Final answer:
The citric acid cycle, taking place in the mitochondrial matrix of eukaryotes, processes acetyl-CoA to produce NADH, FADH₂, CO₂, and ATP (or GTP), with the latter being created by substrate-level phosphorylation. The cycle regenerates oxaloacetate to continue the process and plays a key role in cellular respiration, especially aerobic respiration.
Step-by-step explanation:
The citric acid cycle, also known as the Krebs cycle, is a crucial metabolic pathway that takes place in the mitochondrial matrix of eukaryotic cells and within the cytoplasm of prokaryotes. The citric acid cycle begins with the combination of acetyl-CoA and oxaloacetate to form citric acid. During one turn of the citric acid cycle, which is necessary to process one molecule of acetyl-CoA, the following molecules are produced: two molecules of CO₂, three molecules of NADH, one molecule of FADH₂, and one molecule of ATP (or GTP) through substrate-level phosphorylation. The cycle requires two turns to fully process the carbon from one glucose molecule. By regenerating oxaloacetate, the cycle is prepared to repeat. Thus, the citric acid cycle plays a vital role in energy production, especially in the presence of oxygen, by producing high energy carriers that feed into the electron transport chain. From a summary perspective, the inputs to the cycle include acetyl-CoA and oxygen, while the outputs include ATP (or GTP), NADH, FADH₂, and CO₂. These steps are a series of redox, hydration, and decarboxylation reactions, each catalyzed by a specific enzyme, which release energy captured in energy carriers and expel CO₂ as a waste product.