Extracellular Matrix MCQs

68 MCQs with clinical pearls · MBBS Biochemistry · Prof Jariya

Topics covered (13)

Collagen Disorders — 15 MCQs
Collagen Structure — 12 MCQs
AAT Deficiency — 11 MCQs
ECM Proteins — 7 MCQs
Glycosaminoglycans — 6 MCQs
Peroxisomal Disorders — 6 MCQs
Fibrous Proteins — Clinical — 4 MCQs
Collagen — 2 MCQs
Cell Adhesion — 1 MCQs
Basement Membrane — 1 MCQs
ECM Remodelling — 1 MCQs
Proteoglycans — 1 MCQs
Elastin — 1 MCQs

Sample MCQs with clinical pearls

A biochemist studying collagen notes that procollagen is synthesised as a precursor with extra peptides at both ends. These extra peptides are called:

A) Propeptides ✔

B) Signal peptides

C) Telopeptides

D) Tripeptides

E) Zymopeptides

Procollagen = soluble precursor with N and C-terminal propeptides. Propeptides: (1) prevent intracellular fibril assembly, (2) guide correct chain registration. After secretion: procollagen N/C-proteinase cleavage → tropocollagen → fibril assembly → crosslinking by lysyl oxidase → mature collagen.

A 15-year-old OI patient has a mutation replacing glycine in the Gly-X-Y repeat of type I collagen. Which type of side chain replacing glycine would be LEAST likely to disrupt the triple helix?

A) Acidic side chain

B) Bulky side chain

C) Non-polar side chain

D) Polar side chain

E) Small side chain ✔

Glycine has the smallest possible side chain (single H atom) essential to fit inside the cramped triple helix centre. Replacement with any bulky side chain blocks triple helix formation. A small side chain replacement causes least disruption. Severity of OI correlates with bulkiness of substituting amino acid.

A 4-year-old boy with skin hyperextensibility, joint hypermobility, and easy bruising has a collagen type V mutation. Type V collagen is important because it regulates fibrillogenesis of:

A) Collagen type I and III ✔

B) Collagen type II and IV

C) Collagen type II and VI

D) Collagen type III and IV

E) Collagen type IV and VII

Type V collagen nucleates and regulates fibril diameter of type I and III collagen. Collagen V mutation → disorganised type I/III fibrils → weakened skin (hyperextensibility) and joint capsules/tendons (hypermobility) = Ehlers-Danlos Syndrome classic type.

These are three of 68 MCQs in this section. Every question carries a clinical pearl explaining the reasoning.

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