Question

Which of the following is not true of enzymes?

a. Enzyme catalysis is dependent on the pH and temperature of the reaction environment.
b. Enzyme catalysis is dependent on the three-dimensional structure or conformation of the enzyme.
c. Enzymes provide activation energy for the reaction they catalyze.
d. Enzymes are composed primarily of protein, but they may bind nonprotein cofactors.
e. Enzyme activity can be inhibited if the enzyme's allosteric site is bound with a noncompetitive inhibitor

Answer 1

The statement that enzymes provide activation energy is incorrect, as they lower the activation energy of reactions instead. Enzymes catalyze reactions under optimal pH and temperature conditions, and can be inhibited by allosteric interactions.

Step-by-step explanation:

The student asks to determine which statement is not true about enzymes. The correct statement that is not true is: c. Enzymes provide activation energy for the reaction they catalyze. This is because enzymes actually lower the activation energy required for a reaction to take place, rather than providing it. The role of enzymes is to accelerate chemical reactions within the body by creating a specific environment at their active site, where substrate molecules can bind and undergo chemical transformations more easily. Enzymes are also composed of proteins and can be regulated by various factors such as pH, temperature, and the presence of inhibitors.

Factors such as pH and temperature are crucial because they can affect the enzyme's structure, and therefore its function, due to the sensitivity of the amino acid residues at the active site. Enzymes function best within specific environmental conditions, outside of which they may denature. It is also true that enzyme's activity can be inhibited by molecules binding to allosteric sites, which is a form of non-competitive inhibition.