USMLE Step 1 Quiz
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BIOCHEMISTRY
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A 7-year-old boy presents with easy bruising, recurrent fractures, and blue sclerae. A diagnosis of osteogenesis imperfecta is made, caused by a mutation in a gene for type I collagen. An essential step in collagen synthesis is the hydroxylation of proline and lysine residues, a process that requires ascorbic acid (vitamin C).
This specific post-translational modification is critical for which of the following steps in collagen biosynthesis?
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