Multiple Choice
In human saliva, which enzyme initiates the digestion of starch (amylose) by hydrolyzing glycosidic bonds?
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6. Enzymes and Enzyme Kinetics
Enzymes
Multiple Choice
In the context of enzymes, how does an enzyme affect a chemical reaction?
A
It increases the activation energy (), slowing the reaction while making the reaction more favorable.
B
It changes the equilibrium constant () by stabilizing products more than reactants.
C
It is consumed during the reaction, so it must be replenished to maintain the reaction rate.
D
It lowers the activation energy (), increasing the reaction rate without changing the overall of the reaction.
Verified step by step guidance1
Understand that enzymes are biological catalysts that speed up chemical reactions by lowering the activation energy, denoted as \(E_a\), which is the energy barrier that must be overcome for the reaction to proceed.
Recognize that lowering the activation energy does not affect the equilibrium constant \(K\), which is defined as \(K \equiv \frac{[p]}{[r]}\), where \([p]\) and \([r]\) are the concentrations of products and reactants respectively. The equilibrium position depends on the overall free energy change \(\Delta G\), not on the activation energy.
Note that enzymes are not consumed in the reaction; they participate transiently and are regenerated at the end of the reaction cycle, so they do not need to be replenished continuously to maintain the reaction rate.
Recall that the overall free energy change \(\Delta G\) of the reaction remains unchanged by the presence of the enzyme, meaning the reaction's thermodynamic favorability is not altered, only the rate at which equilibrium is reached is increased.
Summarize that the key role of an enzyme is to lower \(E_a\), thereby increasing the reaction rate without changing \(\Delta G\) or the equilibrium constant \(K\).
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