First Five

1. First Five • Explain the meaning of the following terms: • enzyme • substrate • product • active site • denatured

2. What are Enzymes? • Globular proteins that act as biological catalysts to increase reactions rates • Catalysts: substances that speed up reactions w/o being consumed • Biological? Because they are proteins; NOT because they are alive (they aren’t!)

3. Enzymes: How they work speed up biochemical reactions by lowering the activation energy of reactions that would normally happen anyway.

4. Mode of Action • Enzymes bind substrates (enzyme reactant) into active sites (pocket or groove on enzyme). • While the enzyme and the substrate are joined, the enzyme catalyzes the reaction and converts the substrate to the product(s).

5. Enzymes • A classic example of an enzymatic reaction is the hydrolysis of sucrose into glucose and fructose.

6. Enzymes • Another look…

7. Practice Find the enzyme, substrate(s), and product(s) in the sentences. I) Acetylcholinesterasebreaks down acetylcholine into acetyl and choline. • Enzyme: ________________________ • Substrates: ______________________ • Products: _______________________ II) A disaccharide can be broken down into glucose and fructose by lysozyme • Enzyme: ________________________ • Substrates: ______________________ • Products: _______________________

8. Practice Find the enzyme, substrate(s), and product(s) in the sentences. I) Acetylcholinesterasebreaks down acetylcholine into acetyl and choline. • Enzyme: Acetylcholinesterase • Substrates: acetylcholine • Products: acetyl & choline II) A disaccharide can be broken down into glucose and fructose by lysozyme • Enzyme: lysozyme • Substrates: sucrose • Products: glucose & fructose

9. Factors Affecting Enzyme Activity

10. Factors Affecting Enzyme Activity: Rate of Reaction vsEnzyme Concentration Describe the activity of the enzyme as concentration of the enzyme increases. Enzyme activity increases as enzyme concentration increases. Eventually enzyme activity plateaus even though enzyme concentration continues to increase.

11. Factors Affecting Enzyme Activity: Rate of Reaction vs. Temperature Describe the activity of the enzyme as temperature increases. Increasing heat energy causes more collisions between enzyme and substrate, until an optimal temperature is reached. Above the optimal temperature, the enzyme denatures so the rate falls rapidly.

12. Factors Affecting Enzyme Activity: Rate of Reaction vs. pH Describe the activity of the enzyme as pH increases. Activity gradually increases up to the optimal pH and gradually decreases after the optimal pH.

13. Effects on Enzyme Activity • Rate of Enzyme Activity is influenced by: • Substrate concentration • more substrate = more activity until saturation • Amount of enzyme • more enzyme = more activity until saturation • Temperature • higher temperature = more activity until the enzyme’s protein denatures • pH • usually in range of 6-8 for enzymes in humans • Inhibitors • reduce activity by binding or changing shape of active sites

14. Two types of inhibitors • Competitive Inhibitor • When something besides the substrate blocks the active site • Noncompetitive Inhibitor • When a molecule binds to another spot on the enzyme causing it to change shape and become inactive

15. Enzyme Simulation • Rules: • Only do your action upon your substrate. • The starting substrate and ending product must match the picture on your enzyme’s instructions. • If you can’t operate upon a particular substrate, move it on to another person or another table.  • Enzyme E is the last step in the process.  Although the description only shows two of the monomers stuck on the pencil, it will continue adding more and more until it is full.