Final answer:
Molecules that can move through the nuclear envelope include ions, small non-charged molecules, and RNA, with larger molecules like proteins requiring specialized proteins to assist in their transport. The nuclear pores facilitate selective and active transport, critical for cellular function.
Step-by-step explanation:
The nuclear envelope is a double-membrane structure that encloses the nucleus, separating its contents from the cellular cytoplasm. The nuclear envelope is equipped with nuclear pores which are protein-lined channels allowing the selective movement of substances. These pores regulate the transport of ions, molecules, and RNA between the nucleoplasm and the cytoplasm.
Not all molecules can move freely through the nuclear envelope. Small, non-charged molecules such as oxygen, carbon dioxide, and water can pass through cell membranes unaided, but charged or larger molecules require assistance. In the context of the nuclear envelope, large proteins, as well as RNA molecules necessary for protein synthesis and genetic material maintenance, move through the pores with the help of special proteins.
This selective transport is critical for the function of the cell, as it ensures that essential materials, such as ribosomes produced in the nucleolus, can be exported to the cytoplasm where they aid in protein synthesis. Moreover, the movement of nuclear proteins into the nucleus is an example of active transport, requiring energy in the form of ATP.