DNA (Deoxyribonucleic acid) is present in the nucleus which contains the genetic information of an organism. Nucleus is necessary for whole the process of cell division and initiation. During cell division DNA plays a most important role carrying of genetic information of old cell to the newly synthesized cells, which only occurs during cell division.
All processes like replication and transcription needs enzymes which are normally found in the nucleus. So, for the protection of DNA keeping DNA within the nucleus and do not cross the nuclear membrane. If DNA is floating in the cytoplasm than DNA can not be transcribed its information into RNA and this process is known as transcription process (DNA into RNA).
