Which of the following cellular components is a distinguishing feature of eukaryotic cells compared to prokaryotic cells, and is directly involved in the synthesis of complex carbohydrates and lipids?
Correct: C
While prokaryotes have a plasma membrane, ribosomes (70S), and often a cell wall, they lack the complex internal membrane systems characteristic of eukaryotes. The Smooth Endoplasmic Reticulum (SER) is a unique eukaryotic organelle primarily involved in lipid synthesis (including phospholipids and steroids), detoxification of drugs and poisons, and storage of calcium ions. It also plays a role in carbohydrate metabolism, particularly glycogen breakdown in liver cells. Prokaryotes perform these functions in the cytoplasm or on the plasma membrane, but do not possess a dedicated SER.