Tetracycline Targets Bacterial-Like Mitochondrial Ribosomes

Steps:

• Mitochondria evolved from bacteria, featuring circular DNA and 70S ribosomes similar to prokaryotes.
• Tetracycline inhibits protein synthesis by binding to the 30S subunit of 70S ribosomes, preventing translation.
• Human cytoplasmic ribosomes are 80S and unaffected, but mitochondrial 70S ribosomes are targeted.
• Options are evaluated based on tetracycline's mechanism and mitochondrial features.

Why D is correct:

• Tetracycline binds specifically to 70S ribosomes, inhibiting translation; mitochondria contain 70S ribosomes, explaining the functional disruption.

Why the others are wrong:

• A: Cell walls are peptidoglycan structures, not DNA-based; tetracycline does not target wall synthesis.
• B: Translation decodes mRNA, not DNA; circular DNA relates to replication, not translation.
• C: Identical to D, but lacks specificity on mitochondrial 70S ribosomes.

Final answer: D