Krebs / citric acid cycle | Cellular respiration | Biology | Khan Academy
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Glycolysis and the Krebs cycle convert glucose into ATP and other energy carriers, yielding a total of 38 ATPs through cellular respiration, which includes the electron transport chain. Acetyl-CoA plays a crucial role in this process, allowing for the catabolism of carbohydrates, proteins, and fats, showcasing the body's energy production versatility.
Insights
- Glycolysis initiates the breakdown of glucose by converting it into two 3-carbon pyruvate molecules, resulting in a net gain of 2 ATPs and 2 NADHs, and this process occurs in the cytoplasm without the need for oxygen, making it adaptable to both aerobic and anaerobic environments.
- The Krebs cycle, which follows glycolysis, processes acetyl-CoA to produce carbon dioxide, ATP, NADH, and FADH2, ultimately contributing to the electron transport chain, where the combined yield from one glucose molecule can reach a theoretical maximum of 38 ATPs, showcasing the efficiency of cellular respiration in energy production.
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Recent questions
What is cellular respiration?
Cellular respiration is a biochemical process that converts glucose and other organic molecules into energy in the form of adenosine triphosphate (ATP). It involves several stages, including glycolysis, the Krebs cycle, and the electron transport chain. Glycolysis occurs in the cytoplasm and breaks down glucose into pyruvate, yielding a small amount of ATP and NADH. The Krebs cycle, which takes place in the mitochondrial matrix, further processes pyruvate into carbon dioxide while generating more NADH, FADH2, and ATP. Finally, the electron transport chain utilizes the NADH and FADH2 produced to create a significant amount of ATP through oxidative phosphorylation. The entire process is essential for providing energy to cells and can occur under both aerobic and anaerobic conditions.
How do enzymes function in metabolism?
Enzymes play a crucial role in metabolism by acting as biological catalysts that speed up chemical reactions within the body. Each enzyme is specific to a particular reaction or type of reaction, lowering the activation energy required for the reaction to proceed. In the context of cellular respiration, enzymes facilitate each step of the metabolic pathways, such as glycolysis and the Krebs cycle, ensuring that glucose is efficiently converted into ATP. By binding to substrates and stabilizing the transition state, enzymes increase the rate of reactions, allowing cells to meet their energy demands effectively. Without enzymes, metabolic processes would occur too slowly to sustain life.
What is the role of acetyl-CoA?
Acetyl-CoA is a vital metabolic intermediate that plays a key role in cellular respiration. It is produced from the breakdown of carbohydrates, fats, and proteins, making it a central hub for energy production. Once formed, acetyl-CoA enters the Krebs cycle, where it combines with oxaloacetic acid to form citric acid, initiating a series of reactions that lead to the production of ATP, NADH, and FADH2. This versatility allows the body to utilize various fuel sources for energy, highlighting the importance of acetyl-CoA in metabolism. Its ability to link different metabolic pathways underscores its significance in maintaining energy homeostasis in the body.
What is the Krebs cycle?
The Krebs cycle, also known as the citric acid cycle, is a series of enzymatic reactions that occur in the mitochondrial matrix, playing a critical role in cellular respiration. It begins with the combination of acetyl-CoA and oxaloacetic acid to form citric acid, which undergoes a series of transformations. Throughout the cycle, citric acid is oxidized, leading to the release of carbon dioxide and the production of high-energy molecules, including NADH, FADH2, and ATP. For each turn of the cycle, significant amounts of energy are harvested, which are essential for the subsequent electron transport chain. The Krebs cycle is fundamental for energy production and is a key component of aerobic metabolism.
How is ATP produced in cells?
ATP, or adenosine triphosphate, is produced in cells through a series of metabolic processes, primarily during cellular respiration. The process begins with glycolysis, where glucose is broken down into pyruvate, yielding a small amount of ATP. Following glycolysis, the Krebs cycle further processes pyruvate, generating additional ATP along with NADH and FADH2. The majority of ATP is produced during the electron transport chain, where the high-energy electrons from NADH and FADH2 are transferred through a series of proteins, ultimately leading to the synthesis of ATP via oxidative phosphorylation. This efficient production of ATP is crucial for powering various cellular functions and maintaining overall energy balance in the body.