Answer to Question #159228 in Cell Biology for Allouzi

Question

Both plasma membrane (cell membrane) and nuclear envelop are bilayer.

A large molecule like RNA can pass through which of the above membrane? Explain why.

Answer 1

A large molecule like RNA can pass through nuclear envelope

After mRNA is synthesized by DNA during transcription, the new molecule moves from the nucleus to the cytoplasm, passing through the nuclear membrane through a nuclear pore. Nuclear pore complexes allow the transport of molecules across the nuclear envelope. This is accomplished via "openings" consisting of proteins and known as nuclear pore complexes (NPC).

mRNA molecules can not readily cross the plasma membrane (because they carry an electric charge i.e. ions). They require the help of membrane transport proteins in order for this to occur.