Metabolic pathways include the catabolic and anabolic reactions in the body needed to perform the necessary body functions such as the formation of molecules, breakdown of molecules and release of energy. These are regulated to maintain the energy demands and demands of other molecules in the body.

The regulation of the metabolic pathways takes place in rate-limiting steps of the reactions by the enzymes. In the case of irreversible reactions, the regulation is needed to make sure that the reaction proceeds in the correct direction. When the number of products increase, the enzymes are inhibited by negative feedback. This regulates the reaction. Similarly, when the amount of reactants increases, the enzymes are stimulated or activated.

The dynamic steady-state is maintained to perform the functions by the cells properly.  This state is present in all living cells. For example, the sodium ions are pumped out of the cell. The sodium still enters the cell when its concentration reduces, This is again pumped out of the cell to maintain the balance. When the cells are not in a dynamic steady-state, the sodium ions are not pumped out and also any amount of sodium ions can enter the cell as there is no regulation. Similarly, the amount of glucose is maintained in the blood during the dynamic steady-state. When the blood glucose level rises, the body sends extra glucose to various sites to maintain the sugar level. When the blood glucose level falls, extra glucose is brought back from these sites to the blood. Thus, maintenance of a dynamic state is necessary for the proper function of the body and this is done by regulation of metabolic pathways.

Practice Questions

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Regulating electron carrier molecules

 MCAT Official Prep (AAMC)

Key Points

• The regulation of metabolic pathways i.e. catabolic and anabolic reactions are necessary to maintain the number of molecules or metabolites and energy in the body cells.

• When the number of products increases, the enzymes are inhibited, thus the metabolic pathway is inhibited too.

• When the number of products decreases, the enzymes are activated, thus the metabolic pathway is activated too.

• A dynamic steady state is an equilibrium state that is in a dynamic state. It means that equilibrium or balance is maintained continuously based on the need of the body.

• To maintain the body cells in a dynamic steady state, regulation of metabolic pathways is necessary.

Key Terms

catabolic: breakdown of molecules into smaller molecules with the release of energy

anabolic: Formation of larger molecules from smaller molecules with the utilization of energy