← MCQ Arena
Block 5 — Biochemistry MCQs
SZABMU · 676 MCQs with clinical pearls · Prof Jariya
Practise these MCQs free →
Sections in this szabmu
- Amino Acid Carbon Skeletons — 80 MCQs
- Protein Structure — 33 MCQs
- Hormone Signal Transduction — 31 MCQs
- Infertility — 30 MCQs
- Urea Cycle — 27 MCQs
- Amino Acid Classification — 23 MCQs
- Contraception — 23 MCQs
- Thyroid Hormones — 22 MCQs
- Protein Digestion and Absorption — 21 MCQs
- One Carbon Metabolism — 19 MCQs
- Prion Disease — 16 MCQs
- Collagen — 16 MCQs
- Cortisol — 15 MCQs
- Cushing Syndrome — 14 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]
676 MCQs are arranged to the learning outcomes of this szabmu.
Practise free on MCQ Arena →