Domains of Life; Prokaryotic vs. Eukaryotic Cells

ID #1490

Are the nuclear envelope and RER/SER the same? I heard that we say nuclear envelope because they are made of two parts. Does two parts mean rough ER+smooth ER?

If you look closely at what separates the nucleus from the cytoplasm (and we will, in time) you'll see that what we call the nuclear envelope is actually two distinct biological membranes, or lipid bilayers.  There's an outer bilayer and an inner bilayer.  What you'll also notice if you look close enough is that the outer nuclear membrane is continuous with the membrane system that we call the ER, both RER and SER.  Their surfaces are continuous, even though functionally speaking, different things are happening in the nucleus than in the ER.  The most important thing to clear up from your question is that the SER does NOT come from one of the nuclear membranes and the RER from the other -- that's NOT the way it happens.  The RER just typically lies closer to the nucleus, and the SER typically lies further away from the nucleus, with no ribosomes bound to it.

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