So in this diagram, these red dots are basically the NAD plus molecules, and these blue figures are the lactate. So we take this solution and we add the enzyme sample into our solution. And if one of the enzymes in that sample is lactate dehydrogenase, then these blue figures will be converted into these purple Pyruvate molecules. In the process, the red NAD plus molecules will be converted to the green NADH molecules. And as this process is taking place, we're measuring how much light is being absorbed. And if that is increasing, then we know that our enzyme is present because only this enzyme can catalyze this reaction.