Overall equation for aerobic cellular respirationC₆H₁₂O₆ + 6O₂ → 6H₂O + 6CO₂

The same reaction written with its energy outputC₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP

The reverse summary, photosynthesis6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

ATP yield range printed by OpenStax APaerobic cellular respiration → 36 to 38 ATP

One line that stands for four stages

The summary equation is the reverse of the photosynthesis summary, and OpenStax prints it exactly that way: the reaction that harvests the energy of a sugar molecule in cells requiring oxygen consumes oxygen and releases carbon dioxide as waste. The oxidative phosphorylation source then shows why oxygen matters so much. Electrons from NADH and FADH₂ pass through membrane carriers toward oxygen, the final electron acceptor. That transfer pumps hydrogen ions, builds a gradient and lets ATP synthase generate ATP as protons flow back across the inner mitochondrial membrane.

The ATP number is a range, and that is the honest answer

Textbooks quote different totals, and it is worth knowing the source rather than memorizing one figure. OpenStax Biology for AP Courses states that under aerobic conditions the stages of cellular respiration can generate 36 to 38 ATP. Alberts, on NCBI Bookshelf, gives a lower total, saying about 30 ATP molecules are produced for each molecule of glucose oxidized, against 2 from glycolysis alone. Both are legitimate textbook statements, so this page keeps the figures beside their sources instead of flattening them into one supposedly exact answer.

Where this leads next

The Krebs cycle page is the next stop, because it is where the carbon accounting finishes and where the reduced carriers that power the electron transport chain are actually made. Beside that sits the photosynthesis equation, since the two summaries are written as reverses of one another and exam questions routinely ask students to compare their reactants, products and locations. The mitochondrion is the organelle that hosts stages two through four, which is also why mitochondria appear in both plant and animal cells in the cell comparison pages.

Common mistakes

  • Quoting 38 ATP as a fixed fact. OpenStax Biology for AP Courses gives 36 to 38, while Alberts gives about 30.
  • Dropping oxygen from the equation. Oxygen is the final electron acceptor in aerobic respiration, and water forms at the end of that electron flow.
  • Treating the equation as one reaction. The line summarizes a pathway, while oxidative phosphorylation explains how the largest ATP output is made.

Related concepts

  • Photosynthesis equation: The overall equation for photosynthesis is 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂.
  • Krebs cycle: The Krebs cycle, also called the citric acid cycle or TCA cycle, is an eight-step closed loop in the mitochondrial matrix.
  • Prokaryotic vs eukaryotic cells: All cells share four components: a plasma membrane, cytoplasm, DNA and ribosomes.

Sources