Describe the function of the nuclear envelope.

The nuclear envelope functions primarily as a barrier that regulates the exchange of materials between the nucleus and the cytoplasm. It consists of two lipid bilayers—an inner membrane and an outer membrane—separated by a space called the perinuclear space. Embedded in the nuclear envelope are nuclear pore complexes, which serve as gateways that control the transport of ions, small molecules, and larger proteins and RNA molecules into and out of the nucleus. This selective permeability allows the nucleus to maintain its distinct environment for processes such as DNA replication and RNA synthesis while still facilitating necessary communication and transport with the cytoplasm.

The other options describe functions associated with different cellular structures. The nuclear envelope does not serve as a storage organelle for DNA since DNA is housed within the nucleus itself rather than being stored in the envelope. Additionally, the nuclear envelope is not involved in providing structural integrity to the mitochondria, as mitochondria have their own distinct structure and membranes. Lastly, the process of protein synthesis occurs on ribosomes and in the rough endoplasmic reticulum, rather than within the nuclear envelope. Hence, the nuclear envelope's primary role in regulating material exchange aligns perfectly with the correct answer.