Notes 2-4. Chemical Reactions and Enzymes

Transcription

1 Notes 2-4 Chemical Reactions and Enzymes

2 Chemical Reaction: A process that changes one set of chemicals into another set of chemicals Reactants: Elements entered into the reaction Products: Elements or Compounds produced by the reaction Always involves breaking old bonds and forming new ones! REACTANTS PRODUCTS

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4 Enzymes affect the reactions in living cells by changing the A. products of the reaction. B. speed of the reaction. C. temperature of the reaction. D. ph of the reaction. 0% 0% 0% 0% Answer Now 15

5 Energy in Reactions: Energy is either released or absorbed in chemical reactions Why? Because bonds are formed or broken! The energy needed to get a reaction started is called Activation Energy

6 Chemical reactions inside living things have 2 main problems! -Chemical reactions in living things are too slow -Some have a high activation energy -Solution: catalysts

7 Enzymes Catalyst: A substance that speeds up the rate of chemical reactions by lowering the activation energy required for the reaction to occur. Enzymes: Proteins that act as biological catalysts. Enzymes speed up chemical reactions within the cell.

8 Enzymes

9 Detailed Animation

10 What is the term used to describe the energy needed to get a reaction started? A. adhesion energy B. activation energy C. cohesion energy D. chemical energy 0% 0% 0% 0% Answer Now 15

11 Enzyme-Substrate Complex: How an Enzyme Works Substrates (reactants) bind to an enzyme s active site Active site lowers the activation energy = reaction happens faster Active site?

12 Enzymes-Substrate Complex When the substrate binds to the enzyme at the active site the catalytic action of the enzyme converts the substrate to the product Enzymes usually end in -ase Copy the equation below: SUBSTRATE(S) enzyme PRODUCT(S)

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14 What is the definition of an active site? A. The final product of an enzyme catalyzed reaction B. The spot on the substrate where the enzyme binds to C. The spot on the enzyme where the substrate binds to D. None of the above 0% 0% 0% 0% Answer Now 15

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16 An enzyme s is the molecule upon which an enzyme acts. A. active site B. inhibitor C. Catalyst D. substrate 0% 0% 0% 0% Answer Now 15

17 Remember Enzymes provide an active site where substrates can be brought together to react. Active site reduces the energy needed for a reaction The fit is like a lock and key Each enzyme (protein) has a specific shape Each substrate has a complementary shape The enzyme remains unchanged!

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19 Increasing the concentration of an enzyme s substrate (up to a point) would the reaction. A. speed up B. slow down C. inhibit D. destroy 0% 0% 0% 0% Answer Now speed up slow down inhibit destroy 15

20 Regulation of Enzyme Activity Enzymes can be affected by 2 Things: ph Temperature

21 Regulation of Enzyme Activity: Temperature Temperature A change in the optimal temperature can cause a protein to lose its shape = denaturing When an enzymes denatures, it loses its shape and cannot function properly anymore

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23 ph Regulation of Enzyme Activity: ph Each enzyme also has an optimal ph Usually ph of 6-8 Exceptions Pepsin (digestive enzyme in your stomach) -ph 2

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25 According to Figure 2 3, which enzyme has an optimum temperature of 40 C? A. enzyme X B. enzyme Y Answer Now 0% 0% enzyme X enzyme Y 15

26 Which of the following might be an enzyme? A. Sucrose B. Glucose C. Glycogen D. Amalase 0% 0% 0% 0% Answer Now 15

27 Enzymes Enzymes Enzymes The shape Which of the following statements about enzymes is NOT true? A. Enzymes work best at a specified ph. B. Enzymes are lipids. C. Enzymes are proteins. D. The shape of an enzyme allows it to do its job. 0% 0% 0% 0% Answer Now 15

28 The speed or rate of a chemical reaction is influenced by all of the following except. A. the concentration of the reactants B. the presence of catalysts or enzymes C. the presence or absence of carbon D. the temperature 0% 0% 0% 0% Answer Now 15

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