The part of the cell that contains genetic material is the nucleus. The nucleus is often referred to as the cell's control center because it houses the majority of the cell's DNA, which contains the instructions for cellular function, growth, and reproduction. Encased by a double membrane called the nuclear envelope, it protects the genetic material from damage and regulates the exchange of substances between the nucleus and the cytoplasm. Within the nucleus, DNA is organized into structures called chromosomes, and processes such as transcription and replication occur here, making it essential for life.