Question 745 of 782

Which organelle is primarily responsible for producing ATP through cellular respiration in eukaryotic cells?

  • Ribosome
  • Mitochondrion
  • Endoplasmic reticulum
  • Golgi apparatus

Correct Answer: B

Explanation
Correct Option: B. Mitochondrion Detailed Explanation:
  1. Role of Mitochondria in Cellular Respiration:
  2. Mitochondria are often referred to as the "powerhouses" of the cell because they are the primary site for ATP (adenosine triphosphate) production through the process of cellular respiration.
  3. Cellular respiration is a series of metabolic reactions that convert biochemical energy from nutrients into ATP, which is used as a source of chemical energy for various cellular processes.
  4. Process of ATP Production:
  5. The process of cellular respiration occurs in several stages: Glycolysis, the Krebs cycle (also known as the citric acid cycle), and the Electron Transport Chain (ETC).
  6. Glycolysis occurs in the cytoplasm and breaks down glucose into pyruvate, producing a small amount of ATP and NADH.
  7. The Krebs cycle takes place in the mitochondrial matrix, where pyruvate is further broken down, releasing carbon dioxide and transferring high-energy electrons to carrier molecules (NADH and FADH2).
  8. The Electron Transport Chain occurs in the inner mitochondrial membrane, where the high-energy electrons from NADH and FADH2 are transferred through a series of proteins. This process creates a proton gradient across the membrane, which drives ATP synthesis through a process called oxidative phosphorylation.
  9. Why Other Options Are Incorrect:
  10. A. Ribosome: Ribosomes are the sites of protein synthesis, where amino acids are assembled into proteins based on the instructions from mRNA. They do not produce ATP and are not involved in cellular respiration.
  11. C. Endoplasmic Reticulum (ER): The ER is involved in the synthesis of proteins (rough ER) and lipids (smooth ER), as well as the transport of these molecules within the cell. While it plays a crucial role in cellular function, it does not produce ATP.
  12. D. Golgi Apparatus: The Golgi apparatus is responsible for modifying, sorting, and packaging proteins and lipids for secretion or delivery to other organelles. Like the ER and ribosomes, it does not participate in ATP production.
Summary of Key Points:
  • Mitochondria are the primary organelles for ATP production in eukaryotic cells through cellular respiration.
  • Cellular respiration involves glycolysis, the Krebs cycle, and the electron transport chain, all of which occur in or around mitochondria.
  • Other organelles like ribosomes, the endoplasmic reticulum, and the Golgi apparatus have distinct functions unrelated to ATP production.
Revision Summary:
  • Mitochondria are the "powerhouses" of the cell, producing ATP.
  • Cellular respiration consists of glycolysis, the Krebs cycle, and the electron transport chain.
  • Ribosomes, ER, and Golgi apparatus do not produce ATP; they have different cellular functions.
  • Understanding the role of mitochondria is crucial for grasping energy metabolism in cells.
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