Amino Acids & Proteins MCAT Practice Question
A patient presents with a mutation in the gene encoding glycine-rich collagen, where 15% of all glycine residues are replaced with alanine. Glycine is the smallest amino acid with only a hydrogen as its side chain. Why is this mutation particularly severe for collagen structure?
Answer choices
- AAlanine cannot form hydrogen bonds, destabilizing collagen's triple helix
- BThe mutation prevents collagen from assembling into fibrils outside the cell
- CAlanine's charge distribution interferes with collagen cross-linking
- DThe bulkier alanine side chains cannot fit in the crowded interior of the collagen triple helixCorrect answer
- EAlanine residues are hydrophobic and repel the aqueous collagen environment
- FAlanine lacks the ability to stabilize the polyproline II helix conformation required for collagen triple helix formation
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