Question

Examine your graph and look for patterns in the data. (a) Does the concentration of Pi increase evenly through the course of the experiment? To answer this question, describe the pattern you see in the graph. (b) What part of the graph shows the highest rate of enzyme activity? Consider that the rate of enzyme activity is related to the slope of the line, Δy/ Δx (the “rise” over the “run”), in µmol/(mL·min), with the steepest slope indicating the highest rate of enzyme activity. Calculate the rate of enzyme activity (slope) where the graph is steepest. (c) Can you think of a biological explanation for the pattern you see?

Short answer

1. No, the concentration of Pi (phosphate ion) does not increase evenly throughout the experiment.
2. The enzyme activity is maximum between 5 to 20 mins. The slope of the graph is 17 µmol/mL·min.
3. Initially, enzymes activity is highest when they are saturated with the substrate. However, the activity gradually slows down when the substrate is used up in the experiment.

Step-by-step solution

Explanation for (a)

From the graph, it is observed that the concentration of Pi increases slowly initially. It then rises rapidly and then gradually becomes constant. This exhibits that the concentration of Pi does not increase evenly with the course of the experiment.

Explanation for (b)

The enzyme activity is less at the beginning; however, it increases and reaches a maximum between 5 to 20 mins.

The slop of the graph:

$$\begin{gathered} \text{Slope =}\frac{{\text{y}}_{\text{2}}{\text{-y}}_{\text{1}}}{{\text{x}}_{\text{2}}{\text{-x}}_{\text{1}}} \\ =\frac{270-10}{20-15} \\ =17.33 \end{gathered}$$

Thus, the rate of enzyme activity where the graph is steepest is 17 µmol/mL·min.

Explanation for (c)       

The slope of the graph is steepest when the enzyme activity is highest because the enzymes are saturated with substrate. As a result, a high concentration of the product (Pi) is released.

However, the slope gradually reaches zero; when the enzyme activity slows down, substrates are no longer available for the enzymes to bind. Thus, no products are released, and the concentration of Pi becomes constant.