Enzymes

Definition

Enzymes are biological catalysts that speed up chemical reactions in living organisms without being consumed in the process. They are crucial for various metabolic processes, enabling life by lowering the activation energy required for reactions, thus increasing the rate at which these reactions occur. Enzymes are typically proteins, although some RNA molecules can also exhibit catalytic activity, showing their importance in biochemical pathways and cellular function.

5 Must Know Facts For Your Next Test

1. Enzymes work by binding to their specific substrates at the active site, forming an enzyme-substrate complex that facilitates the reaction.
2. Each enzyme is highly specific to its substrate, meaning it only catalyzes one type of reaction or acts on a particular substrate due to its unique active site shape.
3. Enzymes are affected by various factors including temperature, pH, and concentration of substrates or inhibitors, which can impact their activity and efficiency.
4. Some enzymes require cofactors, which are non-protein molecules or ions, to become active and perform their catalytic functions effectively.
5. The lock-and-key model and the induced fit model describe how enzymes interact with substrates; both models emphasize the specificity and adaptability of enzymes.

Review Questions

• How do enzymes facilitate biochemical reactions and what factors influence their activity?
  • Enzymes facilitate biochemical reactions by lowering the activation energy required for the reaction to occur, which allows the reaction to proceed faster. They achieve this by binding to substrates at their active sites and forming enzyme-substrate complexes. Factors such as temperature, pH levels, substrate concentration, and the presence of inhibitors or activators can significantly influence enzyme activity by altering their structure or availability.
• Compare and contrast the lock-and-key model and the induced fit model of enzyme action.
  • The lock-and-key model suggests that enzymes and substrates fit together perfectly like a key in a lock, indicating that the enzyme's active site is complementary to the substrate's shape. In contrast, the induced fit model proposes that when a substrate binds to an enzyme, it induces a change in the enzyme's shape to better fit the substrate. While both models illustrate how enzymes interact with substrates, the induced fit model accounts for more flexibility and adaptability in enzyme action.
• Evaluate the role of enzymes in metabolic pathways and their impact on cellular functions.
  • Enzymes play a critical role in metabolic pathways by catalyzing specific reactions needed for cellular functions, such as energy production, biosynthesis, and signal transduction. By facilitating these reactions efficiently, enzymes help maintain homeostasis within cells and allow for the regulation of metabolic processes in response to environmental changes. The malfunction or inhibition of enzymes can disrupt these pathways, leading to metabolic disorders or diseases, highlighting their importance in overall cellular health and function.

Related terms

substrate: The specific reactant molecule that an enzyme acts upon during a biochemical reaction.

active site:

The region on an enzyme where substrate molecules bind and undergo a chemical reaction.

catalysis: The process by which a catalyst, such as an enzyme, accelerates a chemical reaction.