theyeti

I've never heard of an RNA only bacterium either. But not all RNA viruses need DNA. Your standard RNA viruses (not the retroviruses) like influenza use RNA and do not go through a DNA intermediate. Their RNA is simply translated directly (or used as a template to generate a complementary RNA) and is duplicated directly by an RNA polymerase. No DNA involved.

theyeti

caravelair

Severin K, Lee DH, Kennan AJ, and Ghadiri MR, A synthetic peptide ligase. Nature, 389: 706-9, 1997

Lee DH, Granja JR, Martinez JA, Severin K, and Ghadri MR, A self-replicating peptide. Nature, 382: 525-8, 1996

that's just one example, but i think there are others.

Peez

It is worth noting that one can easily assume that one or more supernatural entities (e.g. gods) created cellular life complete with DNA, RNA, proteins, etc., and that this life evolved from there. Most creationists seem to confuse the origin of life (abiogenesis) with evolution.

Peez

God Fearing Atheist

I was under the impression that lipids havent shown up in Miller-esque "primitive soup" experiments.

Do we know how they were formed yet?

-GFA

Mashriqi Mercenary

wow, u guys are full of good information. :notworthy

RBH

This is consistent with Stuart Kauffman's hypothesis that autocatalytic sets of catalytic polymers self-organized very early on, providing the basis for the first replicators and hence evolution. See "The Origins of Order" (1993, pp 298ff).

RBH

faust

Kosmo:

Don't forget prions, which are arguably "self-replecating peptides". no rna or dna needed.

Also it has been shown that there are several types of proteins that can transmit "information" directly along reproductive lines (see + and - strain types in some bacteria). They have proteins that have two or more stable conformations and can catalyze the transformation of other copies of that protein into adopting their conformation, this can be transmitted through replication so long as at least one of the proteins is passed down to the daughter cell (through the cytoplasm). You can mix and match species of bacteria with different "prion" types and transform them from one type to the other. A very similar thing happens in vCJD in humans and prions in other species.

Even the Central Dogma isn't -that- dogmatic

Dr.GH

The amphiphilics are likely in the "tars" that Miller and crew don't analyze. (The often repeated creato claim that Miller (1953) only found a "few" or a "handful" of amino acids is (like many creato misrepresentations technicaly correct) reflects the lack of analysis of the resultant, rather than the lack of diverse products in the resultant).

For other sources of lipids try

D.W. Deamer
"The First Living Systems - A Bioenergetic Perspective", ; Microbiology and Molecular Biology Reviews, 61(2): 239; June 1997

http://shiva.msu.montana.edu/courses...ingsystems.pdf

Dr.GH

Also take a look at

Segre' D., Ben-Eli D. Deamer D. and Lancet D.
2001 “The Lipid World” Origins Life Evol. Biosphere 31, 119-145.

Wounded King

Dear Yeti and Faust,

I wasn't trying to suggest a DNA intermediate was reuired, rather that the cellular hosts DNA was required to provide the functional host cell in the first place. Your point is well made though many if not all of the neccessary components may only require RNA and proteins which would not neccessarily require DNA.

Similary I feel that Fausts statement that there is "no DNA or RNA needed" misses out the obvious requirement for DNA in order to produce the Wild type Prion protein in the first place. This isn't really self-replication, self-propagation perhaps?

TTFN,

Wounded