What are the main events of the citric acid cycle?
David Craig
Updated on April 02, 2026
The eight steps of the citric acid cycle are a series of redox, dehydration, hydration, and decarboxylation reactions. Each turn of the cycle forms one GTP or ATP as well as three NADH molecules and one FADH2 molecule, which will be used in further steps of cellular respiration to produce ATP for the cell.
What is the role of the citric acid cycle?
The citric acid cycle, also known as the Krebs cycle or the tricarboxylic acid cycle, is at the center of cellular metabolism, playing a starring role in both the process of energy production and biosynthesis. It finishes the sugar-breaking job started in glycolysis and fuels the production of ATP in the process.
Why is it called the citric acid cycle?
The name citric acid cycle is derived from the first product generated by the sequence of conversions, i.e., citric acid. Malic acid is converted to oxaloacetic acid, which, in turn, reacts with yet another molecule of acetyl CoA, thus producing citric acid, and the cycle begins again.
What is the first step of the citric acid cycle?
The citric acid cycle utilizes mitochondrial enzymes. The first step is fusion of the acetyl group of acetyl-CoA with oxaloacetate, catalyzed by citrate synthase. CoA-SH and heat are released and citrate is produced. Citrate is isomerized by dehydration and rehydration to isocitrate.
Which steps in the citric acid cycle are redox reactions?
After entering the mitochondria, pyruvate dehydrogenase catalyzes pyruvate oxidation to Acetyl-S-Coenzyme A (Ac-S-CoA). Then the Krebs cycle completely oxidizes the Ac-S- CoA. These mitochondrial redox reactions generate CO2 and lot of reduced electron carriers (NADH, FADH2).
What are the key control points within the citric acid cycle?
Within the citric acid cycle itself, the three control points are the reactions catalyzed by citrate synthase, isocitrate dehydrogenase, and the α-ketoglutarate dehydrogenase complex.
What is the overall reaction of the citric acid cycle?
The electron transport chain then generates additional ATPs by oxidative phosphorylation. The citric acid cycle also produces 2 ATP by substrate phosphorylation. The overall reaction for the citric acid cycle is:2acetylgroups+6NAD++2FAD+2ADP+2Piyields4CO2+6NADH+6H++2FADH2+2ATP.
Which process connects glycolysis and citric acid cycle?
The transition reaction connects glycolysis to the citric acid (Krebs) cycle. The transition reaction converts the two molecules of the 3-carbon pyruvate from glycolysis (and other pathways) into two molecules of the 2-carbon molecule acetyl Coenzyme A (acetyl-CoA) and 2 molecules of carbon dioxide.
When the citric acid cycle is complete Where is most of the energy from the initial glucose molecule?
After two rounds of the citric acid cycle, we have completely oxidized one molecule of glucose to CO 2start subscript, 2, end subscript and captured its energy in a series of steps. These products from the citric acid cycle are made in the mitochondria of your cells..
What is the citric acid cycle (Krebs cycle)?
The Citric Acid Cycle is also known as the Krebs Cycle or Tricarboxylic Acid (TCA) Cycle. It is a series of chemical reactions that takes place in the cell that breaks down food molecules into carbon dioxide, water, and energy. Narayanese/Wikimedia Commons.
How is oxaloacetate regenerated in the citric acid cycle?
In the last step of the citric acid cycle, oxaloacetate—the starting four-carbon compound—is regenerated by oxidation of malate. Another molecule of is reduced to in the process. Products of the citric acid cycle
Where does the citric acid cycle occur in mitochondria?
The citric acid cycle occurs in the cristae or membrane folds of mitochondria. Citric Acid Cycle (Krebs Cycle) Definition. The citric acid cycle, also known as the Krebs cycle or tricarboxylic acid (TCA) cycle, is a series of chemical reactions in the cell that breaks down food molecules into carbon dioxide, water, and energy.
How many steps are there in the citric acid cycle?
The citric acid cycle is a closed loop; the last part of the pathway reforms the molecule used in the first step. The cycle includes eight major steps. Simplified diagram of the citric acid cycle.
