[...]
>>>Chris: Self-replicating molecules are not exactly uncommon.
>>>DNAunion: I am unaware of any known natural self-replicating molecule
(they are very uncommon in nature, if they exist at all). Note the even DNA
is not
self-replicating (I bring this up because it is sometimes incorrectly stated
that DNA replicates itself).
>>>Chris: Actually, you do know of such molecules: DNA.
***************
DNAunion: DNA is not self-replicating. It requires, among other things, RNA
nucleotides to serve as a primer (DNA polymerases can only extend preexisting
chains, they cannot initiate them) and a slew of proteins (DNA polymerase,
RNA primase, Single-stranded binding proteins, DNA helicases, DNA ligases,
etc.), and therefore, indirectly, the assistance of ribosomes, tRNA, rRNA,
proteins that charge tRNA with amino acids, elongation factors (EF-Tu, for
example), etc.
Finally, DNA has not been shown to form in nature other than from preexisting
DNA.
***************
>>>Chris: You may also be aware of prions.
**************
DNAunion: I am aware of them, but do not keep up with them. It is my
understanding, however, that prions do not self-replicate. If my limited
exposure to the literature on them is anything to go by...
There are two interconvertible forms of a prion protein - a normal and an
abnormal (with the abnormal conformation being the causative agent of
scrapies, bovine spongiform encephalopathy ("Mad Cow disease"), and the other
related diseases). The normal form exists, and when an abnormal form of the
protein makes physical contact with it, it can cause the normal form to
convert to the abnormal form. This would entail only a physical
conformational change of a preexisting macromolecule, not its synthesis: that
is, neither the normal nor the abnormal form makes itself; they both are made
normally (using DNA, mRNA, ribosomes, the genetic code, etc.).
**************
>>>Chris: However, even a water molecule can be self-reproducing in the
right chemical circumstances (i.e., it triggers the production of other water
molecules).
****************
DNAunion: I would still like to see you provide some peer-reviewed
scientific material that states that water molecules are self-reproducing.
I really don't understand what you mean. In simplistic thought experiment
language, If you take two water molecules and put them in a sealed jar,
leave, and come back an hour or a day later, will you have more than 2 water
molecules? If you come back a week later, will the jar be filled with water?
****************
[...]
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