Chapter 18: Problem 83
What is the main function of the citric acid cycle in energy production?
Short Answer
Expert verified
The main function of the citric acid cycle is to produce high-energy molecules NADH and FADH2, which ultimately lead to ATP production.
Step by step solution
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Krebs cycle
The Krebs cycle, also known as the citric acid cycle or TCA cycle, is a central metabolic pathway in the cell. It begins with Acetyl-CoA combining with oxaloacetate to form citrate. This cycle occurs in the mitochondria of eukaryotic cells and is crucial for aerobic respiration. During the process, citrate undergoes a series of enzyme-catalyzed transformations, ultimately regenerating oxaloacetate. This cycle is significant because it helps harvest high-energy molecules like NADH and FADH2, which are essential for ATP production.
By breaking down acetyl groups from Acetyl-CoA, the Krebs cycle generates chemical energy in a form that's easy for the cell to use. This makes it a critical component of cellular respiration.
By breaking down acetyl groups from Acetyl-CoA, the Krebs cycle generates chemical energy in a form that's easy for the cell to use. This makes it a critical component of cellular respiration.
Acetyl-CoA
Acetyl-CoA is a pivotal molecule in metabolism, serving as a fuel for the citric acid cycle. It is derived from the breakdown of carbohydrates, fats, and proteins. The formation of Acetyl-CoA marks the starting point of the Krebs cycle.
The conversion of pyruvate, a product of glycolysis, into Acetyl-CoA is an important step. This process releases one molecule of carbon dioxide and involves the coenzyme A (CoA).
The conversion of pyruvate, a product of glycolysis, into Acetyl-CoA is an important step. This process releases one molecule of carbon dioxide and involves the coenzyme A (CoA).
NADH and FADH2
NADH and FADH2 are coenzymes that act as high-energy electron carriers. These molecules play a significant role in cellular respiration.
During the Krebs cycle, several reactions transfer electrons from metabolic intermediates to NAD+ and FAD, forming NADH and FADH2, respectively. These high-energy electron carriers then transport electrons to the electron transport chain.
Moreover, the reducing power of NADH and FADH2 is essential for the production of ATP, as they donate electrons to the electron transport chain, facilitating oxidative phosphorylation.
During the Krebs cycle, several reactions transfer electrons from metabolic intermediates to NAD+ and FAD, forming NADH and FADH2, respectively. These high-energy electron carriers then transport electrons to the electron transport chain.
Moreover, the reducing power of NADH and FADH2 is essential for the production of ATP, as they donate electrons to the electron transport chain, facilitating oxidative phosphorylation.
electron transport chain
The electron transport chain (ETC) is the final stage of cellular respiration, located in the inner membrane of the mitochondria. Here, electrons carried by NADH and FADH2 are passed through a series of protein complexes.
As electrons move through these complexes, energy is released and used to pump protons (H+) across the mitochondrial membrane. This creates an electrochemical gradient, also known as the proton motive force.
Finally, protons flow back into the mitochondrial matrix through ATP synthase, driving the synthesis of ATP from ADP and inorganic phosphate.
As electrons move through these complexes, energy is released and used to pump protons (H+) across the mitochondrial membrane. This creates an electrochemical gradient, also known as the proton motive force.
Finally, protons flow back into the mitochondrial matrix through ATP synthase, driving the synthesis of ATP from ADP and inorganic phosphate.
ATP production
ATP production is the ultimate goal of cellular respiration. ATP, or adenosine triphosphate, is known as the energy currency of the cell.
The energy stored in NADH and FADH2, produced during the Krebs cycle, is used in the electron transport chain to generate ATP through oxidative phosphorylation. Each NADH can produce about 3 ATP molecules, while each FADH2 can produce about 2 ATP molecules.
In total, the oxidation of one molecule of Acetyl-CoA in the Krebs cycle results in the generation of about 10 ATP molecules, considering the contributions of NADH, FADH2, and direct GTP (or ATP) formation.
The energy stored in NADH and FADH2, produced during the Krebs cycle, is used in the electron transport chain to generate ATP through oxidative phosphorylation. Each NADH can produce about 3 ATP molecules, while each FADH2 can produce about 2 ATP molecules.
In total, the oxidation of one molecule of Acetyl-CoA in the Krebs cycle results in the generation of about 10 ATP molecules, considering the contributions of NADH, FADH2, and direct GTP (or ATP) formation.
