MCAT Biology Question 5: Answer and Explanation
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Question: 5
5. Mitochondrial DNA is:
circular.
self-replicating.
single-stranded.
- A. I only
- B. II only
- C. I and II only
- D. I, II, and III
Correct Answer: C
Explanation:
Mitochondria are thought to have evolved from an anaerobic prokaryote engulfing an aerobic prokaryote and establishing a symbiotic relationship; therefore, mitochondrial DNA, or mDNA, is likely to be similar to bacterial DNA. Both mDNA and bacterial DNA are organized into a single circular chromosome of double-stranded DNA that can replicate during binary fission. Therefore, Statements I and II are correct, while Statement III is incorrect.