And eventually, during the process of RNA splicing, these sections are actually removed from that mRNA molecule and only these exons are actually left. Now, what about this segment right over here? So this green segment is known as the transcription start side, and this is where transcription actually begins. So a special protein complex that consists of twelve proteins known as RNA polymerase two bind onto the start side, the transcription start side, and this is where initiation actually takes place. This is where we begin the process of transcription. So this is our transcription start site.