Energy, Chemical Reactions, and Enzymes

Energy the ability to move or change matter found in many forms can be converted from one form into another

Chemical Reactions process that changes one set of chemicals into another always involves changes in the chemical bonds that join the atoms in the compounds

Chemical Reactions H2CO3 H2O CO2 reactants substances that enter into a chemical reaction  found on the left side of the arrow products substances produced by the chemical reaction found on the right side of the arrow H2CO3 H2O CO2 + carbon dioxide plus water forms carbonic acid

Energy in Reactions some chemical reactions release energy and others absorb energy energy changes are an important factor in determining whether a reaction will occur

Exothermic chemical reaction that releases energy C → A + B + Energy

Endothermic chemical reaction that needs to absorb energy to begin A + B + Energy → C

Energy in Reactions Label each of the following reactions as either: Energy-Releasing Reaction or Energy-Absorbing Reaction (from Holt Biology, pg. 39)

Use the location of the REACTANTS and PRODUCTS to help.

Energy in Reactions

Energy in Reactions

Activation Energy energy needed to start a chemical reaction ex: spark plug in an engine

Hydrolysis of Sucrose by Sucrase Enzymes enzymes are biological catalysts catalyst substances that reduce the activation energy of a chemical reaction reducing activation energy allows the reaction to occur more frequently and faster Hydrolysis of Sucrose by Sucrase McGraw - Hill

Enzymes & Activation Energy Reaction pathway without enzyme Activation energy Activation energy with enzyme Reactants Products

What type of macromolecule are most enzymes? enzymes are proteins these proteins enzymes increase the speed of chemical reactions some enzymes break molecules apart

What type of macromolecule are most enzymes? enzymes are proteins these proteins enzymes increase the speed of chemical reactions some enzymes break molecules apart other enzymes put molecules together

What type of macromolecule are enzymes? enzymes are proteins these proteins enzymes increase the speed of chemical reactions some enzymes break molecules apart other enzymes put molecules together do not get used up in a chemical reaction help maintain homeostasis

Substrate substance on which an enzyme acts during a chemical reaction substrate = reactants

Active Site How Enzymes Work McGraw - Hill the location on an enzyme that attaches to a substrate How Enzymes Work McGraw - Hill

Enzyme Specificity enzymes are specific because only its substrate fits into its active site enzymes are similar to a lock and key

Enzyme Efficiency work well only within a certain set of conditions changes in conditions like pH and temperature can change the shape of the protein when the substrate no longer fits the active site, the enzyme will not work the “lock and key” no longer fit in one another

lactose  glucose + galactose Example lactase is an enzyme that breaks down milk sugar (lactose) lactase lactose  glucose + galactose

lactose  glucose + galactose Why is lactase written above the arrow and not included in the chemical equation? because enzymes (like lactase) are not used up in chemical reactions they can be re-used over and over again for the same type of reaction lactase lactose  glucose + galactose