The graph provided shows how the
addition of an enzyme affects a biochemical reaction. What key aspect of this reaction
has changed with the addition of an enzyme? (A) There have been no obvious
changes. (B) The activation energy has been
lowered. (C) The free energy of the reaction
has increased. (D) The volume of products formed
has decreased. Or (E) the time taken for the
reaction to become complete has increased.
Let’s start by reviewing some
terms. An enzyme is a protein that
catalyzes chemical reactions or helps those chemical reactions happen more
effectively by binding the reactants of the reaction or the substrates and orienting
them properly or otherwise preparing them for the chemical reaction to more easily
occur. Through this type of action, we
generally say that enzymes make chemical reactions more efficient by lowering the
energy required for the reaction to occur.
In the graph that we’re provided
with, we can see that we have reaction progress along the horizontal axis and free
energy or the energy used or required for the reaction along the vertical axis. And we also see two lines, a red
line and a green line, which correspond to the reaction happening with the enzyme or
without the enzyme. We can see that both lines start
and end in the same places and that they also have the same general shape, including
this peak of energy that’s required towards the beginning of the reaction.
However, we can also see that the
red line, which indicates the reaction without the enzyme, has a much higher peak
than the green line, which indicates the reaction happening with the enzyme. And we can see that both of these
peaks are labeled with this symbol 𝐸 sub a, which stands for energy of activation
or activation energy. The activation energy is the energy
required to get a reaction started.
So because the red line’s peak is
higher, we can see that 𝐸 sub a, or activation energy, is higher for the reaction
without the enzyme than the reaction with the enzyme. And this is the only major
difference we see between the two lines in this graph. So what key aspect of this reaction
has changed with the addition of an enzyme? In the graph, we can see that with
the addition of an enzyme, the activation energy has been lowered.