The internal membrane hypothesis

Like the nuclear envelope, it is hypothesized that all of the internal, membrane-bound organelles (rough and smooth endoplasmic reticula, Golgi apparatus, vacuoles, and lysosomes originated from infoldings of the plasma membrane. Evidence that supports this is their membranes are all composed of phospholipids, exactly akin to the plasma membrane. Over time, each of the organelles began to accrue a different suite of molecules and proteins coded by the DNA required to complete their specific intracellular functions.