Wintery Knight

…integrating Christian faith and knowledge in the public square

Doug Axe explains the chances of getting a functional protein by chance

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

Here’s a clip from Illustra Media’s new ID DVD “Darwin’s Dilemma”, which features Doug Axe and Stephen Meyer (both with Ph.Ds from Cambridge University).

I hope you all read Brian Auten’s review of Darwin’s Dilemma! It was awesome.

Related DVDs

Illustra also made two other great DVDs on intelligent design. The first two DVDs “Unlocking the Mystery of Life” and “The Privileged Planet” are must-buys, but you can watch them on youtube if you want, for free.

Here are the 2 playlists:

I also recommend Coldwater Media’s “Icons of Evolution”. All three of these are on sale from Amazon.com.

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2 Responses

  1. […] a stimulus to such, let us next note how the bloggist Wintery Knight has given an interesting summary of the challenges involved if a chance-dominated process is invoked for a hypothetical 100-AA […]

  2. […] (This Explains Everything, 18-20), but he is unwilling to use the same logic with respect to the probability of securing a functional protein subsequent to the Big Bang.  I’m guessing Dawkins would […]

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