Final answer:
Enzymes are biological catalysts that speed up chemical reactions by lowering the activation energy needed for the reaction to proceed. They work specifically on their substrates and are influenced by factors like temperature and pH, which can affect their structure and function. Unlike inorganic catalysts, enzymes are large protein molecules that are crucial for metabolic processes in living organisms.
Step-by-step explanation:
An enzyme and a catalyst are not exactly the same, although they both speed up chemical reactions. A catalyst is a general term that applies to any substance that increases the rate of a reaction without being consumed in the process. An enzyme, on the other hand, is a specific type of protein that acts as a biological catalyst within living organisms, facilitating and controlling metabolic pathways.
The main physical activity by which an enzyme speeds up a reaction is by lowering the activation energy required for the reaction to proceed. Activation energy is the minimum amount of energy needed to start a chemical reaction. Enzymes achieve this by binding to their specific substrates at their active site, creating an induced fit which places stress on chemical bonds, thus facilitating the reaction.
There are important variables that affect enzyme activity, including temperature, pH, substrate concentration, and the presence of inhibitors or activators. At high temperatures, enzymes can become denatured, meaning their three-dimensional structure is altered and they lose functionality. Similarly, an enzyme's activity is affected by pH, and it works best at an optimum pH. If the pH level strays too far from the optimum, the enzyme can lose its ability to bind the substrate and catalyze the reaction effectively.