Peroxisomes—structure and function Which statements about peroxisomes are correct?
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AThey have a single boundary membrane
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BThey contain oxidases for fatty acid and amino acid degradation
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CTheir reactions generate hydrogen peroxide, which is toxic to cells
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DAll of the above
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ENone of the above
Answer
Correct Answer: All of the above
Explanation
Introduction / Context:Peroxisomes are small, single-membrane organelles that handle oxidative metabolism, particularly very-long-chain fatty acid oxidation and detoxification reactions.
Given Data / Assumptions:
- Peroxisomes possess a single lipid bilayer (unlike mitochondria or nuclei with double membranes).
- They house oxidases and catalase.
- Oxidative reactions yield hydrogen peroxide (H2O2), a reactive oxygen species.
Concept / Approach:Evaluate each statement against textbook features of peroxisomes: single membrane, oxidative catabolism, and H2O2 production followed by detoxification via catalase.
Step-by-Step Solution:Confirm boundary: peroxisomes are bounded by a single membrane.Confirm metabolism: contain enzymes for β-oxidation (organism-dependent spectrum) and amino acid oxidases.Confirm byproduct: H2O2 is generated and decomposed by catalase to water and oxygen.All three statements are true, so “All of the above” applies.
Verification / Alternative check:Peroxisomal disorders (for example, Zellweger spectrum) disrupt these functions, underscoring the organelle’s roles.
Why Other Options Are Wrong:
- None of the above: Contradicted by well-established cell biology.
Common Pitfalls:Confusing peroxisomes with lysosomes or mitochondria; mixing single vs double membranes.
Final Answer:All of the above.