Answer
Large particles--proteins and nucleic acid molecules-- enter and leave the nucleus by active transport that uses the energy of ATP. This is required because the selectivity of the nuclear membranes and the proteins that surround the nuclear pores and act as transporters.
Work Step by Step
The nucleus is surrounded by a double membrane, each of which has a lipid bilayer. There are openings in these membranes forming the so-called nuclear pores, the entrances of which are ringed with protein molecules. Substances pass in and out of the nucleus by one of two methods, dependent on molecular size--diffusion, and active transport Ions and small molecules enter and leave the nucleus by simple diffusion. . However, large proteins and nucleic acid molecules cannot transit the nucleopore by diffusion. Proteins enter the nucleus from the cytosol and RNA molecules leave the nucleus by active transport that in involves recognition and the energy of ATP .
