Humber Admissions Practice Test

The nuclear membrane, also known as the nuclear envelope, is the structure that surrounds and protects the nucleus of a cell. This double-layered membrane is crucial for maintaining the integrity of the genetic material contained within the nucleus. It has pores that regulate the movement of molecules between the nucleus and the cytoplasm, allowing for the selective exchange of substances such as RNA and proteins. This selective permeability is essential for processes like gene expression and the regulation of cellular functions.

The other structures mentioned do not directly surround the nucleus. The cytoplasm is the jelly-like substance within the cell that contains various organelles, while the plasma membrane encases the entire cell, separating its contents from the external environment. Nucleoplasm refers to the viscous fluid inside the nucleus itself, where the chromatin and nucleolus are suspended. Each of these plays different roles in cellular function but does not provide the nuclear protection and regulation that the nuclear membrane offers.