Final answer:
The saturation point of an enzyme is when all active sites are bound to substrate molecules, meaning the enzyme is fully occupied, and adding more substrate won't increase the rate of the reaction.
Step-by-step explanation:
The point at which an enzyme is said to be at its saturation point is when all active sites have bound substrate molecules. This concept is crucial in understanding enzyme kinetics. Enzymes are proteins that facilitate biochemical reactions by providing specific active sites that can only bind to one particular substrate molecule forming an enzyme-substrate complex. This interaction is described by two models: the lock-and-key hypothesis and the induced fit hypothesis. In both models, once the substrate is bound, the reaction occurs, leading to product formation, and the enzyme is free to catalyze another reaction. However, when the concentration of the substrate is very high, every active site of the available enzymes may be occupied, resulting in the saturation of the enzyme. At this saturation point, the addition of more substrate will not increase the rate of reaction because no more active sites are available for binding - the enzyme molecules are saturated with substrate.