Which of the following is encoded by mitochondrial DNA?

• A. Ribosomal RNA (rRNA) genes
• B. DNA polymerase alpha
• C. Cytochrome b
• D. Histone H1

Answer: (C)

Verified step by step guidance

1. Step 1: Understand that mitochondrial DNA (mtDNA) is a small circular genome found in mitochondria, distinct from nuclear DNA, and it encodes genes essential for mitochondrial function.
2. Step 2: Recall that mtDNA primarily encodes components involved in the mitochondrial electron transport chain and protein synthesis machinery, including some ribosomal RNAs (rRNAs), transfer RNAs (tRNAs), and protein subunits like cytochrome b.
3. Step 3: Recognize that DNA polymerase alpha and histone H1 are nuclear-encoded proteins; DNA polymerase alpha is involved in nuclear DNA replication, and histone H1 is a nuclear chromatin protein, neither of which are encoded by mtDNA.
4. Step 4: Identify that ribosomal RNA (rRNA) genes and cytochrome b are indeed encoded by mitochondrial DNA, as these are critical for mitochondrial ribosome function and electron transport, respectively.
5. Step 5: Conclude that among the options, ribosomal RNA (rRNA) genes and cytochrome b are encoded by mitochondrial DNA, while DNA polymerase alpha and histone H1 are not.