Bonjour,
C'était juste pour partager avec vous l'extrait d'un blogger américain qui cite les travaux de Doug Axe et d'Anne Gauger (Université de Cambridge, directeur du Biologic Institute), qui ont calculé une approximation de la probabilité de la formation d'une protéine à partir d'éléments simples (attention Anglais) :
I’ve talked about Doug Axe before when I described how to calculate the odds of getting functional proteins by chance.
Let’s calculate the odds of building a protein composed of a functional chain of 100 amino acids, by chance. (Think of a meaningful English sentence built with 100 scrabble letters, held together with glue)
Sub-problems:
BONDING: You need 99 peptide bonds between the 100 amino acids. The odds of getting a peptide bond is 50%. The probability of building a chain of one hundred amino acids in which all linkages involve peptide bonds is roughly (1/2)^99 or 1 chance in 10^30.
CHIRALITY: You need 100 left-handed amino acids. The odds of getting a left-handed amino acid is 50%. The probability of attaining at random only L–amino acids in a hypothetical peptide chain one hundred amino acids long is (1/2)^100 or again roughly 1 chance in 10^30.
SEQUENCE: You need to choose the correct amino acid for each of the 100 links. The odds of getting the right one are 1 in 20. Even if you allow for some variation, the odds of getting a functional sequence is (1/20)^100 or 1 in 10^65.
The final probability of getting a functional protein composed of 100 amino acids is 1 in 10^125. Even if you fill the universe with pre-biotic soup, and react amino acids at Planck time (very fast!) for 14 billion years, you are probably not going to get even 1 such protein. And you need at least 100 of them for minimal life functions, plus DNA and RNA.
Research performed by Doug Axe at Cambridge University, and published in the peer-reviewed Journal of Molecular Biology, has shown that the number of functional amino acid sequences is tiny:
Doug Axe’s research likewise studies genes that it turns out show great evidence of design. Axe studied the sensitivities of protein function to mutations. In these “mutational sensitivity” tests, Dr. Axe mutated certain amino acids in various proteins, or studied the differences between similar proteins, to see how mutations or changes affected their ability to function properly. He found that protein function was highly sensitive to mutation, and that proteins are not very tolerant to changes in their amino acid sequences. In other words, when you mutate, tweak, or change these proteins slightly, they stopped working. In one of his papers, he thus concludes that “functional folds require highly extraordinary sequences,” and that functional protein folds “may be as low as 1 in 10^77.”
The problem of forming DNA by sequencing nucleotides faces similar difficulties. And remember, mutation and selection cannot explain the origin of the first sequence, because mutation and selection require replication, which does not exist until that first living cell is already in place.
But you can’t show that to your friends, you need to send them a video. And I have a video!
A video of Doug Axe explaining the calculation
http://www.youtube.com/watch?v=h38Xi-Jz9yk
I hope you all read Brian Auten’s review of Darwin’s Dilemma! It was awesome.
S'il ne se trompe pas, cela représente (je crois) un obstacle énorme à la théorie de l'évolution, voire insurmontable
(1/10^77, ce qui est supérieur au nombre de secondes écoulées depuis le Big Bang)
Stephen C. Meyer a par la suite repris ses études et l'a étendu à l'apparition d'une protéine "fonctionnelle", pour finalement déterminer que cette probabilité serait en fait égale à 1/10^164, ce qui est supérieur au nombre d'évènements élémentaires qui se sont produits depuis le Big Bang !
Votre avis sur la question ?
Cordialement.
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Envoyé par Kamflow 
), mais aujourd'hui, le passage de l'inerte au vivant est une énigme. 
), cela ne change pas sur le fond des choses.
