The lipids and proteins constituting the cell membrane are synthesized in the endoplasmic reticulum (ER). Specifically, the lipids are predominantly synthesized in the smooth endoplasmic reticulum (SER) , while the proteins are synthesized by the ribosomes attached to the rough endoplasmic reticulum (RER). The RER synthesizes membrane proteins during translation with ribosomes attached to its membrane, and the SER synthesizes the lipids such as phospholipids necessary for the membrane's structure. These newly synthesized molecules are then transported to the cell membrane and other destinations within the cell.
