The nuclear envelope surrounds the nucleus with a double membrane with multiple pores. The pores regulate the passage of macromolecules like proteins and RNA, but permit free passage of water, ions, ATP and other small molecules.he nucleus of a eukaryotic cell contains the DNA, the genetic material of the cell. The DNA contains the information necessary for constructing the cell and directing the multitude of synthesis tasks performed by the cell in the process of life and reproduction.