last check: 2007-11-07)
		RNA is present in all living cells, and has a variety of uses that are central to the requirements for life.
		In the case of RNA, the sugar is ribose, the purines are adenine and guanine, and the pyrimidines are cytosine and uracil.
		The importance of RNA to the origin of life is based on the conjecture that it could act both as a source of information and as a catalyst to use that information.
	www.grisda.org /origins/20045.htm (2269 words)

	The RNA World: A Critique - Origins & Design 17:1. Mills, Gordon and Kenyon, Dean
		As researchers broaden their focus to include the chemical plausibility of the RNA World itself, however7, these difficulties cannot be avoided.
		We take heart in noting that, despite the frequent neglect in much of the popular literature of the chemical difficulties of the RNA World scenario, many of the scientists involved with that hypothesis are quite candid in their assessment of the problems associated with it.
		RNA molecules with catalytic activity that are known today predominantly have nuclease or nucleotidyl transferase activity with some minimal esterase actitivy22.
	www.arn.org /docs/odesign/od171/rnaworld171.htm (3431 words)

	Origin of Life - The RNA world
		The "RNA world" hypothesis suggests that the roles of proteins and enzymes were once played by curled-up RNA strands.
		However, the "RNA world" is not itself hypothesis a about the actual origin of life - since RNA is not remotely plausible in the role of the first genetic material.
		RNA world hypothesis, for example, suggests that short RNA molecules could have spontaneously formed that would then catalyze their own continuing replication.
	originoflife.net /rna_world (475 words)

	The Other RNA World -- Riddihough 296 (5571): 1259 -- Science (Site not responding. Last check: 2007-11-07)
		RNA is more than a messenger between genome and protein: Ribosomal RNA has long been recognized as fulfilling a structural role and transfer RNA as fulfilling an adapter role in the conversion of message to protein.
		RNA silencing systems have been described in numerous organisms: posttranscriptional gene silencing (PTGS) and cosuppression in plants, quelling in fungi, and RNAi in animals.
		It is clear that the function of RNAi-based RNA silencing in plants is to defend the genome against foreign, invading nucleic acids--viruses, transposons, and transgenes.
	www.sciencemag.org /cgi/content/summary/296/5571/1259 (802 words)

	Laboratory 'theme park' re-creates RNA world for study
		Because RNA replication is far simpler than protein replication, and because RNA participates in central cellular functions, researchers postulate a primitive, yet elegant, system in which RNA made RNA.
		To demonstrate the feasibility of this hypothesis, researchers must re-create certain aspects of this RNA world in the lab.
		This idea, in contrast to the RNA world's "information first" thesis, posits that a chaotic soup of small, random molecules led to chance metabolic reactions that evolved into modern cellular life.
	www.eurekalert.org /pub_releases/2003-08/wifb-lp082603.php (1295 words)

	Non-Coding RNA Genes and the Modern RNA World.
		Various cis-antisense RNAs have been observed in prokaryotes [50], plants [51] and animals [12], and their roles are unlikely to be limited to those in imprinting and chromatin structure.
		The discovery of RNA catalysis [119, 120] and the "RNA world" hypothesis for the origin of life [26, 121] provide a seductive explanation for why rRNA and tRNA are at the core of the translation machinery: perhaps they are the frozen evolutionary relic of the invention of the ribosome by an RNA-based 'riboorganism' [122].
		Self-splicing RNA: autoexcision and autocyclization of the ribosomal RNA intervening sequence of Tetrahymena.
	www.euchromatin.org /Eddy01.htm (9521 words)

	biology - RNA world hypothesis
		This hypothesis is supported by the RNA's ability to store, transmit, and duplicate genetic information, just like DNA does.
		However, the theory of independent RNA life is much older and can be found in Carl Woese's book The Genetic Code (New York: Harper and Row, 1967).
		Ultraviolet light can cause RNA to polymerize while at the same time breaking down other types of organic molecules that could have the potential of catalyzing the break down of RNA (RNAses), suggesting that RNA may have been a relatively common substance on early earth.
	www.biologydaily.com /biology/RNA_world_hypothesis (1140 words)

	Biology's Theme Park: RNA World :: Astrobiology Magazine ::
		The speculation has been that RNA preceded DNA, or at least formed the early basis for what is considered the biochemical progenitor in such an RNA world of self-reproducing molecules and enzymes.
		In a paper published in the journal Science in 2001, his lab demonstrated one of the first pieces of hard evidence that such a world is at least possible.
		Stuart Kauffman, a biologist and RNA-world skeptic affiliated with the nonprofit research center Santa Fe Institute, believes the RNA hypothesis is narrow and fails to take into account the possibility that other polymeric molecules may be able to self-reproduce without making a copy of a template.
	www.astrobio.net /news/article575.html (1454 words)

	The RNA World. by Brig Klyce
		It was prescient of Crick to guess that RNA could act as an enzyme, because that was not known for sure until it was proven in the 1980s by Nobel Prize-winning researcher Thomas R. Cech (2) and others.
		RNA is then relegated to the intermediate role it has today—no longer the center of the stage, displaced by DNA and the more effective protein enzymes.
		RNA is chemically fragile and difficult to synthesize abiotically.
	www.panspermia.org /rnaworld.htm (5994 words)

	HHMI Bulletin: A World Apart (Site not responding. Last check: 2007-11-07)
		In the hypothetical "RNA World," a vision of the primordial Earth, precursors of modern RNA were responsible for storing genetic information and catalyzing biochemical reactions —functions primarily associated with DNA and enzymes.
		In the often rigid, paradigm-driven world of biology, it was as unexpected as stumbling upon penguins nesting in the Florida Everglades.
		Despite its obvious intellectual appeal, the RNA World was for the most part a quirky conceptual pastime in the years following the discovery of ribozymes.
	www.hhmi.org /bulletin/june2002/rna/rna2.html (2171 words)

	Genetics - Wikipedia, the free encyclopedia
		The study of inherited features not strictly associated with changes in the DNA sequence is called epigenetics.
		Some take the view that life can be defined, in molecular terms, as the set of strategies which RNA polynucleotides have used and continue to use to perpetuate themselves.
		This definition grows out of work on the origin of life, specifically the RNA world hypothesis.
	en.wikipedia.org /wiki/Genetics (1741 words)

	New ligase-derived RNA polymerase ribozymes -- LAWRENCE and BARTEL 11 (8): 1173 -- RNA
		B4 onward, RNA was excised from the interface between the –Hg and +Hg regions, enforcing selection for addition of two 4-thioUs.
		Dworkin, J.P., Lazcano, A., and Miller, S.L. The roads to and from the RNA world.
		Hughes, R.A., Robertson, M.P., Ellington, A.D., and Levy, M. The importance of prebiotic chemistry in the RNA world.
	www.rnajournal.org /cgi/content/full/11/8/1173 (4531 words)

	Origin of Life - Latest Theories/Problems
		The spontaneous formation of a self-replicating RNA (which acts as a catalyst for replication of itself) ensures perpetuation of the RNA, according to the theory.
		However, there is, at present, no explanation for duplication of the original RNA polymer from the complementary strand, in the absence of enzymes.
		Leslie Orgel recently stated, "The full details of how the RNA world, and life, emerged may not be revealed in the near future." Believers in Christ know that the Creator of life has already been revealed through the Bible.
	www.godandscience.org /evolution/rnamodel.html (1455 words)

	RNA world -- Ben's Message Board (Site not responding. Last check: 2007-11-07)
		Nonetheless I've also read that RNA probably suffers from some of the same sort of problems.
		For instance, while some RNA strings have catalytic properties (one of the reasons why DNA requires enzymes) the vast majority don't.
		Nonetheless, I concede that the RNA-world hypothesis has some merit even if it doesn't resolve the problem I was originally concerned with.
	www.voy.com /22190/5172.html (360 words)

	ScienceDaily: Laboratory 'Theme Park' Re-creates RNA World For Study
		If, as the RNA-world hypothesis states, RNA once was in the business of replicating RNA, then enzymes once were composed entirely of RNA and not amino acids -- the building blocks of protein.
		The good news was that these RNA enzymes are flexible and robust enough to bind to just about any kind of template regardless of its sequence -- findings that eluded earlier experiments.
		Whitehead Study Supports Existence Of Ancient RNA World, Helps Provide Insight Into Early Evolution Of Life (September 17, 1998) -- For decades, many researchers thought that ribonucleic acid, or RNA, was nothing more than a molecular interpreter that helps translate DNA codes into proteins.
	www.sciencedaily.com /releases/2003/08/030827071101.htm (2559 words)

	Cairns-Smith: detailed criticisms of the RNA world hypothesis
		Graham Cairns-Smith is well known for a bizarre theory that the first living organisms were clay minerals of the origin of life.
		But not so well known is that he is driven to such outlandish ideas by the enormous chemical difficulties of mainstream theories of chemical evolution, such as the RNA World (see also The RNA World: A Critique):
		If it is hard to imagine polypeptides or polysaccharides in primordial waters it is harder still to imagine polynucleotides.
	www.answersingenesis.org /Home/area/Tools/Quotes/cairns-smith_RNA.asp (1325 words)

	More thoughts. -- Ben's Message Board
		The problem is that without evolution it seems unlikely to get a self-replicating ribozyme, but without self-replication you can't conduct an evolutionary search for the first, primitive self-replicating ribozyme.
		Basically, a big problem with the RNA world scenario is this: how to get the RNA strings to begin with?
		Furthermore, a real problem for the RNA world hypothesis is getting the self-replicating RNA in the first place (e.g.
	www.voy.com /22190/5195.html (557 words)

	Whitehead Institute - "Theme Park" Re-creates RNA World for Study
		Scientist David Bartel is hard at work on what might seem an impossibility—a microscopic theme park whose motif, the origins of life, is of equal interest to both scientists and philosophers.
		If, as the RNA-world hypothesis states, RNA once was in the business of replicating RNA, then enzymes once were composed entirely of RNA and not amino acids—the building blocks of protein.
		Wholly independent in its governance, finances and research programs, Whitehead shares a close affiliation with the Massachusetts Institute of Technology through its faculty, who hold joint MIT appointments.
	www.wi.mit.edu /news/archives/2003/db_0826.html (1439 words)

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