George is studying a computer model of a dna molecule, in which the letters a, c, g, and t are listed in a very long sequence. the model includes a total of 2000 genes that are scattered along the full length of the molecule. the genes make up only a small fraction of the molecule. george wants to identify the locations of the genes. which would be the most useful first step to follow? a. divide the model molecule into 2000 segments of equal size. b. identify all of the start codons in the model molecule. c. identify the promoter regions in the model molecule. d. divide the model molecule into three-letter pieces.