proteins

Dear Readers, This post continues directly from Part 2. Second, the authors assume that, in the absence of phenotypic mutations, the first genotypic mutation would be strictly neutral. That is, the selection coefficient for the first mutation is very, very close to zero. It turns out that this is a critical feature. If the first mutation were slightly positive itself (without considering look-ahead) then it could be selected on its own, and the look-ahead effect makes little difference. On the other hand, if the first mutation is slightly negative (including look-ahead), then it will not be positively selected and, again, the effect makes essentially no difference. It is only in a very restricted range of selection coefficients that any significant influence will be Read More ›

Dear Readers, This post continues directly from Part 1. Koonin is clearly very impressed with the new paper, which he calls “brilliant” and “a genuinely important work that introduces a new and potentially major mechanism of evolution…” His enthusiasm is a good indication that the problem is a major one, and that no other papers exist which deal effectively with it. So what is the paper (a theoretical, mathematical-modeling study) about?  When a mutationless gene is transcribed and translated into a protein, errors can creep in. It turns out that these error rates are much higher than for copying DNA. Using published mutation rates, Whitehead et al (2008) estimate that 1 in 10 standard-sized proteins will contain an error; that is, they Read More ›