MCAT® ExamBiological and Biochemical Foundations of Living SystemsMedium
A patient is diagnosed with a genetic disorder characterized by the inability to properly break down long-chain fatty acids, leading to their accumulation in cells, particularly in the liver and brain. Which cellular organelle is most likely dysfunctional in this patient?
- ALysosomes
- BMitochondria
- CPeroxisomes
- DEndoplasmic Reticulum
Show answer & explanationAnswer & explanation
Correct answer: C. Peroxisomes
The breakdown of long-chain fatty acids is a primary function of peroxisomes, which perform beta-oxidation. The accumulation of these fatty acids due to an inability to break them down correctly points directly to a dysfunction in this organelle. While mitochondria are involved in fatty acid metabolism, peroxisomes handle the initial breakdown of very long-chain fatty acids.
Why the other options are wrong
- A. Lysosomes are primarily involved in the degradation of cellular waste and macromolecules, not specifically long-chain fatty acids.
- B. Mitochondria are involved in ATP production and some fatty acid oxidation, but peroxisomes are key for long-chain fatty acid breakdown.
- D. The Endoplasmic Reticulum is involved in protein synthesis, lipid synthesis, and detoxification, not primary fatty acid breakdown.
Peroxisome Function
Peroxisomes are small, membrane-bound organelles that contain oxidative enzymes. Their primary functions include the breakdown of very long-chain fatty acids, detoxification of harmful substances, and synthesis of certain lipids.
- Contain oxidative enzymes (e.g., catalase)
- Perform beta-oxidation of very long-chain fatty acids
- Detoxify harmful compounds
- Involved in plasmalogen synthesis
Memory trick: My Little Peroxide Detoxifies.