What is the primary function of the Smooth Endoplasmic Reticulum (Smooth ER)?

The primary function of the Smooth Endoplasmic Reticulum (Smooth ER) is to synthesize lipids. This organelle is characterized by the absence of ribosomes on its surface, distinguishing it from the Rough Endoplasmic Reticulum, which is studded with ribosomes and primarily involved in protein synthesis.

The Smooth ER plays a crucial role in lipid metabolism, including the synthesis of phospholipids and cholesterol, which are essential for cell membrane formation and function. Additionally, it is involved in the synthesis of steroid hormones and detoxification processes. Therefore, the correct choice accurately reflects the Smooth ER's function in lipid production while noting its ribosome-free nature. This specificity in function helps clarify the unique role of the Smooth ER in cellular processes compared to other endoplasmic reticulum types and related cellular structures.