aerobic | Aerobic processes require oxygen to produce energy. Oxygen acts as the final electron acceptor in cellular respiration. They generate large amounts of ATP (e.g., aerobic respiration).
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anaerobic | Anaerobic processes occur without oxygen. Energy is produced through pathways like fermentation. They generate less ATP compared to aerobic processes.
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Energy transfer/conversion | Energy transfer moves energy from one form to another (e.g., chemical to kinetic). In cells, chemical energy from glucose is converted into ATP. This process powers cellular activities.
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mitochondria | Mitochondria are double-membrane organelles responsible for ATP production. They are the site of the Krebs cycle and oxidative phosphorylation. The inner membrane contains proteins for the electron transport chain (ETC).
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glycolysis | Glycolysis breaks down glucose into 2 pyruvate molecules. It occurs in the cytoplasm and produces 2 ATP and 2 NADH. It is an anaerobic process and the first step in cellular respiration.
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pyruvate | Pyruvate is a 3-carbon product of glycolysis. It enters the mitochondria during aerobic respiration for conversion to acetyl-CoA. In anaerobic conditions, pyruvate is converted into lactate or ethanol.
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NAD+/NADH | NAD+ is an electron carrier that becomes NADH upon gaining electrons. NADH transports electrons to the electron transport chain for ATP production. It is regenerated during fermentation or oxidative phosphorylation.
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FAD/FADH2 | FAD is an electron carrier that becomes FADH2 when reduced. FADH2 donates electrons to the electron transport chain at a lower energy level. It is produced during the Krebs cycle.
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acetyl CoA | Acetyl CoA is a 2-carbon molecule formed from pyruvate. It enters the Krebs cycle, combining with oxaloacetate to form citrate. It is central to metabolism in aerobic respiration.
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Krebs/Citric Acid cycle | The Krebs cycle occurs in the mitochondrial matrix. It oxidizes acetyl CoA, producing NADH, FADH2, ATP, and CO2. It supplies electrons to the electron transport chain.
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electron | Electrons carry energy transferred during redox reactions. They flow through the electron transport chain to power ATP synthesis. Electrons are ultimately accepted by oxygen in aerobic respiration.
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glucose | Glucose is a 6-carbon sugar that is the primary energy source for cells. It is broken down in glycolysis to release energy. Its complete oxidation yields CO2, H2O, and ATP.
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electron transport chain [ETC] | The ETC is a series of protein complexes in the inner mitochondrial membrane. It transfers electrons, driving H+ across the membrane to form a gradient. It powers ATP synthesis through chemiosmosis.
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