2. How Would You Make A Cake? IngredientsAdd energy Have a complete product Cake mix Mix & bake it Yummy cake

3. Objectives Identify where living things get energy. Understand how chemical reactions occur. Identify why enzymes are important to living things.

4. Vocabulary Energy Reactant Product Activation Energy Enzyme Active State Substrate

5. Living things are made of matter, which consists of a substance with a form. In the case of the living, this form is always changing. A constant in the natural world is that changes constantly occur. –Development –Seasons –Metabolism –Etc. Changing Matter

6. Changes Change usually comes in two forms: Physical: change occurs when only the form or shape of the matter changes (it looks different). Chemical: change occurs when a substance changes into a different substance (the molecules & atoms change).

7. What types of change happened here? A B

8. Energy The necessary ingredient of change is energy. Energy is the ability to move or change matter. Energy exists in many forms and can be converted from one form to another. Every change in matter requires a change in energy.

9. Forms of Energy Kinetic (Thermal Heat): Energy of motion Potential: Energy that can be used at a later time. Mechanical: Energy transferred in machines Electro-magnetic: Electrons transferring energy Nuclear: Energy stored in the nucleus of atoms Sound: Energy in waves Chemical: Energy stored in bonds

10. Changing Matter –Where does this energy come from?... –From heat…from the sun, the Earth’s core, or some other produced source (fires, etc.) –Or from bonds being broken…such as when food is broken down.

11. Chemical Reactions Changing a substance requires a chemical reaction. During this process, bonds between atoms are broken, and new ones are formed. –The bonds are usually through C to C bonds or P to P There are two parts of a reaction A reactant (aka substrate) is a substance that is changed in a chemical reaction –It’s all the stuff that you start with that mixes and mingles together. A product is a new substance that is formed. –This is the stuff that you end up with after the mingling.

12. Reactants to Products Reactants Products Reaction

13. Reactants to Products You will see several reactions in this course. They are written in the same form: Reactants  Products The arrow means “changes to” or “forms” Sometimes the arrow only goes one way (like from ingredients to cake) and sometimes the arrow goes both ways. When the arrow goes both directions it shows you that the reactants and products can switch positions… that the reaction can go both ways.

14. Building & Breaking The often see cycle of energy being stored and released. We need to eat because we lose a little with every reaction to entropy, heat lost to the universe that can’t be recovered.

15. Concept Check What are the two parts of a reaction and what are they called? Reactants & Products How do you show a reaction on paper? Reactants  Products

16. Activation Energy Going through a reaction, or going from reactants to products, can only occur under the right conditions. The right conditions to start a reaction involve overcoming the natural repulsion between their negatively charged electron clouds. Remember, like charges repel. The activation energy of a reaction is the minimum kinetic energy required to start a chemical reaction.

17. Reaction with the correct activation energy

18. Activation Energy: Energy of Matter One of the universal laws, stated by Sir Isaac Newton thousands of years ago, was that objects in motion stay in motion… Think of activation energy like motivation. When you are motivated to get off the couch and start chores or work out it’s like molecules getting the energy to react with each other… The energy for reactions comes from temperature or how much movement the molecules have…its kinetics. –Sometimes this happens with stirring… = physical –Sometimes this happens with heating…= thermal

19. Activation Energy: Alignment Alignment Sometimes, even if enough energy is available, the product still may not form. When the reactant particles collide, the correct atoms must be brought close together in the proper orientation. –Orientation means the correct parts of the molecules must meet up.

20. Activation Energy: Summation The point is… Chemical reactions can only occur when the activation energy is available and the correct atoms are aligned. Activation Energy

21. Biological Reactions… Enzymes Enzymes An enzyme is a protein that increases the speed of biochemical reactions. –Enzymes hold molecules close together and in the correct orientation. –As such, an enzyme lowers the activation energy of a reaction. –By assisting in necessary biochemical reactions, enzymes help organisms maintain homeostasis. In Essence: Enzymes help reactions happen that may not normally happen or may take too long to happen unaided.

22. Effect of Enzyme on Activation Energy

23. Chemistry of LifeSection 4 Endergonic = “energy in” Exergonic = “energy out”

24. Enzymes Each enzyme has an active site, the region where the reaction takes place. The shape of the active site determines which reactants, or substrates, will bind to it. Each different enzyme acts only on specific substrates. Binding of the substrates causes the enzyme’s shape to change. This change causes some bonds in the substrates to break and new bonds to form.

25. Enzyme Action Click to animate the image.

26. Enzyme Action Reactant AReactant B Enzyme Right Orientation Product AB Wrong Orientation = NO REACTION

27. Enzymes Many enzymes are proteins. One problem with proteins is that they change with temperature. Changes in temperature and pH can change a protein’s shape. Ever cook an egg? If an enzyme changes shape, it won’t work well. Most enzymes need a certain range of temperatures and pH. –What important property of life ensures this? –Homeostasis –What molecule help us maintain this in our bodies?

28. Enzymes & Metabolism Metabolism Cells get most of the energy needed for metabolism by breaking down food molecules. –What is metabolism again? –Sum of all chemical reactions in an organism. The release of energy from food molecules occurs in a series of reactions using many enzymes to capture energy in the form of ATP molecules. –ATP is what? –The energy transporter in the body. The enzymes reduce the activation energy so much that only a little energy is needed to start the reactions. In this process, very little energy is lost as heat.

29. Concept Check What is Activation Energy? The energy necessary to start a reaction. How are enzymes useful? They lower activation energy to allow chemical reactions to occur. Where is the active site? Where are the reactants? A B C

30. Case Study Some people cannot digest certain foods. For example, diabetics cannot digest sugars properly and those that are lactose-intolerant cannot digest milk. Science has been working tirelessly to help solve these problems but one can’t be too sure if the drug companies are honest. A certain company claims that their drug will help you digest carbohydrates better (like those to combat lactose-intolerance). You suspect the active ingredient in the product is an enzyme…lactase. In an attempt to prove the product’s claim you perform an experiment. Digestive Enzyme Your experiment involves 3 individuals; 1 individual with lactose intolerance and consuming milk, 1 person with normal lactose tolerance consuming milk, and 1 lactose intolerant individual consuming milk & the enzyme. You need to analyze the results.

31. Chemical Reactions Analyze the illustration of experimental data that tests whether a digestive enzyme supplement works. In-class : Answer these questions. 1.What do the curved arrows represent? 2.What does the dotted line represent? 3.What part of a reaction is A? 4.What are B & C? 5.Describe which reaction is which? 6.How do the 2 nd and 3 rd reactions differ? 7.Which reaction (2 or 3) would you think uses an enzyme? 8.What does the enzyme do? 9.Which reaction gives off heat to the environment? (remember conservation of energy) Sick/Intolerant Healthy/Tolerant

32. 1. The curved lines represent reactions over time.2. The difference between taking or giving heat in the reaction, but the line represents time. 3. A: Reactant4. B & C: Products 5. A  C in lactose intolerant, A  B is digesting lactose, 3 is with the enzyme 6. 3 has less activation energy. 7. Reaction 3 uses the enzyme because of the lowered activation energy. 8. Lowers the activation energy and can speed up reactions. 9. Reactions A  B (2 & 3).10. This reaction shows how lactose can be digested in those lactose intolerant. C is the control. 1.What do the curved arrows represent? 2. What does the dotted line represent? 3. What part of a reaction is A? 4. What are B & C? 7. Which reaction (2 or 3) would you think uses an enzyme? 9. Which reaction gives off heat to the environment? 10. Explain what this experiment did. What is ‘C’? 5. Describe which reaction is which. 8. What does the enzyme do? 6. How do the 2 nd and 3 rd reactions differ?

34. Chapter 3 Review: Answers 3. (Reactant = substrate)  product4. Cohesion = attraction between like particles. Adhesion = attraction between different particles 5. Nucleic acids are made of nucleotides6. D 7. D8. B9. C10. A 11. B12. C13. D14. B 15. Forming compounds can make atoms more stable b/c an atom is more stable when the valence shell is filled. 16. Adhesion and cohesion are responsible for water being able to climb up a plant stem. 17. Simple carbs have 1-2 sugar, complex have more than 2 18. Waxes are waterproof and can form protective coatings 19. Physical changes the way something looks, chemical changes the substance 20.In order for a reaction to occur, molecules must both be in the correct orientation and overcome the repulsion of like particles. 21. pH 322. The stomach is more acidic then the intestines. 23. There are only one type of atom in any single element. 24. They are more stable when they are covalently bonded together. They are molecules but not compounds b/c there is only one element 25. Ionic bonds are between ions that swap electrons where covalent is between atoms that share them. 26. The freezing point is dependent upon the H- bonds in water. Ions of salt disrupt them and the freezing point of water. 27. Balanced diets give you enough of the essential materials for life.

35. Identifying an Enzyme, Word Usage Breaking a word down In science, one can easily be confused in trying to find out what a molecule is or what it does Luckily scientists are smart people and developed patterns to be able to identify the type of word you are reading and what it may do. Remember: –-ose = sugar (Lactose, glucose), –-ol, -oid = lipid (cholesterol, glycerol)

36. Biological Reactions, continued Enzymes: An easy way to tell if a molecule is an enzyme is by the suffix. –Suffix is the word ending Enzymes start with what they do and usually end in –ase –Protease: Breaks down proteins –Lactase: Breaks down lactose to glucose & galactose –Lipase: Breaks down _____?

37. Summary Living things use different chemical reactions to get the energy needed for life processes. An activation energy is needed to start a chemical reaction. The reactants must also be aligned to form the product. By assisting in necessary biochemical reactions, enzymes help organisms maintain homeostasis.