Which of the following organelles is responsible for producing ATP in eukaryotic cells, as would be labeled in a cross section of a sheep brain?

• A. Mitochondrion
• B. Golgi apparatus
• C. Lysosome
• D. Nucleolus

Answer: (A)

Verified step by step guidance

1. Understand the function of each organelle listed in the options: The mitochondrion is known as the 'powerhouse of the cell' because it produces ATP (adenosine triphosphate) through cellular respiration. The Golgi apparatus is involved in modifying, sorting, and packaging proteins and lipids. Lysosomes are responsible for breaking down waste materials and cellular debris. The nucleolus is involved in ribosome production.
2. Recall that ATP is the primary energy currency of the cell, and its production is a key function of the mitochondrion. This process occurs through oxidative phosphorylation in the inner mitochondrial membrane.
3. Eliminate the incorrect options based on their functions: The Golgi apparatus, lysosome, and nucleolus do not produce ATP, so they cannot be the correct answer.
4. Focus on the mitochondrion: It contains its own DNA and enzymes necessary for the Krebs cycle and the electron transport chain, which are critical for ATP synthesis.
5. Conclude that the organelle responsible for producing ATP in eukaryotic cells, such as those in a sheep brain, is the mitochondrion.