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2. Sucrose (C 12 H 22 O 11 ) Glucose (C 6 H 12 O 6 ) Fructose (C 6 H 12 O 6 ) Sucrase

3.  The initial energy required to start a chemical reaction  Activation energy is often supplied in the form of heat from the surroundings

4.  A catalyst is a chemical agent that speeds up a reaction without being consumed by the reaction  Works by lowering activation engery

5. Fig. 8-15 Progress of the reaction Products Reactants ∆G is unaffected by enzyme Course of reaction without enzyme Free energy E A without enzyme E A with enzyme is lower Course of reaction with enzyme

6.  Enzyme – biological catalyst; substrate specific; reusable  Substrate – the specific reactant for an enzyme; binds to enzyme  Active site – site on enzyme to which substrate binds – substrate specific

7.  Very specific  1 type of enzyme works with one substrate  Fit together perfectly

8.  When substrate and enzyme join the enzyme shape is modified  The enzyme wraps around the substrate  It is not rigid like metal

9. Fig. 8-17 Substrates Enzyme Products are released. Products Substrates are converted to products. Active site can lower E A and speed up a reaction. Substrates held in active site by weak interactions, such as hydrogen bonds and ionic bonds. Substrates enter active site; enzyme changes shape such that its active site enfolds the substrates (induced fit). Active site is available for two new substrate molecules. Enzyme-substrate complex 5 3 2 1 6 4