Substrate

Definition

A substrate is the substance upon which an enzyme acts, or the reactant that is converted into product(s) by a chemical reaction. It is the starting material in a biochemical or chemical process.

5 Must Know Facts For Your Next Test

1. The concentration of the substrate is a key factor that affects the rate of an enzyme-catalyzed reaction.
2. Increasing the substrate concentration typically increases the reaction rate up to a maximum, after which the rate levels off.
3. Catalysts work by providing an alternative pathway for the reaction, lowering the activation energy required and increasing the reaction rate.
4. The structure of the substrate must be complementary to the active site of the enzyme for the reaction to occur efficiently.
5. In heterogeneous catalysis, the substrate is typically a gas or liquid that interacts with the surface of a solid catalyst.

Review Questions

• Explain how the concentration of the substrate affects the rate of an enzyme-catalyzed reaction.
  • The concentration of the substrate is a key factor that affects the rate of an enzyme-catalyzed reaction. As the substrate concentration increases, more substrate molecules are available to bind to the active sites of the enzymes, leading to a higher frequency of successful collisions and a faster rate of product formation. However, the rate of the reaction will eventually reach a maximum as the enzyme active sites become saturated with substrate, and further increases in substrate concentration will not significantly increase the reaction rate.
• Describe the role of the substrate in the context of catalysis.
  • In the context of catalysis, the substrate is the reactant that undergoes a chemical transformation facilitated by the presence of a catalyst. The catalyst works by providing an alternative pathway for the reaction, lowering the activation energy required and increasing the reaction rate. The structure of the substrate must be complementary to the active site of the catalyst for the reaction to occur efficiently. In heterogeneous catalysis, the substrate is typically a gas or liquid that interacts with the surface of a solid catalyst, allowing the reaction to proceed at a faster rate compared to the uncatalyzed reaction.
• Analyze the relationship between the substrate concentration and the reaction rate in the context of 12.2 Factors Affecting Reaction Rates and 12.7 Catalysis.
  • The concentration of the substrate is a key factor that affects the rate of a chemical reaction, as described in the topic 12.2 Factors Affecting Reaction Rates. Increasing the substrate concentration typically increases the reaction rate up to a maximum, after which the rate levels off. This is because as the substrate concentration increases, more substrate molecules are available to bind to the active sites of enzymes or catalysts, leading to a higher frequency of successful collisions and a faster rate of product formation. However, the rate of the reaction will eventually reach a maximum as the active sites become saturated with substrate. In the context of 12.7 Catalysis, the catalyst works by providing an alternative pathway for the reaction, lowering the activation energy required and increasing the reaction rate. The structure of the substrate must be complementary to the active site of the catalyst for the reaction to occur efficiently, further emphasizing the importance of the substrate in the catalytic process.

Related terms

Enzyme:

A protein that catalyzes a specific chemical reaction, increasing the rate of the reaction without being consumed in the process.

Catalyst:

A substance that increases the rate of a chemical reaction without being consumed or altered itself.

Reaction Rate:

The speed at which the reactants are converted into products in a chemical reaction.