Overview
This lecture explains what enzymes are, how they function as catalysts in biological reactions, and the factors that affect their activity, using relatable analogies and examples.
Enzyme Structure and Function
- Most enzymes are proteins that speed up chemical reactions in the body.
- Enzymes have a specific region called the active site, where substrates (reactant molecules) bind.
- The active site is uniquely shaped for its specific substrate, leading to precise binding.
- Induced fit means the active site can change shape slightly to better fit the substrate.
- When substrates bind to the active site, enzymes can build up or break down these molecules into products.
- Enzymes are catalysts, meaning they are not used up during reactions and can be reused.
Examples of Enzyme Activity
- Lactase is an enzyme that breaks down lactose (a sugar) into smaller, digestible parts.
- People lacking enough lactase are lactose intolerant and have difficulty digesting foods with lactose.
- Other digestive enzymes include lipase (breaks down fats), amylase (breaks down starch), and protease (breaks down proteins).
Enzyme Helpers
- Cofactors and coenzymes assist enzymes in catalyzing reactions by binding to the substrate or active site.
Enzyme Conditions and Denaturation
- Each enzyme works best at specific temperature and pH conditions.
- Extreme changes in these conditions can denature enzymes, distorting their shape and preventing them from functioning.
Key Terms & Definitions
- Enzyme — protein that speeds up chemical reactions by acting as a biological catalyst.
- Active Site — region on an enzyme where the substrate binds.
- Substrate — molecule that an enzyme acts upon.
- Induced Fit — the active site changes shape to better fit the substrate.
- Catalyst — substance that speeds up a reaction without being consumed.
- Cofactor/Coenzyme — helper molecules that assist enzyme function.
- Denature — loss of enzyme shape and function due to unfavorable conditions.
Action Items / Next Steps
- Review the functions of major digestive enzymes.
- Learn the ideal temperature and pH ranges for key enzymes.
- Prepare to define terms and explain enzyme action on the next quiz.