Cell Organelles MCQs

72 MCQs with clinical pearls · MBBS Biochemistry · Prof Jariya

Topics covered (10)

Cell Organelles — Clinical Correlations — 28 MCQs
Cell Organelles — Mitochondria — 15 MCQs
Cell Organelles — Lysosomal Storage — 6 MCQs
Cell Cycle and Apoptosis — 5 MCQs
Cell Organelles — MCAD — 4 MCQs
Lysosomal Storage Diseases — 4 MCQs
Cell Organelles — LHON — 3 MCQs
Cell Organelles — Gaucher — 3 MCQs
Protein Trafficking — 3 MCQs
Peroxisome Disorders — 1 MCQs

Sample MCQs with clinical pearls

A 25-year-old woman with fumarate hydratase deficiency develops uterine fibroids and renal cell carcinoma. Accumulating fumarate causes pseudohypoxia. In which cellular compartment does fumarate hydratase normally function?

A) Cytosol

B) Golgi lumen

C) Lysosomal lumen

D) Mitochondrial matrix ✔

E) Peroxisomal matrix

Fumarase (fumarate hydratase) = TCA cycle enzyme in the MITOCHONDRIAL MATRIX. Catalyses fumarate → malate. All TCA cycle enzymes are in the matrix EXCEPT succinate dehydrogenase (inner mitochondrial membrane). Fumarate hydratase mutations cause HLRCC — fumarate accumulates → pseudohypoxia → tumour growth. 📹 [VIDEO LINK]

A 70-year-old man with alcoholic liver cirrhosis has extensive hepatocyte necrosis on biopsy. His hepatocytes are rupturing and releasing cytoplasmic contents into the bloodstream. Which cytosolic marker enzyme would be most elevated in his serum?

A) Acid phosphatase

B) Catalase

C) Cytochrome c oxidase

D) Galactosyl transferase

E) Lactate dehydrogenase ✔

Lactate dehydrogenase (LDH) = marker enzyme for the CYTOSOL. Hepatocyte necrosis → cytoplasmic contents including LDH leak into bloodstream → elevated serum LDH. LDH-5 (liver + skeletal muscle subtype) specifically elevated in liver disease. LDH-1 predominates in MI and haemolysis. 📹 [VIDEO LINK]

A 6-week-old girl with seizures, hypotonia, and elevated plasma very-long-chain fatty acids undergoes liver biopsy. Subcellular fractionation shows that catalase is dispersed throughout the cytosol rather than concentrated in its usual compartment. Which organelle is absent or dysfunctional in this girl?

A) Endoplasmic reticulum

B) Golgi apparatus

C) Lysosome

D) Mitochondria

E) Peroxisome ✔

Catalase = marker enzyme for PEROXISOMES. In Zellweger syndrome (PEX gene mutations): peroxisomes fail to form → catalase synthesised on free ribosomes but cannot be imported → mislocalised to cytosol. This cytosolic displacement of normally peroxisomal catalase is diagnostic of peroxisome biogenesis disorders. 📹 [VIDEO LINK]

These are three of 72 MCQs in this section. Every question carries a clinical pearl explaining the reasoning.

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