A cell is unable to synthesize lipids. Which of its cell organelles might be defective?

The smooth endoplasmic reticulum (SER) is the primary site for the synthesis of lipids, including fatty acids, phospholipids, and steroid hormones [1]. Unlike the rough ER, which is studded with ribosomes for protein synthesis, the SER lacks ribosomes and contains enzymes that catalyze the production of lipids from basic building blocks like glycerol and cholesterol. It is also responsible for the synthesis of phospholipids used in cellular membranes. If a cell is unable to synthesize lipids, the SER is the organelle most likely to be defective. In contrast, Golgi bodies are involved in protein modification and shipping [2], lysosomes handle intracellular digestion and recycling [2], and mitochondria are primarily responsible for energy production in the form of ATP [2]. Therefore, the SER's specialized role in lipid production makes it the critical component for this metabolic function [2].

Sources

1. [1] https://www.sciencedirect.com/topics/medicine-and-dentistry/smooth-endoplasmic-reticulum
2. [2] https://www.khanacademy.org/science/biology/structure-of-a-cell/tour-of-organelles/a/the-endomembrane-system