Post by Ernest MajorPost by MarkEI've raised Steven Benner's "tar paradox" in a recent post; it
subsequently occurred to me that the Miller-Urey experiment is,
ironically, a demonstration of this (I've mentioned this in a another
thread, but thought it deserved a separate post). Miller-Urey produced
* Carboxylic Acids (e.g., formic acid, acetic acid, and succinic
acid): These dominated the product mix, typically making up 80-90% of
the total organic compounds.
Not tar. I found a Miller & Urey paper.
Post by MarkE* Hydroxy Acids (e.g., lactic acid and glycolic acid): Accounted for
5-10% of the total.
Not tar.
Post by MarkE* Amino Acids: Typically contributed about 1-2% of the total organic
product yield.
Not tar. Also the numbers you give below add up to ~4.5%. The number
from a Miller and Urey paper I found give an every larger proportion (by
mole) of amino acids, and carboxylic acids in the 50-60% range.
Post by MarkE* Other Organic Molecules: Small amounts of urea, nitriles, aldehydes,
and hydrocarbons were also formed, constituting the remainder of the
products.
Not tar.
Post by MarkE- Glycine: Approximately 2.1% of the total yield
- Alanine: Around 1.7%
- β-Alanine: About 0.76%
- Aspartic Acid: Approximately 0.024%
- Glutamic Acid: Around 0.051%
I had thought that the Miller-Urey experiment did produce appreciable
quantities of tar. Was I mistaken?
I think so.
"Miller’s experiment did produce the amino acids, but only by
continuously circulating the reaction mixture and isolating products as
they were formed. The quantities were still tiny and not in the same
proportions as found in nature. One of the causes of the low yield has
been identified by Peltzer who worked with Miller. As the amino acids
were formed they reacted with reducing sugars in the Maillard reaction,
forming a *brown tar* around Miller's apparatus. Ultimately, Miller was
producing large compounds called mellanoids, with amino acids as an
intermediate product."
Or this:
"Little discussed by anyone outside the origins of life scientific
community was that the experiment also produced a lot of a dark, sticky
substance, a gooey tar that covered the beaker’s insides. It was
dismissed as largely unimportant and regrettable then, and in the
thousands of parallel origins of life experiments that followed.
Though they do offer this glimmer:
"Today, however, some intrepid researchers are looking at the tarry
residue in a different light."
https://manyworlds.space/2017/09/21/messy-chemistry-a-new-way-to-approach-the-origin-of-life/