Protein Chemistry and Metabolism MCQs

342 MCQs with clinical pearls · MBBS Biochemistry · Prof Jariya

Topics covered (31)

Amino Acid Carbon Skeletons — 79 MCQs
Protein Structure — 33 MCQs
Urea Cycle — 27 MCQs
Amino Acid Classification — 23 MCQs
Protein Digestion and Absorption — 21 MCQs
One Carbon Metabolism — 19 MCQs
Prion Disease — 16 MCQs
Collagen — 16 MCQs
Amino Acid Transport — 12 MCQs
Protein Metabolism — 10 MCQs
Homocysteine Metabolism — 7 MCQs
Amino Acid Chemistry — 7 MCQs
Amino Acid Disorders — 7 MCQs
Alzheimer's Disease — 6 MCQs
Plasma Proteins — 6 MCQs
Elastin — 6 MCQs
Protein Classification — 5 MCQs
Phenylketonuria — 5 MCQs
Homocystinuria — 5 MCQs
Protein Chemistry and Metabolism — 5 MCQs
Axial Ratio — 4 MCQs
Protein Techniques — 4 MCQs
Protein Misfolding Disorders — 3 MCQs
Amyloidoses — 3 MCQs
Clinical Protein Scenarios — 3 MCQs
Protein Folding and Misfolding — 2 MCQs
Nitrogen Balance — 2 MCQs
Protein Degradation — 2 MCQs
Branched-Chain Amino Acid Disorders — 2 MCQs
Haemoglobin — 1 MCQs
Coenzymes and Cofactors — 1 MCQs

Sample MCQs with clinical pearls

A 87-year-old man with Alzheimer's disease has amyloid plaques forming due to faulty APP cleavage. Which enzyme is responsible for the abnormal cleavage producing toxic fragments over the past 3 years?

A) Alpha secretase

B) Beta secretase ✔

C) Delta secretase

D) Gamma secretase

E) Sigma secretase

BETA secretase (BACE1) cleaves APP differently from alpha secretase → produces C99 fragment → gamma secretase cleaves C99 → Aβ42 (42 amino acid peptide) → beta pleated sheet → insoluble aggregates → neuritic plaques in extracellular space of hippocampus and cortex → Alzheimer's disease. When ALPHA secretase was active (normal) → non-amyloidogenic pathway → no plaques. 📹 [VIDEO LINK]

Which of the following prion diseases is linked to ritualistic cannibalism?

A) Fatal familial insomnia

B) Gerstmann-Sträussler-Scheinker syndrome

C) Kuru ✔

D) Scrapie

E) Variant CJD

Kuru = prion disease found among the Fore people of Papua New Guinea — transmitted by ritualistic cannibalism (eating brain of deceased relatives during mourning ceremonies). Women and children most affected. Cerebellar signs predominate (kuru = trembling in Fore language). Elimination of cannibalism led to disappearance of Kuru. First human prion disease identified — led Carleton Gajdusek to Nobel Prize 1976. 📹 [VIDEO LINK]

Normal prion protein (PrPc) and infectious prion protein (PrPsc) have identical amino acid sequences but differ in which of the following?

A) Glycosylation pattern

B) Lipid anchor type

C) Primary structure

D) Three-dimensional conformation ✔

E) Transcriptional modification

PrPc and PrPsc have IDENTICAL PRIMARY STRUCTURES (same amino acid sequence, same gene PRNP) — they differ ONLY in THREE-DIMENSIONAL CONFORMATION. PrPc = alpha helix rich, protease sensitive, membrane-anchored via GPI anchor. PrPsc = beta sheet rich, PROTEASE RESISTANT, aggregates. Same sequence, completely different properties — this is why prions were so revolutionary and initially so controversial. 📹 [VIDEO LINK]

These are three of 342 MCQs in this section. Every question carries a clinical pearl explaining the reasoning.

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