The termination sequence, which follows the promoter and coding region, is the last region of the gene. This region is not typically modified to alter gene expression. However, during transcription the termination sequence signals to the RNA polymerase molecule that it has reached the end of the gene and should stop transcribing. If this region were not present, RNA polymerase would continue down the chromosome to more of the genes.
This would result in the expression of other genes and the production of their proteins which may not be needed. For example, although finger cells have eyeball genes in them, they do not produce all of the eyeball proteins because they are not needed in your fingers. Finger cells only make proteins needed by the fingers.
The animation below shows the three gene coding regions. This is the fourth of a series of seven animations that detail the process of crop genetic engineering. To begin at the beginning, see Overview of Crop Genetic Engineering.
*This animation has no audio.*