Consider the two-step metabolic pathway: A - (enzyme 1) - >B - (enzyme 2) - >C How would inactivating enzyme 1 affect the concentrations of molecules A, B, and C relative to what they would be if the pathway were fully functional?

A increases, B and C decrease

Explanation:

Enzyme 1 uses A as substrate to produce B. In turn, B is the precursor of C.

If enzyme 1 is inactivated, A cannot be converted into B, so A will accumulate (its concentration will increase) while B's concentration decreases. Because B's concentration decreases, there won't be enough of it to produce C, so the concentration of C will also be lower than in a fully functional pathway.