Enzymes

Definition

Enzymes are biological catalysts that speed up chemical reactions in living organisms by lowering the activation energy required for those reactions to occur. They are essential for various metabolic processes, ensuring that reactions happen at a rate suitable for life. Enzymes can be specific to substrates and function optimally under particular conditions, like temperature and pH.

5 Must Know Facts For Your Next Test

1. Enzymes are usually proteins, although some RNA molecules can also function as enzymes (these are called ribozymes).
2. Each enzyme is specific to a particular reaction or type of reaction, determined by its unique structure.
3. Enzymes can be influenced by environmental factors such as temperature, pH, and substrate concentration, which can affect their activity.
4. The enzyme-substrate complex forms when the substrate binds to the active site of the enzyme, facilitating the conversion of substrate into product.
5. Enzymes can be reused multiple times in chemical reactions because they are not consumed in the reaction process.

Review Questions

• How do enzymes affect the activation energy of a chemical reaction?
  • Enzymes lower the activation energy required for a chemical reaction to occur. By providing an alternative reaction pathway, enzymes allow reactions to proceed more quickly and efficiently. This means that even reactions with high activation energies can occur at body temperature, which is vital for sustaining life processes.
• Discuss how environmental conditions like pH and temperature can influence enzyme activity.
  • Environmental conditions such as pH and temperature significantly impact enzyme activity. Each enzyme has an optimal pH and temperature range where it functions best. Deviations from these optimal conditions can lead to denaturation, where the enzyme loses its shape and functionality, or decreased activity due to altered kinetic properties.
• Evaluate the role of enzymes in biochemical pathways and how they contribute to metabolic regulation.
  • Enzymes play a crucial role in biochemical pathways by regulating the speed and efficiency of metabolic processes. They act as gatekeepers, controlling the flow of substrates through pathways by facilitating specific reactions. The regulation of enzyme activity is vital for maintaining homeostasis, allowing organisms to adapt their metabolism according to environmental changes and energy needs. In this way, enzymes ensure that metabolic pathways function smoothly and efficiently.

Related terms

Substrate: The specific reactant molecule upon which an enzyme acts.

Active Site: The region on the enzyme where substrate molecules bind and undergo a chemical reaction.

Catalysis:

The process of increasing the rate of a chemical reaction through the addition of a catalyst, such as an enzyme.