Editing Cell Theory and Architecture (section)

=== The Nucleus and Endomembrane System ===

* '''Nucleus:''' The defining feature of the eukaryote. It houses the linear DNA genome, bounded by a double-membrane structure called the nuclear envelope, which contains pores regulating the transport of molecules (like mRNA).
* '''Endoplasmic Reticulum (ER):''' An extensive network of membranous tubules and sacs.
** '''Rough ER:''' Studded with ribosomes (80S), focusing on the synthesis and folding of proteins destined for membranes or secretion.
** '''Smooth ER:''' Lacks ribosomes; functions in lipid synthesis, calcium storage, and cellular detoxification.
* '''Golgi Apparatus:''' The cell's sorting and shipping center. It receives proteins and lipids from the ER, modifies them, and packages them into vesicles for targeted delivery.