Ch.2-4 Chemical Reactions & Enzymes Chemistry of life

POINT > Define chemical reaction POINT > Distinguish exothermic and endothermic reactions POINT > Define activation energy POINT > Describe the role of enzymes and enzyme regulation

POINT > Define chemical reaction A chemical reaction is a process that changes one set of chemicals into another Reactants – Products – C6H12O6 + 6O2  6CO2 + 6H2O Substances that enter into a reaction Substances produced by a reaction

WB CHECK: C6H12O6 + 6O2  6CO2 + 6H2O What is one product in the chemical reaction shown above?

POINT > Distinguish exothermic and endothermic Exothermic reactions release energy The products have less energy than the reactants Usually involves breaking down molecules and bonds C6H12O6 + 6O2  6CO2 + 6H2O

POINT > Distinguish exothermic and endothermic Endothermic reactions absorb energy. The products have more energy than the reactants Usually involves building molecules 6CO2 + 6H2O  C6H12O6 + 6O2

WB CHECK: When you exercise, your muscle cells break down glycogen into glucose, then break down glucose to get energy (aerobic respiration). Are those reactions exothermic or endothermic? After intense exercise your muscle cells may need repairs. Do you think the “repair” reactions are exothermic or endothermic?

POINT > Define activation energy Most reactions need a little “push” to get started The activation energy is the amount of energy needed to get a reaction started

POINT > Describe the role of enzymes and enzyme regulation Enzymes are proteins that speed up the rate of a reaction. They are biological catalysts A catalyst is something that speeds up a reaction Enzymes work by lowering the activation energy The substrate is the reactant that the catalyst binds to

How do enzymes increase reaction rates in cells? WB CHECK > How do enzymes increase reaction rates in cells? What is the molecule an enzyme binds to called? What is a catalyst? https://www.youtube.com/watch?v=r1ryDVgx0zw

POINT > Describe the role of enzymes and enzyme regulation Enzymes make life possible! The thousands of reactions happening in cells every second would be too slow without them Enzymes can increase reaction rates by x 10,000,000! Many diseases, such as Alzheimers, Parkinsons, and many others are caused by faulty enzymes

POINT > Describe the role of enzymes and enzyme regulation Substrates bind to the active site of the enzyme Enzymes and substrates fit together precisely, like lock & key

POINT > Describe the role of enzymes and enzyme regulation Many factors influence enzyme activity: Temperature pH Concentration of substrate Other molecules

Homework Read pp 50-53 # 1-3 page 53 Pre-read 3.1 Ecology Quiz coming on Chapters 1-2