Which of the Following is True of Enzymes

Question

Which of the following is true of enzymes?
A) Nonprotein cofactors alter the substrate specificity of enzymes.
B) Enzyme function is increased if the 3-D structure or conformation of an enzyme is altered.
C) Enzyme function is independent of physical and chemical environmental factors such as pH and temperature.
D) Enzymes increase the rate of chemical reaction by lowering activation energy barriers.
E) Enzymes increase the rate of chemical reaction by providing activation energy to the substrate.

Accepted Answer

Enzymes lower the activation energy barriers, thereby increasing the rate of chemical reactions. This is done by providing an alternative reaction pathway with a lower activation energy. Enzyme function is also influenced by physical and chemical environmental factors such as pH and temperature. Enzymes are usually proteins with specific 3-D structures, and any alteration to this structure can affect their function. Nonprotein cofactors can also bind to enzymes and alter their substrate specificity. Therefore, option D is the correct choice.