Mutation operator

The mutation operator is the second commonly used operator, Mutation brings new traits into a chromosome. The mutation operator eauscs a loeai change in an artificial chromosome. 

Init Pop Initial Fitness Exp/ Copies Actual Copies Mating Pop Crossover Operation Mutation Operation New Fitness... 

Although there are different definitions of the GA move class operator mutate, the purpose of mutate is the same to prevent the population of candidate structures becoming a population of similar candidate structures (to maintain the diversity of the population). Likewise there are also different definitions for the GA move class crossover. In one definition mutate is the process of randomly displacing one ion within a candidate structure and crossover is the process of swapping a random number of ionic coordinates in the simulated DNA of two candidate structures within the current population. Note that in the crossover process the nth variable of one simulated DNA sequence is swapped with the nth variable of the other. 

Figure 29 The genetic operators mutation and crossover in genetic algorithms.

The operator is the site on the chromsome where the lac repressor is thought to bind, thereby inhibiting transcription. The combined length of the promoter operator region is about 100 nucleotides. Operator mutations (o ) result in a decreased ability of the operator to bind repressor and lead to constitutivity, which is the ability to synthesize the products of the operon in the absence of inducer. Levels of constitutive synthesis in o" mutants range from 2 to 30% of wild type, and addition of inducer can increase the enzyme synthesis to levels of the wild-type strain [29],... 

The characteristics of some promoter mutants have been determined. Promoter mutants produce all three of the operon-assodated proteins at a diminished rate. Such mutants are affected in the usual way by inducers and the repressor of the lac operon, indicating that the promoter locus is involved in control processes other than those regulated by the operator and i gene product. Promoter mutations like operator mutations are cis-dominant. 

An interesting property of the operator mutations is that they give rise to different levels of derepression. This means that, if the operator... 

Apply some genetic operators (mutation crossover) to members of the population to create new solutions. 

The last operation, mutation, is performed in the same way that crossover do. Along the chromosome, a gene (binary number), is selected in mutation probability proportion. The gene has its characteristic mutated, 0 to 1 , or vice-versa. 

M. Zacharias, B. A. Luty, M. E. Davis, and J. A. McCammon, /. Molec. Biol., 238, 455 (1994). Combined Conformational Search and Finite-Difference Poisson-Boltzmann Approach for Flexible Docking. Application to an Operator Mutation in the Lambda Repressor-Operator Complex. 

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