Final answer:
Allosteric enzymes are necessary in the regulation or control of metabolic pathways to maintain the balance of reactions and ensure desired reactions are catalyzed. They are controlled by molecules binding to allosteric sites, altering enzyme structure and affinity for substrate. This feedback mechanism allows cells to slow down production when needed.
Step-by-step explanation:
Allosteric enzymes are necessary in the regulation or control of metabolic pathways because they provide an efficient and elegant way for cells to regulate their metabolism. These enzymes can be controlled by the attachment of molecules to allosteric sites on the protein, altering the steric structure of the enzyme and affecting its affinity for its substrate. This feedback mechanism allows the cell to respond to the abundance of specific products and slow down production when needed. Allosteric enzymes play a crucial role in maintaining the balance of metabolic reactions and ensuring that the desired reactions are being catalyzed.