Axe: A random gene would specify a random sequence of amino acids, which would flop around without folding. Chains like that are rapidly broken back down into amino acids to keep them from interfering with cellular processes. Very special amino acid sequences are needed for protein chains to fold into stable structures.
Nelson: “… it is only possible to scratch the surface of evolutionary history—only those proteins which diverged relatively recently remain similar enough to compare with confidence. The deepest questions about the origins of novel gene families remain shrouded in mystery.”
Researchers: “The historical record of a big bang describing the evolutionary patchwork of proteins provides new tools to understand protein makeup. “
A friend writes to draw our attention to this sentence: “Life met this challenge by evolving molecular chaperones that can minimize protein misfolding and aggregation, even under stressful out-of-equilibrium conditions favoring aggregation.” “Life” is a busy little bee, no? If this were not evolutionary biology, we would talk in terms of purpose and design. Oh but, whoops, they do talk in terms of purpose and design. But none dare call it that.
xcerpt: Putting the probabilities together means adding the exponents. The probability of getting a properly folded chain of one-handed amino acids, joined by peptide bonds, is one chance in 10^74+45+45, or one in 10^164 (Meyer, p. 212). This means that, on average, you would need to construct 10^164 chains of amino acids 150 units long to expect to find one that is useful.
We are told by many philosophers that life came to exist on Earth purely by chance. How likely is that, given the intricacy of the machinery that governs our bodies, such that someone needs to design AlphaFold to figure it out?
Remember when everything you ever were or would be was
in your DNA? Now it’s proteins.
From Catherine Offord at the at The Scientist: In one recent project, for example, Schroeter and her advisor Mary Schweitzer extracted and analyzed collagen peptides from just 200 mg of an 80-million-year-old fossil of a Cretaceous-era herbivore, Brachylophosaurus canadensis, excavated in Montana. The amino acid sequences of those peptides, published last year, placed the dinosaur on Read More…
Can protein folding complexity be formed by stochastic processes? With 14 intermediate steps? JILA Team Discovers Many New Twists in Protein Folding Biophysicists at JILA have measured protein folding in more detail than ever before, revealing behavior that is surprisingly more complex than previously known. . . . They fold into three-dimensional shapes that determine Read More…
“The grammar of DNA might be even more sophisticated than we imagined . . .It could be that all codons could be start codons”
A frequently made claim in the scientific literature is that protein domains can be readily recombined to form novel folds. In Darwin’s Doubt, Stephen Meyer addresses this subject in detail (see Chapter 11). Over the course of this article, I want to briefly expand on what was said there. Defining Our Terms Before going on, it Read More…
What say we copyright the expression “than previously thought”?