Which option correctly replaces the letters X and Y?
A(n) X will bind to the Y of an enzyme so that the chemical reaction can occur.
X: active site
Y: reactant
X: active site, , Y: reactant
X: substrate
Y: active site
X: substrate, , Y: active site
X: substrate
Y: product
X: substrate, , Y: product
X: product
Y: reactant
X: product, , Y: reactant
To answer this question, we need to understand the concept of enzyme-substrate interactions in chemical reactions.
In an enzyme-substrate interaction, the substrate is the molecule that binds to the active site of the enzyme. The active site is the specific region on the enzyme where the substrate binds and undergoes a chemical reaction to either form a product or be modified in some way.
Looking at the options provided:
Option A: (X: active site, Y: reactant) - This option suggests that the active site binds to the reactant, which is not accurate. The reactant is the starting material that will undergo a reaction, while the active site is the region on the enzyme where the reaction takes place.
Option B: (X: substrate, Y: active site) - This option correctly identifies the substrate as X and the active site as Y. The substrate binds to the active site for the reaction to occur. This choice represents the correct replacement for X and Y.
Option C: (X: substrate, Y: product) - This option incorrectly identifies the product as Y. The product is the result of the reaction, not the region on the enzyme where the reaction occurs. So, this option does not accurately replace X and Y.
Option D: (X: product, Y: reactant) - This option incorrectly identifies the product as X and the reactant as Y. The product is the result of the reaction, not the region on the enzyme where the reaction occurs. So, this option does not accurately replace X and Y.
Therefore, the correct option is B: (X: substrate, Y: active site).