Energy Yield in ATP Molecules

Oct 13, 2025 by leolavanderia.com.br 72 views

Introduction

The process of cellular respiration is a complex series of reactions that occur within the cells of living organisms. It involves the breakdown of glucose and other organic molecules to produce energy in the form of ATP (adenosine triphosphate). The citric acid cycle (CAC) and the electron transport chain (ETC) are two crucial components of cellular respiration that work together to generate energy. In this article, we will explore the energy yield in ATP molecules of one turn of CAC combined with the ETC.

The Citric Acid Cycle (CAC)

The citric acid cycle, also known as the Krebs cycle or tricarboxylic acid (TCA) cycle, is a series of chemical reactions that occur within the mitochondria of cells. It is a key process by which cells generate energy from the breakdown of glucose and other organic molecules. The CAC takes place in the mitochondrial matrix and involves the conversion of acetyl-CoA into citrate, which is then converted into oxaloacetate. This process results in the production of NADH and FADH2, which are electron carriers that play a crucial role in the electron transport chain.

The Electron Transport Chain (ETC)

The electron transport chain is a series of protein complexes located in the mitochondrial inner membrane. It is responsible for generating energy from the electrons passed through the electron carriers NADH and FADH2. The ETC consists of five protein complexes (I, II, III, IV, and V) and two electron carriers (ubiquinone and cytochrome c). As electrons flow through the ETC, they lose energy, which is used to pump protons across the mitochondrial inner membrane. This creates a proton gradient, which is used to generate ATP through the process of chemiosmosis.

Energy Yield in ATP Molecules

The energy yield in ATP molecules of one turn of CAC combined with the ETC is a complex process that involves the conversion of chemical energy into electrical energy and then into mechanical energy. The CAC produces 2 NADH and 1 FADH2 molecules per turn, which are then passed through the ETC. The ETC generates a proton gradient, which is used to produce ATP through the process of chemiosmosis. The energy yield in ATP molecules can be calculated as follows:

2 NADH molecules produce 2.5 ATP molecules each
1 FADH2 molecule produces 1.5 ATP molecules

Therefore, the total energy yield in ATP molecules of one turn of CAC combined with the ETC is:

2.5 ATP (from NADH) + 1.5 ATP (from FADH2) = 4 ATP

Chemiosmosis

Chemiosmosis is the process by which the energy from the proton gradient is used to generate ATP. It involves the movement of protons across the mitochondrial inner membrane, which drives the production of ATP. The process of chemiosmosis can be summarized as follows:

Protons are pumped across the mitochondrial inner membrane, creating a proton gradient.
The proton gradient drives the production of ATP through the enzyme ATP synthase.
ATP synthase uses the energy from the proton gradient to drive the production of ATP.

Conclusion

In conclusion, the energy yield in ATP molecules of one turn of CAC combined with the ETC is 4 ATP molecules. This process involves the conversion of chemical energy into electrical energy and then into mechanical energy. The CAC produces 2 NADH and 1 FADH2 molecules per turn, which are then passed through the ETC. The ETC generates a proton gradient, which is used to produce ATP through the process of chemiosmosis. This process is a crucial component of cellular respiration and is essential for the generation of energy in living organisms.

References

Lehninger, A. L., Nelson, D. L., & Cox, M. M. (2008). Principles of biochemistry. 4th ed. New York: W.H. Freeman and Company.
Stryer, L. (1995). Biochemistry. 4th ed. New York: W.H. Freeman and Company.
Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K., & Walter, P. (2002). Molecular biology of the cell. 5th ed. New York: Garland Science.

FAQs

Q: What is the energy yield in ATP molecules of one turn of CAC combined with the ETC? A: The energy yield in ATP molecules of one turn of CAC combined with the ETC is 4 ATP molecules.
Q: What is the role of the citric acid cycle in cellular respiration? A: The citric acid cycle is a series of chemical reactions that occur within the mitochondria of cells. It is a key process by which cells generate energy from the breakdown of glucose and other organic molecules.
Q: What is the role of the electron transport chain in cellular respiration? A: The electron transport chain is a series of protein complexes located in the mitochondrial inner membrane. It is responsible for generating energy from the electrons passed through the electron carriers NADH and FADH2.
Q&A: Energy Yield in ATP Molecules of One Turn of CAC Combined with the ETC ====================================================================

Q: What is the energy yield in ATP molecules of one turn of CAC combined with the ETC?

A: The energy yield in ATP molecules of one turn of CAC combined with the ETC is 4 ATP molecules. This is calculated by adding the energy yield from NADH (2.5 ATP) and FADH2 (1.5 ATP) molecules.

Q: What is the role of the citric acid cycle in cellular respiration?

A: The citric acid cycle is a series of chemical reactions that occur within the mitochondria of cells. It is a key process by which cells generate energy from the breakdown of glucose and other organic molecules. The citric acid cycle produces 2 NADH and 1 FADH2 molecules per turn, which are then passed through the electron transport chain.

Q: What is the role of the electron transport chain in cellular respiration?

A: The electron transport chain is a series of protein complexes located in the mitochondrial inner membrane. It is responsible for generating energy from the electrons passed through the electron carriers NADH and FADH2. The electron transport chain generates a proton gradient, which is used to produce ATP through the process of chemiosmosis.

Q: What is chemiosmosis?

A: Chemiosmosis is the process by which the energy from the proton gradient is used to generate ATP. It involves the movement of protons across the mitochondrial inner membrane, which drives the production of ATP.

Q: How does the citric acid cycle produce NADH and FADH2 molecules?

A: The citric acid cycle produces NADH and FADH2 molecules through a series of chemical reactions. The citric acid cycle takes place in the mitochondrial matrix and involves the conversion of acetyl-CoA into citrate, which is then converted into oxaloacetate. This process results in the production of NADH and FADH2 molecules.

Q: What is the difference between NADH and FADH2 molecules?

A: NADH and FADH2 molecules are both electron carriers that play a crucial role in the electron transport chain. However, they differ in their energy yield. NADH molecules produce 2.5 ATP molecules, while FADH2 molecules produce 1.5 ATP molecules.

Q: How does the electron transport chain generate a proton gradient?

A: The electron transport chain generates a proton gradient through a series of protein complexes located in the mitochondrial inner membrane. As electrons flow through the electron transport chain, they lose energy, which is used to pump protons across the mitochondrial inner membrane. This creates a proton gradient, which is used to produce ATP through the process of chemiosmosis.

Q: What is the significance of the proton gradient in cellular respiration?

A: The proton gradient is a crucial component of cellular respiration. It is used to generate ATP through the process of chemiosmosis. The proton gradient is created by the electron transport chain and is used to drive the production of ATP.

Q: How does the energy yield in ATP molecules of one turn of CAC combined with the ETC compare to other energy-producing processes?

A: The energy yield in ATP molecules of one turn of CAC combined with the ETC is 4 ATP molecules. This is a relatively high energy yield compared to other energy-producing processes. For example, the energy yield from glycolysis is 2 ATP molecules, while the energy yield from the electron transport chain is 32-34 ATP molecules.

Q: What are some of the key factors that affect the energy yield in ATP molecules of one turn of CAC combined with the ETC?

A: Some of the key factors that affect the energy yield in ATP molecules of one turn of CAC combined with the ETC include the concentration of NADH and FADH2 molecules, the efficiency of the electron transport chain, and the presence of inhibitors or uncouplers.

Q: How does the energy yield in ATP molecules of one turn of CAC combined with the ETC relate to cellular respiration?

A: The energy yield in ATP molecules of one turn of CAC combined with the ETC is a crucial component of cellular respiration. It is used to generate energy from the breakdown of glucose and other organic molecules. The energy yield in ATP molecules of one turn of CAC combined with the ETC is essential for the survival and function of cells.