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# Enzymes and Catalysis ## Activation Energy Enzymes are special proteins that help chemical reactions occur in cells more efficiently. They do this by lowering the activation energy needed to initiate the reaction. - **Activation Energy:** Imagine rolling a boulder up a hill. The required ene...

# Enzymes and Catalysis ## Activation Energy Enzymes are special proteins that help chemical reactions occur in cells more efficiently. They do this by lowering the activation energy needed to initiate the reaction. - **Activation Energy:** Imagine rolling a boulder up a hill. The required energy to get it over the hill is the activation energy. The boulder, by itself, will only roll down hill; it won't automatically roll up. - **How Enzymes Help:** Enzymes work by creating a path to the "bottom" of the hill. This path requires less energy to traverse than the initial hill, letting the reaction begin. Essentially, enzymes lower the energy barrier, facilitating the reaction to happen. - **Example:** Hydrogen peroxide (H₂O₂) gradually breaks down into water (H₂O) and oxygen (O₂) with some activation energy. With a catalyst like manganese dioxide (MnO₂), the process speeds up, as can be seen when it is added to hydrogen peroxide solution. The inclusion of an enzyme, like catalase, speeds up the reaction even further, often causing it to proceed with a noticeable foam. ## Catalysts Catalysts speed up chemical reactions without being consumed by the reaction themselves. - **Inorganic Catalysts:** Substances such as MnO₂ may facilitate different reactions. - **Enzymes:** Often much more efficient than inorganic catalysts for particular reactions. ## Enzyme Function - **Specificity:** Most enzymes catalyze only one, or at most two, reactions. - **Role in Reactions:** Enzymes are affected by pH and temperature. Optimal pH levels usually exist around 7 (neutral) on a typical pH scale. High or low temperatures/pH can denature an enzyme, causing it to lose its shape and ability to function. - **Relationship with pH and Temperature:** The speed of an enzyme-catalyzed reaction is greatly affected by temperature and pH. The two graphs on your document illustrate this relationship.