Answer:
The nature of genes made them be divided into exons, introns and different regulatory sequences
Step-by-step explanation:
The amount of genetic information that is under a gene structure have different roles in order to be correctly read. When a mRNA is produced from a certain gene, some regions from the complete structure of a gene might not be transcribed into a mRNA, and therefore won't be expressed into a protein. One of the main reasons of the smaller size in number of base pairs is because some of those lost regions on the DNA structure are responsible to be regulatory sequences and so, those sequences are not related with the final structure the mRNA and subsequently the protein structure. Some of those regulatory regions are related with the speed of transcription, for instance.