Eukaryotic Cellular Respiration Pathway — a labelled NEET Biology diagram with a definitions lexicon.
Eukaryotic Cellular Respiration Pathway Labelled parts: Glycolysis, Cytoplasm, Glucose, Pyruvate, Net gain: 2 ATP + 2 NADH, Krebs cycle, Mitochondrial matrix, Oxaloacetate (OAA), Citrate, Malate, Succinate, Succinyl-CoA, α-Ketoglutarate, Link reaction, CoA, Acetyl-CoA, Produces: 2 NADH, Electron transport system, Chemiosmosis, Inner mitochondrial membrane, NADH, FADH₂, O₂, H⁺ gradient, ATP synthase, Oxidative phosphorylation, Per glucose: 6 NADH + 2 FADH₂ + 2 ATP (GTP) + 4 CO₂, Total ATP: about 30-32 ATP in eukaryotes. Also known as the Citric Acid Cycle, this metabolic pathway occurs in the mitochondrial matrix. It completes the oxidation of acetyl-CoA, generating high-energy electron carriers (NADH and FADH₂) for oxidative phosphorylation. FYI: The primary function of the Krebs cycle is not to produce ATP directly, but to generate reducing equivalents (NADH and FADH₂) that fuel the electron transport chain. This reaction links glycolysis (cytosol) and the Krebs cycle (mitochondrial matrix). Pyruvate, the end product of glycolysis, is converted to Acetyl-CoA by the enzyme pyruvate dehydrogenase complex. FYI: The conversion of pyruvate to Acetyl-CoA releases one molecule of CO₂ and generates one molecule of NADH per pyruvate molecule. A four-carbon dicarboxylic acid that serves as a key intermediate in the Citric Acid Cycle (Krebs Cycle). It condenses with acetyl-CoA to form citrate. FYI: OAA is regenerated at the end of the Krebs cycle, allowing the cycle to continue, and it is crucial for gluconeogenesis. Citrate is a tricarboxylic acid (TCA cycle intermediate) formed by the condensation of Acetyl-CoA and oxaloacetate. It is the first molecule to enter the Krebs cycle. FYI: The condensation of Acetyl-CoA and oxaloacetate to form citrate is catalyzed by the enzyme citrate synthase. It is a key intermediate in the Krebs cycle, formed from citrate and subsequently converted to succinyl-CoA. This step involves the oxidative decarboxylation of the molecule. FYI: The conversion of α-ketoglutarate to succinyl-CoA requires the coenzyme B vitamins, specifically thiamine pyrophosphate (TPP). Acetyl-CoA is a two-carbon molecule derived from the breakdown of carbohydrates, fats, and proteins. It serves as the primary entry molecule into the Krebs cycle. FYI: Acetyl-CoA is formed in the mitochondrial matrix and is crucial for initiating the entire aerobic respiration process. This system, located on the inner mitochondrial membrane, uses the energy from NADH and FADH₂ to pump protons (H⁺) into the intermembrane space. The resulting proton gradient drives ATP synthesis via ATP synthase. FYI: Oxygen (O₂) is the final electron acceptor at the end of the electron transport chain, forming water (H₂O).