Experiment 4 Enzyme Activity PDF

Experiment 4 Enzyme Activity GENERAL BIOLOGY LABORATORY Introduction to Enzymes Enzymes are biological catalysts that speed up chemical reactions in living organisms without being consumed in the process. They are crucial for maintaining life, as they regulate virtually every biochemical reacti...

Experiment 4 Enzyme Activity GENERAL BIOLOGY LABORATORY Introduction to Enzymes Enzymes are biological catalysts that speed up chemical reactions in living organisms without being consumed in the process. They are crucial for maintaining life, as they regulate virtually every biochemical reaction that occurs in cells Enzymes are proteins, typically made up of long chains of amino acids folded into complex 3D structures. Mostly proteins, with some RNA- based enzymes (ribozymes) Enzymes are often named by adding “-ase” Example: Dehydrogenase: An enzyme that removes hydrogen Enzyme Specificity Each enzyme typically acts on a specific substrate or type of substrate, ensuring that reactions are precisely controlled. This specificity is due to the unique shape and chemical properties of the enzyme's active site, which only allows certain substrates to bind. Enzyme Parts Active Site: It is a specific region on the enzyme where the substrate binds and where the chemical reaction occurs. Substrate: While not part of the enzyme itself, the substrate is the molecule or molecules that the enzyme acts upon. Enzyme Parts Enzyme-substrate complex: When a substrate binds to the active site, it forms an enzyme-substrate complex, which then undergoes a chemical transformation. Products: The end result of the reaction. Function and Mechanism Enzymes work by lowering the activation energy of a reaction. Activation energy is the initial energy required for a reaction to proceed. By reducing this energy, enzymes make it easier and faster for reactions to happen. Example Proteases: break peptide bonds in proteins. Amylases: catalyze the hydrolysis of starch. Catalase: breaks down H₂O₂. Factors Affecting Enzyme Activity Enzyme activity is influenced by several factors, which can affect the rate at which enzymes catalyze reactions. Here are the key factors: 1. Substrate Concentration 2. Enzyme Concentration 3. Temperature 4. pH 5. Presence of Cofactors and Coenzymes 6. Presence of Inhibitors or Activators Concentration of Enzymes and Substrates Increasing the concentration of substrates or enzymes can influence reaction rates up to a saturation point. Concentration of Enzymes and Substrates Low Concentration: When substrate concentration is low, the reaction rate is low because there are fewer substrate molecules available to bind with enzyme molecules. Increasing Concentration: As substrate concentration increases, the reaction rate increases because more substrate molecules can collide with enzyme molecules. Saturation Point: Eventually, a point of saturation is reached where all enzyme active sites are occupied, and adding more substrate won’t increase the reaction rate. Concentration of Enzymes and Substrates Increasing the concentration of enzymes will increase the reaction rate, provided there is an excess of substrate available. More enzymes mean more available active sites for substrates, thus more reactions occurring. Like substrate concentration, enzyme concentration has a limit. When there’s a limited amount of substrate, increasing enzyme concentration further will not increase the reaction rate. Temperature Optimal Temperature: Each enzyme has an optimal temperature at which it functions most efficiently, usually around the body temperature of the organism it belongs to (e.g., 37°C for human enzymes). Temperature Increase: Raising the temperature increases molecular movement, leading to more frequent collisions between the enzyme and substrate, thus increasing reaction rates. Temperature Denaturation: If the temperature is too high, enzymes can denature, meaning they lose their shape and functionality because the bonds holding the enzyme’s structure together are disrupted. pH Enzymes also have an optimal pH at which they work best. This pH varies widely among enzymes, depending on their environment (e.g., stomach enzymes like pepsin work best in acidic conditions, while others like trypsin function optimally in neutral or basic conditions). pH Deviations from Optimal pH: Changes in pH can disrupt ionic bonds and hydrogen bonds within the enzyme, altering its shape and, in particular, the active site. If the pH is too far from the enzyme’s optimal range, the enzyme may denature. The Practical Work Catalase is an enzyme found in nearly all living organisms, where it plays a crucial role in breaking down hydrogen peroxide (H₂O₂) —a potentially harmful byproduct of metabolism—into harmless water (H₂O) and oxygen (O₂). In our lab, potatoes will be the source of catalase Catalase activity as a function of substrate concentration Catalase activity as a function of temperature Catalase activity as a function of pH Things to note Hydrogen peroxide is a toxic chemical that can burn skin Immediately rinse any spills with water Wash hands before leaving the lab THANK YOU