Animals obtain carbon by consuming other living things, like plants and other animals. When they eat, they take in carbon compounds, mainly sugars, proteins, and fats. The food undergoes cellular respiration to convert it into energy. This process involves three main stages:
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Glycolysis: Occurs in the cytoplasm, where glucose (C₆H₁₂O₆) is split into two pyruvate molecules, producing some ATP.
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Citric Acid Cycle: The pyruvate enters the mitochondria, where it's further broken down, generating more ATP and releasing carbon dioxide (CO₂) as a waste product.
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Oxidative Phosphorylation: Here, energy-rich molecules (NADH and FADH₂) transfer electrons through a chain, producing a significant amount of ATP. Oxygen combines with hydrogen, forming water and releasing additional CO₂.