Transcript Enzymes
Enzymes Ch. 5.5 REVIEW Type of Molecule Carbs Components Large Molecule Name Starch, Sugar molecules Polysaccharides monosaccharides Lipids Triglyceride backbone Amino acids Glycogen cellulose 3 fatty acids 3-carbon glycerol Proteins Example protein Saturated and unsaturated fats Hair, muscles Objectives 1. Explain how enzymes affect activation energy 2. Describe how shape is important to function 3. Understand lactose intolerance Chemical Reactions • Each of our cells is like a mini chemical factory performing thousands of different reactions. • As a cell’s needs change, reactions speed up and slow down Activation Energy • In order for a chemical reaction to take place, bonds must be weakened • Need some type of “start up” energy • Activation Energy: – Start up energy --> activates reactants – i.e., candle and a match Activation Energy • What’s one way to speed things up, or provide activation energy? • Heat! Catalysts • Heating up molecules speeds things up, but what’s wrong with this? • Causes unnecessary reactions to occur • We use catalysts instead • Catalyst: – Compounds that speed up chemical reactions Enzymes • Enzymes: – Specialized proteins that are catalysts • Enzymes do NOT supply energy. They lower energy requirement barrier • Allow reactions to occur at cell’s normal temperature. Why is this important? • Online Activity 5.5 QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. How Enzymes Work • Very specific – Performs ONLY one function – Structure and shape essential to its function – Substrate binds to enzyme – Lock and key demo • Enzymes not changed by reactions – Can perform function over and over – BUT, pH and temperature CAN affect enzyme • Enzyme Animation! QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Got Lactase? • What does it mean to be “lactose intolerant?” QuickTime™ and a Sorenson Video 3 decompressor are needed to see this picture. Checkpoint • Explain the role of activation energy in a reaction. How does an enzyme affect activation energy? – Activation energy is the energy needed for the reaction to begin An enzyme affects activation energy by lowering it • How many times can an enzyme perform a reaction? – Unlimited!