Enzymes and Metabolic Reactions

Enzymes

• Enzymes are globular proteins that act as catalysts, speeding up biochemical reactions.
• Enzymes are specific, meaning each enzyme catalyzes a specific reaction.
• Enzymes have an active site where the substrate binds.
• The lock-and-key model describes how the enzyme's active site and substrate fit together.
• The induced-fit model describes how the enzyme's active site changes shape slightly to accommodate the substrate.
• Enzymes lower the activation energy needed for a reaction to occur.
• Factors affecting enzyme activity include temperature and pH.

Metabolic Reactions

• Metabolism is the sum of all chemical reactions in a living organism.
• Anabolic reactions build complex molecules, while catabolic reactions break them down.
• These reactions may occur inside or outside cells.

Activation Energy

• Activation energy is the minimum energy required to initiate a chemical reaction.
• Enzymes lower activation energy, making reactions faster.
• The substrate's energy must be raised to an activated state for the reaction to proceed.

Enzyme Inhibition

• Competitive inhibitors compete with the substrate for the active site.
• Non-competitive inhibitors bind to a site other than the active site, changing its shape and altering its function.
• Increasing substrate concentration can counteract competitive inhibition.

Examples

• Oxygen (O2) and carbon dioxide (CO2) compete for the active site of an enzyme in photosynthesis.

This quiz covers the fundamental concepts of enzymes and their role in metabolic reactions. Explore the specifics of enzyme structure, function, and the factors affecting their activity. Additionally, learn about the distinction between anabolic and catabolic reactions along with the concept of activation energy.