The cell is the fundamental unit of life, characterized by various structures that perform essential functions. One of the most critical components of eukaryotic cells is the endoplasmic reticulum (ER), which is known for its role in protein synthesis and lipid metabolism. There are two types of endoplasmic reticulum: rough ER, which is studded with ribosomes and is primarily involved in the synthesis of proteins destined for secretion or for use in the plasma membrane, and smooth ER, which lacks ribosomes and is involved in lipid synthesis, detoxification, and calcium ion storage.

In order to analyze cellular function, one must understand the significance of these organelles. For instance, mutations affecting the structure or function of the ER can lead to diseases such as cystic fibrosis or dyslipidemias. This context leads to the following question about cellular structures: