synthesize poteins destined either for incorporation into cell membranes or for export from the cell.
("network within the cytoplasm")
Extensive system of interconnected tubes and parallel membranes enclosing fluid- filled cavities (cisternae)
Rough Endoplasmic Reticulum
External surface is covered with ribosomes
Well developed in most secretory cells, antibody-producing plasma cells, and liver cells -> produce most blood proteins
The cell's "membrane factory" b/c integral proteins and phosholipids that form part of all cellular membranes are manufactured there.
Smooth Endoplasmic Reticulum
Consits of tubules arranged in a looping network
important role in calcium ion storage and release during muscle contraction
Consists of stacked and flattened membranous sacs
: modify, concentrate, and package the proteins and lipids made at the rough ER
Spherical membranous organelles containing acivated digestive enzymes
Can digest almost all kinds of biological molecules
Work best in acidic conditions &are caalled "acid hydrolases"