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Chemical Reactions and Enzymes. Chapter 2-4 Notes. Chemical Reactions. Process that changes one set of chemicals into another. Reactants->>>>> Products Bonds break>> forming new bonds * Energy is released or absorbed whenever chemical bonds are formed or broken.
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Chemical Reactions and Enzymes Chapter 2-4 Notes
Chemical Reactions • Process that changes one set of chemicals into another. • Reactants->>>>> Products Bonds break>> forming new bonds * Energy is released or absorbed whenever chemical bonds are formed or broken.
Energy in Reactions • Reactions that release energy often occur spontaneously. • Reactions that absorb energy often will NOT occur unless energy is added.
Activation Energy • Energy needed to get the reaction started! • More energy need to get “Energy Absorbing Reaction” started!!!
How energy affects Reaction Rate Energy Absorbing Energy Releasing Products Activation energy Activation energy Reactants Reactants Products
Enzymes • Enzymes speed up reactions by lowering energy needs! • A catalyst • Is a chemical agent that speeds up a reaction without being consumed by the reaction • An enzyme • Is a catalytic protein…type of catalyst
Why do we need catalysts? • RECALL:Every chemical reaction between molecules • Involves both bond breaking and bond forming • An enzyme catalyzes reactions • By lowering the Activation Energy needed to start the reaction. http://www.lewport.wnyric.org/jwanamaker/animations.htm
Substrates and Enzymes • The substrate • Is the reactant an enzyme acts on • The enzyme • Binds to its substrate, forming an enzyme-substrate complex • Substrate specificity of enzymes varies • They sometimes catalyze chemically similar reactions
Water and Solutions • A solution is a mixture of two or more substances. • Water solutions are very important to living things! • The dissolved substance- SOLUTE • The substance that dissolves the solute- SOLVENT Ex. Salt and water…. Salt= Solute Water= Solvent
Cool Facts about Water • Cohesion- Water molecules stick together creating surface tension. • Expanding- water molecules spread a part as water freezes
Acids and Bases • If a compound is put in water, making a solution, the compound may break a part forming H+ ions this is called an acid. • A baseis a compound that makes OH- ions.
pH Scale • The way we measure the amount of hydrogen ions ( H+) in a solution. • Low pH (below 7) is acidic….lots of H+ • High pH (above 7) is basic….little H+ lots of OH-
Environmental Awareness • Rain water with a pH les than 5.6 is called acid rain. • Acid rain forms from pollution in the air. • Acid rain takes away good minerals from the soil and puts in harmful metals like Aluminum, which can kill plants. • Acid rain that flows into lakes and rivers can also kill fish.
Four Organic Macromolecules • Giant molecules • Formed by polymerization- small compounds join to form large compounds! • Smaller units- monomers • Larger units- polymers. **4 macromolecules: Carbohydrates, lipids, nucleic acids, and proteins.
Carbohydrates • 1. Made up of: carbon, hydrogen & oxygen • 2. Used for energy and structural purposes by living things. • 3. Examples: Starch (potatoes) Sugars Monosaccharide- single sugar (glucose) Polysaccharide- formed from monosaccharides (glycogen& cellulose)