Mitochondrial inheritance · USMLE Step 1

Which structural feature of human mtDNA distinguishes it from nuclear DNA?

  1. It is linear and very large
  2. It is circular and contains 37 genes
  3. It is double-stranded RNA
  4. It is identical in size and structure to nuclear chromosomes
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Correct answer: It is circular and contains 37 genes

Human mtDNA is a small, circular, double-stranded genome encoding 37 genes (tRNAs, rRNAs, and a few polypeptides) — in contrast to linear nuclear chromosomes with tens of thousands of genes.

Difficulty: Medium Question 5 of 19

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