Chemical Reactions Biology Textbook Section 2-4

Chemical Reactions and Enzymes 1. chemical reaction: process that changes one set of compounds (reactants) into another set of compounds (products) example: ReactantsProducts CO 2 H2OH2O H 2 CO 3

2. Reactants: chemicals at the beginning of a chemical reaction: CO 2 + H 2 O 3. Products: chemicals at the end of a chemical reaction: C 6 H 12 O 6 + O 2 CO 2 H2OH2O H 2 CO 3

4. In the book it says that some chemical reactions happen slowly, while other reactions happen quickly. What example does the book give of a SLOW chemical reaction? Rust: Iron and Oxygen combine to form iron oxide. This can take a long time, maybe days, weeks or years.

5. Color 6. Name/Chem Formula 9. What are the reactants/products ? CO 2 H2OH2O H 2 CO 3 Carbon Dioxide + Water  Carbonic Acid

7. Where does this reaction take place? Carbon Dioxide + Water  Carbonic Acid CO 2 H2OH2O H 2 CO 3 Your Blood 8. What does this chemical rxn help us do? Dissolve more CO2 into blood to allow us to breath carbon out quickly.

10. Chemical Rxns involve changes in bonds, not changes in the amount of atoms. Carbon Dioxide + Water  Carbonic Acid CO 2 H2OH2O H 2 CO 3 Notice on both sides of the reaction there are 3 Oxygen, 2 Hydrogen and 1 Carbon atom. No atoms were lost, the bonds were just changed to form a new compound out of the old ones. Conservation of Matter: Atoms can NOT be created or destroyed, just rearranged.

Conservation of matter: During a chemical reaction, atoms are not created or destroyed – just rearranged. Therefore, chemical equations must be balanced so there is the same number of atoms on both sides of the equation. chemical equation: CO 2 + H 2 O  C 6 H 12 O 6 + O 2 balanced chemical equation 6CO 2 + 6H 2 O  C 6 H 12 O 6 + 6O 2

CO 2 + H 2 O  C 6 H 12 O 6 + O 2 chemical equation:

6CO 2 + 6H 2 O  C 6 H 12 O 6 + 6O 2 Balanced chemical equation:

Energy in Reactions: (Back of your paper) Energy is ______________________ or _______________________ whenever chemical bonds are _________________ or _____________________. Lets look at these TWO kinds of chemical reactions…. absorbed released Broken Formed

1. Chemical reactions that Absorb energy…. Endothermic Example: Photosynthesis Chemical Formula: 6CO 2 + 6H 2 O  C 6 H 12 O 6 + 6O 2 Explain: Will not occur without a source of energy. Reaction feels cold because energy (heat) is becoming bonds.

2. Chemical reactions that Release energy…. Exothermic Example: Forest Fire Chemical Formula: C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O Explain: Requires a tiny bit of energy to get started, but is fast and spontaneous. Feels hot because braking bonds releases energy into the environment.

Chemical Reactions and Enzymes Label the graph: EndothermicExothermic Reactants Products Activation Energy Activation energy Energy AbsorbingEnergy Releasing Reactants

Chemical Reactions and Enzymes Label the graph: EndothermicExothermic Explain: Products have more energy than the reactants. (Ex. Sugar from carbon dioxide) Explain: Reactants have more energy than the products (ex. smoke from burnt trees)

Chemical Reactions and Enzymes DRAWING: EndothermicExothermic

A. Catalyst: substance that speeds up a chemical reaction by lowering the activation energy Catalysts found in living things are called enzymes Increasing the Speed of Reactions: Some things make chemical reactions happen faster.

B. Enzymes (what macromolecule? ) Are found in all living things provide a site where the reactants of a chemical reaction can be brought together are not used up or changed during the chemical reaction Protein Speed of Reactions: Some things make chemical reaction faster.

active site: part of the enzyme where the reactants bind (stick) reactants: molecules at beginning of a chemical reaction. Called the substrate when they encounter an enzyme. substrate only fits into the active site of the correct enzyme (like a key and lock) III. Speed of Reactions: Some things make chemical reaction faster.

Labeled diagram: Enzyme Active Site Reactants

Enzyme Active Site Reactants III. How does an enzyme work? A. substrate binds to the enzyme Substrate

Enzyme Active Site III. How does an enzyme work? A. substrate binds to the enzyme Substrate

Enzyme Active Site III. How does an enzyme work? B. reactants converted to product Product

Enzyme Active Site III. How does an enzyme work? C. products are released – enzyme is free to bind new substrate Product

IV. Enzymes only work in specific conditions A.temperature: 1.Every enzyme works best in a specific temperature range. Ex: amylase 37°C Human body temp is 37°C

IV. Enzymes only work in specific conditions A.temperature: 2. TOO HOT = destroy enzyme (denaturing) Why does it stop the enzyme from working: Changes the shape of the active site

Enzyme Active Site TOO HOT: Product No Product Made

IV. Enzymes only work in specific conditions A.temperature: 3. Too cold= enzyme slows down the colder it gets Reptiles sit in the sun to warm enzymes

IV. Enzymes only work in specific conditions B. pH: changes the shape of the enzyme and its active site Example: Blood is a pH of 7.4 Remember Buffers! Really important for enzymes

Enzyme Active Site TOO Acidic or Basic: Product No Product Made

IV. Enzymes only work in specific conditions C. coenzymes: make enzymes work better Example: Vitamins! Vitamin C helps enzymes that make white blood cells work faster, so your immune system can fight off disease faster before you get really sick.

IV. Enzymes only work in specific conditions D. inhibitor molecules: block substrate from entering active site Example: poisons Arsenic blocks the enzyme ATP Synthase. Stops your body from making sugar into energy: quick death.

Enzyme Active Site Inhibitor Molecules: No Product made

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Enzyme Active Site Enzyme: Peroxidase in liver cells Reactants: Hydrogen peroxide Reactants Hydrogen Peroxide

Enzyme Active Site Enzyme: Peroxidase in liver cells Reactants: Hydrogen peroxide Reactants=Substrate

Enzyme Active Site Enzyme: Peroxidase in liver cells Products: Water and Oxygen Product O2O2 H2OH2O

Enzyme Active Site Product Enzyme: Peroxidase in liver cells Products: Water and Oxygen More Hydrogen Peroxide O2O2 H2OH2O