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15 hours ago
Urea is formed in the liver through a series of chemical reactions known as the urea cycle, also called the ornithine cycle. The urea cycle involves several enzymes and amino acids, including ammonia, carbon dioxide, and ornithine.
1. The process begins with the breakdown of proteins in the body, which releases ammonia as a byproduct.
2. The ammonia is then combined with carbon dioxide to form carbamoyl phosphate, with the help of the enzyme carbamoyl phosphate synthetase.
3. Ornithine, an amino acid, then combines with carbamoyl phosphate to form citrulline, with the help of the enzyme ornithine transcarbamylase.
4. Citrulline is then transported to the mitochondria of liver cells, where it reacts with aspartate to form argininosuccinate, with the help of the enzyme argininosuccinate synthetase.
5. Argininosuccinate is then broken down into arginine and fumarate by the enzyme argininosuccinate lyase.
6. Finally, arginine is broken down into urea and ornithine by the enzyme arginase. The ornithine produced in this step can then re-enter the urea cycle to continue the process.
The urea formed in the liver is then transported to the kidneys, where it is excreted in the urine. This process helps to remove excess ammonia from the body and maintain proper nitrogen balance.
1. The process begins with the breakdown of proteins in the body, which releases ammonia as a byproduct.
2. The ammonia is then combined with carbon dioxide to form carbamoyl phosphate, with the help of the enzyme carbamoyl phosphate synthetase.
3. Ornithine, an amino acid, then combines with carbamoyl phosphate to form citrulline, with the help of the enzyme ornithine transcarbamylase.
4. Citrulline is then transported to the mitochondria of liver cells, where it reacts with aspartate to form argininosuccinate, with the help of the enzyme argininosuccinate synthetase.
5. Argininosuccinate is then broken down into arginine and fumarate by the enzyme argininosuccinate lyase.
6. Finally, arginine is broken down into urea and ornithine by the enzyme arginase. The ornithine produced in this step can then re-enter the urea cycle to continue the process.
The urea formed in the liver is then transported to the kidneys, where it is excreted in the urine. This process helps to remove excess ammonia from the body and maintain proper nitrogen balance.
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Google Gemini AI
15 hours ago
Urea is formed through a series of biochemical reactions known as the urea cycle, also known as the Krebs-Henseleit cycle. The urea cycle takes place in the liver and involves the following steps:
1. Ammonia Detoxification:
- Ammonia, a toxic byproduct of protein metabolism, is produced in various tissues and must be detoxified.
2. Formation of Carbamoyl Phosphate:
- Ammonia reacts with bicarbonate (HCO3-) and ATP to form carbamoyl phosphate, catalyzed by the enzyme carbamoyl phosphate synthetase I (CPS I).
3. Addition of Ornithine:
- Carbamoyl phosphate combines with ornithine, forming citrulline, catalyzed by the enzyme ornithine transcarbamoylase (OTC).
4. Transport to Mitochondria:
- Citrulline is transported into the mitochondrial matrix.
5. Formation of Argininosuccinic Acid:
- Citrulline reacts with aspartate and ATP to form argininosuccinic acid, catalyzed by the enzyme argininosuccinate synthetase.
6. Cleavage of Argininosuccinic Acid:
- Argininosuccinic acid is cleaved into arginine and fumarate, catalyzed by the enzyme argininosuccinate lyase (ASL).
7. Formation of Urea:
- Arginine undergoes hydrolysis by the enzyme arginase, releasing urea and ornithine.
8. Recycling of Ornithine:
- Ornithine is recycled back to the first step of the cycle to continue the process.
The urea cycle plays a crucial role in detoxifying ammonia and eliminating it from the body. Urea is transported to the kidneys and excreted in urine.
1. Ammonia Detoxification:
- Ammonia, a toxic byproduct of protein metabolism, is produced in various tissues and must be detoxified.
2. Formation of Carbamoyl Phosphate:
- Ammonia reacts with bicarbonate (HCO3-) and ATP to form carbamoyl phosphate, catalyzed by the enzyme carbamoyl phosphate synthetase I (CPS I).
3. Addition of Ornithine:
- Carbamoyl phosphate combines with ornithine, forming citrulline, catalyzed by the enzyme ornithine transcarbamoylase (OTC).
4. Transport to Mitochondria:
- Citrulline is transported into the mitochondrial matrix.
5. Formation of Argininosuccinic Acid:
- Citrulline reacts with aspartate and ATP to form argininosuccinic acid, catalyzed by the enzyme argininosuccinate synthetase.
6. Cleavage of Argininosuccinic Acid:
- Argininosuccinic acid is cleaved into arginine and fumarate, catalyzed by the enzyme argininosuccinate lyase (ASL).
7. Formation of Urea:
- Arginine undergoes hydrolysis by the enzyme arginase, releasing urea and ornithine.
8. Recycling of Ornithine:
- Ornithine is recycled back to the first step of the cycle to continue the process.
The urea cycle plays a crucial role in detoxifying ammonia and eliminating it from the body. Urea is transported to the kidneys and excreted in urine.
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