Chemical Reactions and Enzymes

1. Chemical Reactions and Enzymes

2. Chemical Reactions • A chemical reaction is a process that changes one set of chemicals into another set of chemical. • The elements or compounds that enter into a chemical reaction are known as the reactants. • The elements or compounds produced by a chemical reaction are known as products.

3. Energy in Reactions • Chemical reactions can either release energy or absorb energy. • An exergonic reaction releases energy and will often occur spontaneously. • An endogonic reaction absorbs energy and will not occur spontaneously. • Which of the following reactions are exergonic?

4. Activation energy is the energy required to get a chemical reaction started. Burning glucose (sugar): an exergonic reaction high high activation energy needed to ignite glucose glucose activation energy from light captured by photosynthesis glucose + O2 energy content of molecules energy content of molecules net energy captured by synthesizing glucose energy released by burning glucose CO2 + H2O CO2 + H2O low low progress of reaction progress of reaction Photosynthesis: an endergonic reaction

5. A Catalyst is a substance that speeds of the rate of a chemical reaction high activation energy without catalyst activation energy with catalyst energy content of molecules reactants Enzymes are proteins that act as biological catalyst products low progress of reaction

6. Enzymes provide a site where reactants can be brought together and aligned properly to react. - the reactants of an enzyme catalyzed reaction.

7. substrates active site of enzyme enzyme

8. Enzyme structure substrate active site enzyme allosteric regulatory site Allosteric inhibition allosteric regulator molecule Competitive inhibition Regulation of Enzyme Activity • pH • Temperature • “on” or “off” keys (binding proteins) Up: Enzyme “off” Down: Enzyme “on” Competitive- key Fits lock, but wont Open door Up: Enzyme “off”