Protein and DNA evolution: Statistics and combinatorics are the rules of the game

Abstract

Let us assume AVMAYDRYVAIC or MAYDRYVAICCP, most important signature domain of olfactory receptor (OR) gene family assembled in evolution following simplest possible laws of statistics which says the addition of V after A in AVMAYDRYVAIC or addition of A after M are independent events. There are 20 amino acids present in nature so the probability of joint occurrence of such events is 1/400. Therefore for making a contiguous string of AVMAYDRYVAIC or MAYDRYVAICCP, the probability would be 1 out of 2012. Over millions of years of evolution this has certainly happened and that is why we see such a signature sequence in OR1D2, OR1D subfamily member 2 as per "HORDE database":https://senselab.med.yale.edu/ORDB/files/humanorseqanal.html. Now let us assume that another hypothetical protein domain, AKHNARDRIINY has formed in the aforesaid method. In this paper, using rules of combinatorics we show that how genomes and proteomes of distantly related organisms have formed and this is the general rule.