Which cellular structure is involved in the synthesis of lipids?

The endoplasmic reticulum (ER) plays a crucial role in the synthesis of lipids within the cell. It is a network of membranes that is continuous with the nuclear envelope and extends throughout the cytoplasm. The ER comes in two forms: rough and smooth.

The smooth endoplasmic reticulum (SER) is particularly important for lipid synthesis. It lacks ribosomes on its surface, which distinguishes it from the rough ER. The SER is involved in the production of phospholipids and cholesterol, which are key components of cellular membranes. Additionally, the SER participates in detoxification processes and metabolism of carbohydrates.

In contrast, the nucleus is primarily responsible for storing genetic information and regulating gene expression, so it does not directly participate in lipid synthesis. Ribosomes are the cellular structures that synthesize proteins by translating messenger RNA, while the Golgi apparatus is involved in modifying, sorting, and packaging proteins and lipids for secretion or use within the cell, but it does not synthesize them.