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What is the Metabolic Pathway?

L. Roux
L. Roux

The metabolic pathway is a series of chemical reactions that occur within a cell. Within each of these pathways, one chemical is transformed into another chemical through a series of steps. These reactions are catalyzed by enzymes and will often require vitamins and minerals in order to function properly.

One of the first studies of metabolic pathways was done by a British physician named Archibald Garrod in 1909. It was discovered that the most important metabolic pathways for humans are glycolysis—the first pathway discovered—, Krebs cycle, oxidative phosphorylation and gluconeogenesis. The collection of all the pathways within the human body is called the metabolic network, and this determines the physiological and biochemical properties of a cell.

Woman with hand on her hip
Woman with hand on her hip

Enzymes are considered to be very important to they body's metabolic pathway. They act as catalysts in various chemical reactions that occur in the body's cells. Enzymes convert substrates into various molecules or products. Since enzymes are selective and will only catalyze a few chosen reactions, the set of enzymes made in a cell determines which metabolic pathways occur in that cell. Enzyme activity can be affected by other molecules; inhibitors will decrease their activity, while activators will increase it.

The body's metabolism is divided into two phases: anabolism and catabolism. Anabolism uses energy to construct the components of a cell, such as proteins, whereas catabolism involves the breakdown of organic matter. The result of this metabolic process may either be stored by the cells or used to initiate another metabolic pathway. The metabolic pathway and its activities will depend on other factors as well, including the temperature and the chemical environment, also known as the pH level.

The metabolic pathway is usually believed to travel in one direction, and it is composed of a series of chemical reactions that are connected to each other. These processes allow living organisms to grow and adapt to their environment. The metabolic process will also determine which substances are nutritious and which ones are poisonous. The speed of metabolism in an organism is also known as the metabolic rate.

Other metabolic pathways that occur in most living organisms include fatty acid oxidation and the urea cycle. In humans, the urea cycle takes place primarily in the liver, and it involves the production of urea from ammonia. Fatty acid oxidation is the process in which fat molecules are broken down into free fatty acids and monoglycerides.

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Discussion Comments


That is a common misconception, especially as ammonia is used in cleaning products and other items such as fertilizer; however, ammonia is actually a naturally occurring substance and as you have started to figure out - it is something that our body actually needs.

Ammonia is actually present in our bodies at all times and we need ammonia to maintain our pH. The amount of ammonia needed and the amount of ammonia in a person's body varies based on their diet and other factors.

I do not know enough just yet to know how much is too much or if you can even have too much ammonia in your body's systems.


The metabolic pathway is said to involve creating urea from ammonia.

I always thought ammonia was a toxic substance, how does it get into our bodies and not harm us?

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