foreach my $nucleotide(@nucleotide_array)
                      {
                          chomp $nucleotide;
                                  
                          my($T,$G,$C,$A);
                          #These mutations rates reflect 10^-5 
                              if ($nucleotide eq 'A'){
                                     # $T=.1;$G=.2;$C=.3;$A=.7;
                                      my $score = (int rand(100000))/100000;
                                      if( $score>=00000 && $score<=.00033){ $nucleotide='T';}                       
                                      if( $score>=.000334 && $score<=.00066){ $nucleotide='G';} 
                                      if( $score>=.00067 && $score<=.00099){ $nucleotide='C';} 
                                     # if( $score>=.300 && $score<=1.00){  Do NOTHING      } }
                                  }
                              elsif ($nucleotide eq 'T'){
                                     # $A=.1;$G=.2;$C=.3;$T=.7;
                                      my $score = (int rand(100000))/100000;
                                      if( $score>=00000 && $score<=.000333){ $nucleotide='A';}                       
                                      if( $score>=.00034 && $score<=.00066){ $nucleotide='G';} 
                                      if( $score>=.00067 && $score<=.00099){ $nucleotide='C';} 
                                      #if( $score>=.300 && $score<=1.00){  DO NOTHING      } }
                                  }
                              elsif ($nucleotide eq 'C'){
                                     # $T=.1;$G=.2;$A=.3;$C=.7;
                                      my $score = (int rand(100000))/100000;
                                      if( $score>=00000 && $score<=.00033){ $nucleotide='T';}                       
                                      if( $score>=.00034 && $score<=.00066){ $nucleotide='G';} 
                                      if( $score>=.00067 && $score<=.00099){ $nucleotide='A';} 
                                      #if( $score>=.300 && $score<=1.00){  #No mutation} 
                                  }
                              elsif ($nucleotide eq 'G'){
                                     # $T=.1;$A=.2;$C=.3;$G=.7;
                                      my $score = (int rand(100000))/100000;
                                      if( $score>=00000 && $score<=.00033){ $nucleotide='T';}                       
                                      if( $score>=.00034 && $score<=.00066){ $nucleotide='A';} 
                                      if( $score>=.00067 && $score<=.00099){ $nucleotide='C';} 
                                      #if( $score>=.300 && $score<=1.00){  #No mutation} 
                                  }
                          $new_string= $new_string . $nucleotide;