Which Came First?

[pastorkevin73]

I have a question for the TEs. Which evolved first RNA or DNA?

 

[Mallon]

Most experts believe RNA predates DNA. Check out the RNA world hypothesis.

 

[philadiddle]

I have a question for the TEs. Which evolved first RNA or DNA?

Most likely it was RNA

 

[EnemyPartyII]

RNA.

Is this a trick question?

 

[metherion]

Also, RNA would not have evolved, it would have formed first. Since RNA in and of itself is not alive... you get the idea.

Metherion

 

[EnemyPartyII]

Also, RNA would not have evolved, it would have formed first. Since RNA in and of itself is not alive... you get the idea.

Metherion

Point of order...RNA may have evolved without being alive. Evolution does not require life to occur, merely self replicating systems.

 

[metherion]

Point of order...RNA may have evolved without being alive. Evolution does not require life to occur, merely self replicating systems

This is correct, and I may very well be mistaken.

I simply do not know enough about advanced organic chem to know if RNA can self-replicate outside a cell, or not, to determine further. But you have a very good point

However, if I remember correctly, in space and other areas without self-replicating systems, some of the bases from RNA and DNA have been found, which is why I said what I said

But space, earth, HUGE difference lol.

Metherion

 

[EnemyPartyII]

This is correct, and I may very well be mistaken.

I simply do not know enough about advanced organic chem to know if RNA can self-replicate outside a cell, or not, to determine further. But you have a very good point

However, if I remember correctly, in space and other areas without self-replicating systems, some of the bases from RNA and DNA have been found, which is why I said what I said

But space, earth, HUGE difference lol.

Metherion

In the right conditions, RNA certainly can self replicate outside of a cell. However, in abiogenesis theory, it is important to remember that no one is suggesting RNA spontaneously appeared and started doing its thing. There is almost certainly a very, very long line of precursor self replicators before RNA, each of THEM evolved from a simpler one. More efficient self replicators evolved, which then outcompeted their precursors, until we have RNA< which gave way to DNA. Were it not for Virusses and DNA's cooption of RNA to do its work for it, I would hypothosise that RNA would likely have gone the way of other precursors by now and been outcompeted by its decendent, DNA.

There are several examples of non RNA or DNA self replicators, even some non organic ones. The ones it is easiest to find info on are prions, as they seem to have had the most research done. Its an interesting field.

 

[Sphinx777]

Ribonucleic acid (RNA) is a biologically important type of molecule that consists of a long chain of nucleotide units. Each nucleotide consists of a nitrogenous base, a ribose sugar, and a phosphate. RNA is very similar to DNA, but differs in a few important structural details: in the cell, RNA is usually single-stranded, while DNA is usually double-stranded; RNA nucleotides contain ribose while DNA contains deoxyribose (a type of ribose that lacks one oxygen atom); and RNA has the base uracil rather than thymine that is present in DNA.

RNA is transcribed from DNA by enzymes called RNA polymerases and is generally further processed by other enzymes. RNA is central to the synthesis of proteins. Here, a type of RNA called messenger RNA carries information from DNA to structures called ribosomes. These ribosomes are made from proteins and ribosomal RNAs, which come together to form a molecular machine that can read messenger RNAs and translate the information they carry into proteins. There are many RNAs with other roles – in particular regulating which genes are expressed, but also as the genomes of most viruses.

 

[OrdinaryClay]

I have a question for the TEs. Which evolved first RNA or DNA?

The most popular speculation among origin of life researchers is that RNA preceded DNA. It is deeply speculative and based mainly on the fact that RNA can act as both an information template and as a catalyst. DNA and Protein (the other two pillars of life) only fill the role of one or the other. There are major critics of the RNA world ideas, see the writings of Robert Shapiro.

The problem with abiogenesis is that you need both necessity and chance, that is you need both deterministic chemical reactions and probabilistic resources to come up with a solution. We are "light years" from a workable theory.

 

[EnemyPartyII]

nonsense. we are but one click away from workable theories
Abiogenesis - Wikipedia, the free encyclopedia

 

[OrdinaryClay]

Point of order...RNA may have evolved without being alive. Evolution does not require life to occur, merely self replicating systems.

You are playing with words a bit. Evolution as in change through time does not specifically require life, but the ability to gain selective advantage and maintain that advantage does require life. A self replicating molecule still faces the big bad world of chemical thermodynamics. The essence of living evolution is the ability to "capture" the advantage of random change and then maintain that change despite deterministic pressure to lose it. Life does this via homeostasis, metabolism and replication.

 

[OrdinaryClay]

nonsense. we are but one click away from workable theories
Abiogenesis - Wikipedia, the free encyclopedia

No offense, but I'm not sure if you meant that as a joke. There is nothing in the wiki link you provided that demonstrates we are close to a theory.

 

[EnemyPartyII]

No offense, but I'm not sure if you meant that as a joke. There is nothing in the wiki link you provided that demonstrates we are close to a theory.

<LI class=toclevel-1>3 Current models

• 3.1 Origin of organic molecules
  • 3.1.1 "Soup" theory today: Miller's experiment and subsequent work
    • 3.1.1.1 Regarding the reducing atmosphere
    • 3.1.1.2 Regarding monomer formation
    • 3.1.1.3 Regarding monomer accumulation
    • 3.1.1.4 Regarding further transformation
  • 3.1.2 The deep sea vent theory
  • 3.1.3 Fox's experiments
  • 3.1.4 Eigen's hypothesis
  • 3.1.5 Wächtershäuser's hypothesis
  • 3.1.6 Radioactive beach hypothesis
  • 3.1.7 Models to explain homochirality
  • 3.1.8 Self-organization and replication
• 3.2 From organic molecules to protocells
  • 3.2.1 "Genes first" models: the RNA world
  • 3.2.2 "Metabolism first" models
    • 3.2.2.1 Iron-sulfur world
    • 3.2.2.2 Thermosynthesis world
    • 3.2.2.3 Possible role of bubbles

<LI class=toclevel-1>4 Other models

• 4.1 Autocatalysis
• 4.2 Clay theory
• 4.3 Gold's "Deep-hot biosphere" model
• 4.4 "Primitive" extraterrestrial life
• 4.5 Lipid World
• 4.6 Polyphosphates
• 4.7 PAH world hypothesis
• 4.8 Multiple genesis

There's a bunch of theories right there.

Or when you say "we aren't close to a workable theory of" do you actually mean "we havn't definitively identified the actual method of"... because they are quite seperate statements.

 

[OrdinaryClay]

[/LIST]There's a bunch of theories right there.

Or when you say "we aren't close to a workable theory of" do you actually mean "we havn't definitively identified the actual method of"... because they are quite seperate statements.

You made the claim we had "workable theories". These are all gross speculations some of which are borderline science fiction. I suspect the wiki authors were attempting to lend credibility to the myth that we have an inkling of understanding of how abiogenesis occurred. We don't.

I meant a theory in the normal scientific sense.

 

[EnemyPartyII]

You made the claim we had "workable theories". These are all gross speculations some of which are borderline science fiction. I suspect the wiki authors were attempting to lend credibility to the myth that we have an inkling of understanding of how abiogenesis occurred. We don't.

I meant a theory in the normal scientific sense.

Whats that, an apparently logical hypothesis explaining a phenomena that is contiguous with all available experimental and/or observational evidence?

 

[OrdinaryClay]

Whats that, an apparently logical hypothesis explaining a phenomena that is contiguous with all available experimental and/or observational evidence?

Yes, it needs to be able to explain to start with.

There is plenty written on the Internet as to what a scientific theory is.

 

[EnemyPartyII]

Yes, it needs to be able to explain to start with.

There is plenty written on the Internet as to what a scientific theory is.

How do the above theories not explain something?

 

[OrdinaryClay]

How do the above theories not explain something?

In fairness, the burden of explanation falls on the person claiming explanatory power, but in a nutshell they don't explain abiogenesis. At worst they are wildly speculative, and at best they describe some basic processes but leave huge unbridgeable gaps in their extrapolation to life.

 

[MattLangley]

In fairness, the burden of explanation falls on the person claiming explanatory power, but in a nutshell they don't explain abiogenesis. At worst they are wildly speculative, and at best they describe some basic processes but leave huge unbridgeable gaps in their extrapolation to life.

Lacking as they are they are workable in comparison to:

"God did it"

(which is not an explanation but a lack of one, which is never a valid explanation)