Advanced Placement (AP) Biology Practice Exam

Which organelle is involved in the synthesis of lipids and detoxification of drugs?

1. Rough ER

2. Smooth ER

3. Nucleus

4. Peroxisome

The correct answer is: Smooth ER

The smooth endoplasmic reticulum (Smooth ER) is the organelle primarily responsible for the synthesis of lipids and the detoxification of drugs. Unlike its counterpart, the rough endoplasmic reticulum, which is studded with ribosomes and primarily involved in protein synthesis, the smooth ER lacks ribosomes and instead focuses on lipid metabolism. In addition to lipid synthesis, the smooth ER plays a crucial role in detoxifying harmful substances, particularly in liver cells, where it modifies and helps eliminate toxins. This detoxification process ensures that potentially harmful compounds are converted into more manageable forms that can be excreted from the body. The presence of Smooth ER can vary significantly between different cell types based on their metabolic demands, with cells engaged in extensive lipid metabolism showing a greater abundance of this organelle. Therefore, its involvement in both lipid synthesis and drug detoxification makes the smooth endoplasmic reticulum the correct answer to the question.