Enzymes are biological molecules that act as catalysts to speed up chemical reactions in living organisms. Most enzymes are proteins, though some RNA molecules also have catalytic activity. They work by binding to specific molecules called substrates and lowering the activation energy required for a reaction to proceed, allowing the reaction to happen more readily than it would on its own. Enzymes are essential for processes like digestion, energy production, DNA replication, metabolism, and many other cellular functions. They are typically highly specific for their substrates and operate under optimal conditions of temperature and pH. Key points about what enzymes do:

• Accelerate chemical reactions: By lowering activation energy, making reactions occur faster than in the absence of the enzyme.

• Substrate specificity: Each enzyme binds to a particular substrate or set of related substrates at its active site, like a lock and key or induced-fit model.

• Regulation and reuse: Enzymes are not consumed in the reactions they catalyze and can be reused multiple times; their activity is often regulated by cellular signals and inhibitors.

• Roles across systems: Enzymes participate in digestion (breakdown of carbohydrates, fats, and proteins), energy production, DNA replication and repair, toxin breakdown in the liver, blood clotting, and many other essential processes.

If you’d like, I can tailor this to a specific context (e.g., digestion, metabolism, or a particular organism) or provide simple diagrams or analogies to illustrate enzyme action.