Overview
This lecture explains the role and function of enzymes in living cells, focusing on how they increase reaction rates and describing two key models of enzyme action.
Importance of Enzymes
- Enzymes speed up essential chemical reactions in living cells that would otherwise occur too slowly.
- Raising temperature to speed up reactions is impractical because it uses excessive energy and can harm cells and cause unwanted reactions.
- Catalysts are substances that increase reaction speed without being changed or used up, allowing repeated use.
- Enzymes are biological catalysts produced by living organisms.
Structure and Function of Enzymes
- Enzymes are large proteins made of long chains of amino acids folded into unique shapes.
- Each specific enzyme shape determines which chemical reaction it catalyzes.
- Enzymes have a region called the active site, which has a shape complementary to specific substrates (reactants).
- Only substrates that fit the active site can be catalyzed, making enzymes highly specific.
Models of Enzyme Action
- The lock and key model suggests substrates fit perfectly into the enzyme's active site, like a key in a lock.
- The induced fit model states the enzyme changes shape slightly when binding the substrate, allowing a snugger fit.
- In both models, the active site is described as complementary in shape to the substrate.
Key Terms & Definitions
- Enzyme — a protein that acts as a biological catalyst made by living organisms.
- Catalyst — a substance that increases the rate of a reaction without being changed or used up.
- Active Site — the specific region of an enzyme where substrates bind and reactions are catalyzed.
- Substrate — the reactant(s) that an enzyme acts on.
- Lock and Key Model — a model where the substrate fits perfectly into the enzyme's active site.
- Induced Fit Model — a model where the enzyme's active site changes shape to fit the substrate more closely.
Action Items / Next Steps
- Review the lesson and complete associated practice questions provided in the linked learning platform or lesson description.