2. Aim: What are enzymes? I. Enzymes (Organic Catalysts) – proteins that change the rate of a chemical reaction (usually speeds it up). A. Characteristics of Enzymes 1. Enzymes are specific – they have specific shapes and only work on particular substrates.

3. a. Substrate – the substance an enzyme acts upon. Ex: The enzyme maltase only works on the substrate maltose. 2. Enzymes are named after the substrate they act upon. Ex: Lactase works on lactose, lipase works on lipids, and etc. ASE ending

4. 3. Enzyme Substrate Complex – when enzyme and substrate are fitted together to perform a reaction.

5. a.The substrate changes in a specific way. b.The enzyme does not change and can be used over and over to work on the same substrate. 4. Lock and Key Model – The fit of the substrate in the active site resembles the fit of a key in a lock.

6. Why can’t Lipase work on Maltose? Which enzyme would work on the substrate sucrose? What is the Lock and Key Model?