Question Video: Determining the Optimum pH of an Enzyme Using a Given Graph That Shows How This Enzyme's Activity Is Affected by Changes in pH Biology

The graph shows how the rate of an enzyme-controlled reaction changes with the pH. What is the optimum pH of this enzyme?

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Video Transcript

The graph provided shows how the rate of an enzyme-controlled reaction changes with the pH. What is the optimum pH of this enzyme?

Key knowledge required to answer this question correctly is an understanding of factors that affect enzyme action. And a good place to start is gonna be a review of how enzymes control chemical reactions. In chemical reactions, a reactant or reactants are converted into a product or products. And if the chemical reaction is controlled by an enzyme, then we call the reactant a substrate.

An enzyme’s active site has a complimentary shape to the substrate, meaning that they fit together sort of like a lock and key. The binding of the substrate to the enzyme reduces the amount of energy required to start the reaction. And reactions that occur more easily can also occur more frequently. So, enzymes increase the rate of reactions that they control. And rate of reaction is an important term in this question.

The function of an enzyme is to speed up or catalyze chemical reactions, and that’s another way of saying increasing the rate of reaction. And we wanna know what the optimum or highest rate of reaction is over a range of pH values for a certain enzyme. Well, this point here represents the highest or optimum rate of reaction. So, we just need to find its corresponding pH value, which we can see is seven.

And if you’re not familiar with the pH scale, here’s a quick review. Acids are on the lower end of the pH scale. Seven is neutral and above seven is a basic or alkaline pH. Therefore, the answer to the question, what is the optimum pH of this enzyme? is pH seven.

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