Final answer:
Enzymes are not rigid and alter their shape slightly in an induced fit when substrates bind to their active sites. This interaction is specific yet flexible, allowing the enzyme to catalyze reactions efficiently without being consumed.
Step-by-step explanation:
An enzyme is not rigid and changes shape slightly when the substrate enters, a process known as induced fit.
Enzymes have specific active sites where substrates bind. This interaction is often compared to a lock and key. However, the more accurate model for many enzymes is the induced fit hypothesis, which allows the enzyme to adjust its shape to better interact with the substrate. This slight alteration of the enzyme's structure enables it to form an enzyme-substrate complex, facilitating the chemical reaction without altering the reaction's final free energy. After the reaction, the enzyme returns to its original form ready to catalyze another reaction.
Enzymes are highly specific and their specificity is attributed to the precise interaction between the enzyme and its substrate, but there is innate flexibility. This specificity and flexibility are essential for the enzyme's function as a biological catalyst, aiding in various biochemical reactions without being consumed or fundamentally changed in the process.