Another fatal blow to chemical evolution theories is the problem of isomers/isomerization. Specific molecules required on chemical pathways to life have multiple isomers with the same chemical formula but with different structure. This is different from the problem of selection of L-amino acids (left hand polarization).
From page 52 of the above link:
"For example, results from Miller's spark discharge experiments (table 4-1) show many more non-proteinous than proteinous amino acids. In most cases more than one isomer (molecules with the same number of atoms but different geometry) is found for a given empirical formula. For example, three amino acid isomers are formed with formula C.H9N03, two of which are non-proteinous. All eight isomers of formula C4H9N02 are non-proteinous (fig. 4-3)."
And from page 54:
"Figure4-3.
cr-Amino-n-butyric acid
cr-Aminoisobutyric acid
N-Ethylglycine
P-Amino-n-butyric acid
P-Aminoisobutyric acid
-y-Aminobutyric acid
N-Methylalanine
N-Methyl-p-alanine
Structural isomers of amino acids with empirical formula C.H9NOz found in Miller experiment. None are found in proteins."
Format put a period for 4 and z for 2 - the formula is C4H9NO2
See figure 4-3 for the different structures/isomers for the non-biologic amino acids C4H9NO2.
OK, time for my breakfast! I am a little late on that my tummy is telling me!
Hope you all have a good day!
Shelter in place to be safe for you and others. (unless you have a hazmet (sp?) suit).
Claim CB025:
Stanley Miller's original abiogenesis experiment produced only four of the twenty amino acids from which proteins are built, and later experiments still have not produced all twenty amino acids under plausible conditions.
Source:
Watchtower Bible and Tract Society. 1985.
Life--How Did It Get Here? Brooklyn, NY, pg. 40.
Response:
- Miller's experiments produced thirteen of the twenty amino acids used in life (Henahan 1996). Others may have formed via other mechanisms. For example, they may have formed in space and been carried to earth on meteors (Pizzarello and Weber 2004).
- It is not known which amino acids are needed for the most primitive life. It could be that the amino acids that form easily were sufficient and that life later evolved to produce and rely on others.
References:
- Henahan, Sean. 1996. From primordial soup to the prebiotic beach: An interview with exobiology pioneer, Dr. Stanley L. Miller. http://www.accessexcellence.org/WN/NM/miller.html
- Pizzarello, S. and A. L. Weber. 2004. Prebiotic amino acids as asymmetric catalysts. Science 303: 1151.
Hollie - thank you for addressing the actual amino acids produced by Miller but you missed Miller's original experiments vs. his later experiments and also have ignored my reference to this link:
This is a science book - our literature does not go into the detail that Thaxton et al do. I already posted the detailed results of Miller's experiments - I see I need to repost since you seem to want to ignore the chemical reaction product proportions of Miller's experiments (plural). For example, I already posted the detailed list of Miller's experiment in 1974 from table 3-2 from page 23 of the above link.
Of course, I am not going to simply repost - I will address your point specifically and in more detail:
From page 22:
"Electrical Discharge Experiments
At the University of Chicago in December 1952, Stanley Miller provided the first experimental test of the Oparin-Haldane hypothesis of a biogenesis. 4 As a graduate student working in the laboratory of Nobel Laureate Harold Urey, Miller devised an experimental approach to simulate the formation of biomonomers on the early earth. The simulated atmosphere consisted of methane, ammonia, hydrogen, and water vapor."
Note the environment: methane (CH4), ammonia (NH3), Hydrogen (H) and water vapor (H2O). Note that only water contains oxygen and that hydrogen is extremely dominant in this environment. The actual evidence from earth's geology is contrary to this imagined environment - for example, oxygen is the most abundant element in earth's crust - as I also have already posted.
Reference 4 - Stanley L. Miller, 1953. Science 117, 528
Thaxton et al (Bradley & Olson) go on to detail the apparatus Miller used (figure 3-1 on page 21) and the way he determined the chemical reaction products - see the link for that. On page 23 the subsequent experiments (since 1952) by Miller and others is referred to:
"These have included mixtures of two or more of the following gases: methane, ethane, ammonia, nitrogen, water vapor, hydrogen, carbon monoxide, carbon dioxide, and hydrogen sulfide. By and large these experiments follow the same general technique used by Miller, although a number of modifications have been employed. As long as oxygen has been excluded from the mixture, amino acids and other organic compounds have resulted."
As I have already posted, the chemical reaction product proportions vary in different environments - e.g. hot, cold, wet, dry (even with condensing agents), acid, alkaline (etc.) - these variant environments produce mostly formic acid, and then various other compounds including certain amino acids in variant proportions and context depending on the environment in the synthesis experiment.
The specific results reported by Miller in table 3-2 (from page 23 Ibid.) [from the caption} are:
"From S. Miller, 1974. Origins of Life 5, 139." I already posted table 3-2 but I did not detail the chemical reaction product proportions reported by Miller. I will start that in my next post (it will take many posts because there were many amino acids produced (the table includes only the amino acids produced - not other compounds [e.g. organic compounds] like formic acid which predominated).
Thaxton et al goes on (from pages 23,24):
"In 1974, Miller reported the amino acids he had obtained in electrical discharge experiments.8 These are listed in table 3-2. In addition, asparagine,9 lysine,10 and phenylalanine11 have been reported by others but disputed by Miller.t2 In all, ten of the twenty proteinous amino acids have been positively identified among the products of electrical discharge experiments, as well as about thirty non-proteinous amino acids. Both tert-leucine and N-ethylalanine have been reported but not definitely confirmed. When more than trace amounts of ammonia have been used, iminodiacetic acid and iminoaceticpropionic acid have resulted. When hydrogen sulfide is added to the gaseous mixture methionine is formed."
Reference 8 (from which table 3-2 is derived):
Miller and Orgel, The Origins of Life on the Earth, p. 84. See also: D. Ring, Y. Wolman, N. Friedmann, and S. Miller, 1972. Proc. Nat. Acad. Sci. USA 69, 765; Y. Wolman, W.J. Haverland, and S.L. Miller, 1972. Proc. Nat. Acad. Sci. USA 69, 809; S. Miller, 1955. J. Am. Chem. Soc. 77,2351.
Feel free to check these sources Hollie - a number are peer reviewed which you prefer.
Notice that 10 of the 20 amino acids in life (=biologic; specifically proteinous) are positively identified resulting from Miller type synthesis experiments - why your quote refers to only 4 rather than 10 I will research concurrent with researching table 3-2. But I suspect only 4 biologic/proteinous amino acids were produced in significant chemical reaction product proportions.
I will post in detail in concerning Miller's synthesis experiment results in my next posts - but for starters the most prevalent amino acids produced were Glycine (440), Alanine(790), and a-Amino-n-butyric acid (270). The numbers are the relative math proportion. All the others were less than 100 - the next most prevalent was 8(alpha)-Amino-n(gamma)-butyric acid with a proportion of 74. In my next post I will go into detail on just those 4 amino acids:
