The nuclear envelope is a double membrane structure that surrounds the nucleus of a cell. It consists of two lipid bilayers, known as the inner and outer membranes, which protect the genetic material inside the nucleus. The nuclear envelope also contains nuclear pores, which are protein complexes that regulate the movement of molecules in and out of the nucleus, allowing essential substances like RNA and proteins to pass through. This structure plays a crucial role in maintaining the integrity of the nucleus and separating it from the cytoplasm. The nuclear envelope is essential for processes such as DNA replication and gene expression, ensuring that the cell functions properly and that genetic information is accurately transmitted during cell division.