Final answer:
Cells can vary enzyme amount through gene regulation and post-translational modification.
Step-by-step explanation:
Cells can vary the amount of enzyme present through both gene regulation and post-translational modification.
Gene regulation involves turning genes on and off, typically by controlling transcription. This process starts with extracellular chemical signaling and can be influenced by factors such as hormones or nutrient levels, allowing the cell to respond to its environment.
Post-translational modification refers to modifying the protein after it is made, affecting its activity. This can occur through enzyme inhibition, adding functional groups, or regulating protein location within the cell.