How Many ATP Molecules are Produced in Aerobic Respiration

Introduction

The complete oxidation of one glucose molecule during aerobic respiration can theoretically result in 38 ATP molecules. This is only an assumption since all of the routes by which ATP and carbohydrates are used as needed are active at the same time and enzyme activity is regulated by a variety of factors. Organisms convert glucose into a form the cell can use as energy through a process called cellular respiration. The main form of energy used by living things is ATP (adenosine triphosphate).

Cellular Respiration

• The process of cellular respiration involves the oxidation of biological fuels in the presence of an inorganic electron acceptor, such as oxygen, to generate significant amounts of energy that are used to power the major production of ATP.

• The process of converting chemical energy from nutrients into adenosine triphosphate (ATP) in an organism's cells, followed by the release of waste products, is known as cellular respiration.

• During catabolic reactions, which divide large molecules into smaller ones and release energy, respiration takes place. One of the main mechanisms by which a cell releases chemical energy to power cellular activity is respiration. In a series of biochemical steps, some of the redox reactions lead to the overall reaction.

• The slow and controlled release of energy from the series of reactions makes cellular respiration an unusual combustion reaction, despite the fact that it is technically one.

Aerobic Respiration

• In aerobic respiration, oxygen is required for the breakdown of the substance in order to form ATP.

• There are two pathways where the aerobic respiration process is followed: glycolysis and the citric acid cycle.

• In aerobic respiration, the reactant is fully or partially oxidized to form a respected product, Co2, and ATP.

Glycolysis

• When the glucose is entered into the glycolysis pathways, it produces two molecules of ATP and one molecule each of NADPH and FADH.

• The one molecule of NADPH is converted into the three molecules of ATP.

• The one molecule of FADH is converted into two molecules of ATP.

The citric acid cycle

• Citrate (6 carbons) is produced during the cycle by combining acetyl-CoA (2 carbons) and oxaloacetate (4 carbons).

• Citrate is then rearranged to produce isocitrate, which is a more reactive form (6 carbons).

• Isocitrate is converted into oxaloacetate, -ketoglutarate (5 carbons), succinyl-CoA, succinate, fumarate, and malate.

• The net gain of electrons results in three hydrogen-carrying (proton plus electron) compounds, NADH and FADH2, as well as one high-energy GTP that can be used to make ATP.

• The result is a yield of 6 NADH, 2 FADH2, and 2 ATP from 1 glucose molecule and 2 pyruvate molecules.

The Net ATP Produced is

• Two molecules of ATP are produced during glycolysis, as are two molecules of NADH+H+.

• Since 1 NAD+H+ molecule can be converted into 3 ATP molecules through oxidation, 2 NAD+H+ molecules can be converted into 6 ATP molecules. Consequently, in glycolysis:

• Total ATP generated is equal to 2 ATP plus 6 ATP (produced by oxidising NADH and H+), for a total of 8 ATP.

• Pyruvate, a product of glycolysis, enters the mitochondria, where it is subjected to oxidative decarboxylation to produce acetyl CoA. This reaction produces one NADH + H +.

• One molecule of glucose is converted into two molecules of pyruvate, which then go through an oxidative decarboxylation process to create two molecules of NAD+.

• A cyclic pathway called the Krebs cycle is where acetyl CoA enters. Three molecules of NAD+H+, one of FADH2, and one of ATP are produced during one cycle of the Krebs enzyme.

• The Krebs cycle completes two turns as there are two molecules of acetyl CoA produced. As a result, the Krebs cycle produces 6 molecules of NAD+H+, 2 molecules of FADH2, and 2 molecules of ATP over the course of two turns.

• Three ATP molecules are produced during the oxidation of one NADH+H+ molecule.

• Two molecules of ATP result from the oxidation of one FADH2 molecule.

• The Krebs cycle generates a total of 24 ATP: 18 ATP from the oxidation of 6 NADH+H+ and 4 ATP from the oxidation of 2 FADH2.

• Therefore, the Krebs cycle produces 24 ATP molecules.

• The oxidation of FADH and NADH+H+A produces a chain of electrons that is transported by the inner mitochondrial membrane, where reaction 2 occurs.

• As a result, 38 molecules of ATP are created during the complete oxidation of one molecule of glucose.

Conclusion

• Glycolysis is the process by which glucose is broken down into two pyruvate molecules, producing two ATP molecules. The fluid-filled matrix of the mitochondria contains the enzymes for the Krebs cycle. As a result, pyruvate diffuses into the mitochondria, where it is transformed into acetyl CoA and then enters the citric acid cycle.

• 36 ATP molecules are produced during the citric acid cycle. Therefore, two ATP molecules are formed outside of the mitochondria, bringing the total number of ATP molecules produced by aerobic respiration to 38.