Final answer:
The ER's problem of lipid production on the cytosolic side is corrected by lipid-transfer enzymes, ensuring balanced lipid distribution. The ER has a smooth and rough type, and peripheral proteins from the ER lumen end up outside the plasma membrane.
Step-by-step explanation:
The endoplasmic reticulum (ER) is essential for the synthesis and transport of proteins and lipids in a cell. A problem that can occur is the asymmetric production of lipids on the cytosolic side of the ER's membrane, which is resolved by enzymes that transfer some of the newly-made lipids to the lumenal side, ensuring even distribution within the lipid bilayer of the membrane. The ER has two types: smooth endoplasmic reticulum (SER) associated with lipid biosynthesis, carbohydrate metabolism, and detoxification; and rough endoplasmic reticulum (RER), which contains ribosomes for protein synthesis. Peripheral membrane proteins synthesized in the lumen of the ER will end up outside the plasma membrane because they are transported via transport vesicles that fuse with the Golgi apparatus, get modified, and then are directed to the plasma membrane with the correct orientation.