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.
