Which of the following statements is true regarding human mitochondrial diseases?

• A. They only affect the nervous system and do not impact other organs.
• B. They are caused by mutations in chloroplast DNA.
• C. They can be transmitted equally from both parents due to biparental inheritance of mitochondria.
• D. They are often inherited maternally because mitochondria are passed from mother to offspring.

Answer: (D)

Verified step by step guidance

1. Understand the role of mitochondria in human cells: Mitochondria are organelles responsible for energy production through cellular respiration. They contain their own DNA, which is separate from nuclear DNA.
2. Learn about mitochondrial inheritance: Mitochondria are inherited maternally because during fertilization, the egg contributes the majority of cytoplasm, including mitochondria, while the sperm contributes primarily nuclear DNA.
3. Analyze the incorrect statements: Mitochondrial diseases can affect multiple organ systems, not just the nervous system. They are not caused by mutations in chloroplast DNA, as chloroplasts are found in plants, not humans. Mitochondria are not inherited biparentally; they are inherited maternally.
4. Focus on the correct statement: Mitochondrial diseases are often inherited maternally because mitochondria are passed from mother to offspring through the egg cytoplasm.
5. Conclude by emphasizing the importance of understanding maternal inheritance in mitochondrial diseases and how it impacts genetic counseling and disease transmission studies.