Which term refers to the structural and functional unit containing the cell's energy-producing organelles and their own DNA?

Which term refers to the structural and functional unit containing the cell's energy-producing organelles and their own DNA?

• A. Nucleus
• B. Mitochondria
• C. Cytoplasm
• D. Endoplasmic reticulum

Answer: (B)

This question tests recognizing organelles that are semi-autonomous and carry their own genetic material, a hallmark of mitochondria. Mitochondria are the cell’s energy factories, housing the machinery that converts nutrients into ATP. They contain circular DNA and their own ribosomes, and they replicate independently of the cell, reflecting their ancient endosymbiotic origin. The inner membrane folds, called cristae, increase surface area for the electron transport chain and ATP production, while the matrix hosts enzymes of the Krebs cycle. In contrast, the nucleus stores genetic material and directs cellular activities but does not perform energy production; the cytoplasm is the fluid where many metabolic processes occur; and the endoplasmic reticulum is involved in protein and lipid synthesis, not ATP generation.

This question tests recognizing organelles that are semi-autonomous and carry their own genetic material, a hallmark of mitochondria. Mitochondria are the cell’s energy factories, housing the machinery that converts nutrients into ATP. They contain circular DNA and their own ribosomes, and they replicate independently of the cell, reflecting their ancient endosymbiotic origin. The inner membrane folds, called cristae, increase surface area for the electron transport chain and ATP production, while the matrix hosts enzymes of the Krebs cycle. In contrast, the nucleus stores genetic material and directs cellular activities but does not perform energy production; the cytoplasm is the fluid where many metabolic processes occur; and the endoplasmic reticulum is involved in protein and lipid synthesis, not ATP generation.