Video Transcript
Which of the following statements
correctly links enzymes, substrates, and active sites? (A) The substrate has an active
site that has a complementary shape to a range of enzymes. (B) The enzyme has an active site
that has a complementary shape to a specific substrate. (C) The enzyme has an active site
that has an identical shape to a range of substrates. (D) The substrate has an active
site that has an identical shape to a specific enzyme. (E) The enzyme’s active site is
constantly changing to have a complementary shape to a range of substrates.
The question asks us to find a
statement that correctly links enzymes, substrates, and active sites. In order to answer this question,
let’s go over the definition of each of these terms.
An enzyme is often referred to as a
biological catalyst because it speeds up the rate of reactions by lowering the
activation energy required for the reaction to take place. These molecules are never used up
in the reaction. Instead, they are recycled. Every enzyme has an active site,
which is a region on the surface of the enzyme where its specific substrate will
bind to. A substrate is a single molecule,
or a combination of molecules, that has a complementary shape to the enzyme’s active
site. This allows the enzyme and
substrate to bind together and form the enzyme–substrate complex. Once the enzyme and substrate bind
via the enzyme’s active site, thereby forming an enzyme–substrate complex, the
substrate is converted into its products.
Now that we have defined enzymes,
substrates, and active sites, we can take another look at our answer choices. We need to find an answer that
attributes the active site to the enzyme, since it is the enzyme that contains the
active site and not the substrate. We also need to find an answer that
highlights the complementarity between the enzyme’s active site and its specific
substrate.
Therefore, the correct answer to
our question is answer choice (B). The enzyme has an active site that
has a complementary shape to a specific substrate.
