Final answer:
Feedback inhibition alters the activity of the first enzyme of a metabolic pathway rather than one of the latter enzymes because it allows for more efficient regulation. By inhibiting the first enzyme, the cell can quickly and effectively slow down or halt the production of the pathway's end product when it is no longer needed.
Step-by-step explanation:
Feedback inhibition typically alters the activity of the first enzyme of a metabolic pathway rather than one of the latter enzymes because it allows for more efficient regulation of the pathway. The first enzyme is often the rate-limiting step in the pathway, meaning it controls the overall rate of the pathway. By inhibiting the first enzyme, the cell can quickly and effectively slow down or halt the production of the pathway's end product when it is no longer needed.
For example, let's say there is a metabolic pathway that produces substance E. Under normal conditions, another series of reactions would consume E. However, if there is an excess of E in the cell, it might bind to enzyme 1, the first enzyme of the pathway. This binding causes an allosteric change, inhibiting catalysis and slowing down the entire pathway. This allosteric regulation, called feedback inhibition, allows the cell to control the rate of production of substance E based on its abundance in the cell.
Overall, feedback inhibition at the first enzyme of a metabolic pathway is important for efficient regulation and control of the pathway by quickly responding to changes in the abundance of the pathway's end product.