Enzymes Flashcards
What are enzymes?
Enzymes are biological catalysts that can alter or speed up chemical reactions while remaining chemically unchanged.
What are the characteristics of enzymes?
- Speeds up chemical reactions
- Required in minute amounts
- Specific in action
What is the mode of action of an enzyme?
An enzyme has a specific 3D shape and a depression called an active site. Only the substrate with a 3D shape complementary to that of the active site can fit into the enzyme. This forms an enzyme-substrate complex. While the substrate is attached to the active site, chemical reaction occurs and the substrate is converted to the products. The products leave the active site and the enzyme remains unchanged.
What is the lock-and-key hypothesis?
The enzyme is the lock and the substrate is the key. The substrate fits into the enzyme like a key fits into a lock.
How are enzymes affected by temperature?
At low temperatures, the enzyme is not very active. As the temperature rises, enzyme activity increases. Usually, the enzyme is twice as active for every 10ºC rise in temperature, until the optimum temperature is reached. At the optimum temperature, the enzyme is most active and the rate of reaction is at its highest. Beyond its optimum temperature, high temperatures will cause the enzyme to unfold and lose its function. The enzyme becomes denatured and enzyme activity decreases.
