Final answer:
Enzymes are regulated through covalent modification, involving the addition or removal of chemical groups, and allosteric control, where allosteric effectors bind to non-active sites, modulating enzyme activity as part of a feedback mechanism.
Step-by-step explanation:
Enzymes can be regulated through various mechanisms, two of which are covalent modification and allosteric control. Covalent modification often involves the cyclic inter-conversion of an enzyme between its modified and unmodified forms. This is regulated by the attachment or removal of specific chemical groups such as phosphates. Allosteric control, on the other hand, is regulated by the binding of allosteric effectors to the allosteric sites on the enzyme, which are distinct from the active site. These molecules can alter the enzyme's activity by causing conformational changes that affect the enzyme's ability to bind to its substrate, thereby increasing or decreasing the reaction rate.
Common allosteric effectors include nucleotides like ATP, ADP, AMP, NAD+, and NADH. The binding of these molecules to the allosteric site sends a signal that modulates the enzyme's activity. This provides a feedback mechanism that adjusts the enzyme's function based on the cell's metabolic needs.