Mitochondrial inheritance · USMLE Step 1

Which of the following is a possible mechanism by which paternal mitochondria are excluded from inheritance in humans?

  1. Paternal mtDNA integrates into nuclear DNA right after fertilization
  2. Sperm mitochondria are tagged (e.g. by ubiquitin) and destroyed
  3. The egg cell selectively rejects all female mitochondria
  4. mtDNA recombination erases the paternal sequences
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Correct answer: Sperm mitochondria are tagged (e.g. by ubiquitin) and destroyed

After fertilization, paternal mitochondria are typically tagged (e.g. via ubiquitin) and eliminated, ensuring that mtDNA comes almost exclusively from the mother.

Difficulty: Medium Question 8 of 19

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