1. The Krebs cycle, also known as the citric acid cycle or TCA cycle, is a series of chemical reactions used by all aerobic organisms to generate energy. 2. It takes place in the mitochondria and begins with the combination of acetyl-CoA and oxaloacetate to form citrate. 3. The cycle then proceeds through a series of steps where citrate is converted back to oxaloacetate, producing NADH, FADH2, and GTP/ATP in the process. 4. These high-energy molecules (NADH and FADH2) are then used in the electron transport chain to produce ATP, the main energy currency of the cell. 5. The main steps include: formation of citrate, isomerization to isocitrate, oxidative decarboxylation to alpha-ketoglutarate, another oxidative decarboxylation to succinyl-CoA, conversion to succinate, oxidation to fumarate, hydration to malate, and oxidation back to oxaloacetate. 6. The overall chemical equation for one turn of the Krebs cycle is: $$\text{Acetyl-CoA} + 3\,\text{NAD}^+ + \text{FAD} + \text{GDP} + \text{P}_i + 2\,\text{H}_2\text{O} \rightarrow 2\,\text{CO}_2 + 3\,\text{NADH} + 3\,\text{H}^+ + \text{FADH}_2 + \text{GTP} + \text{CoA}$$ 7. This cycle is crucial for cellular respiration and energy production in aerobic organisms.