How Would You Make A Cake? Ingredients Stuff to make the cake Add energy mix and bake it Have a completed Yummy cake product.

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

Vocabulary Energy Reactant Product Activation Energy Enzyme Active State Substrate

Changing Matter 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.

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 change).

What types of change happened here? B

Observe Chemical Changes Changes in color Formation of a gas Formation of a precipitate.

Changing Matter, continued There are many other constants in the natural world = Universal Laws Law of conservation of mass. Matter is neither created nor destroyed in any change. This means that any new forms of matter comes from existing matter! Entropy. As the number of reactions increase, the amount of chaos in the universe increases.

Changing Matter, continued Law of conservation of energy. Energy may change from one form to another, but the total amount of energy does not change. This means that any new types of energy comes from energy that has already been here…just in a different form. Where does this energy come from?... Bonds being broken…such as when food is broken down. Or from heat…from the sun, the Earth’s core, or some other produced source (fires, etc.)

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.

Visual Concept: Types of Energy

Changing Matter, continued With every change, really called a reaction, the total amount of usable energy decreases because some energy is given off to the surroundings as heat. & Living things get the energy needed for life processes through different chemical reactions that happen inside of the body.

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. 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.

Reactants to Products Reactants Products Reaction

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.

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

Chemical Reactions, continued 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.

Reaction with the correct activation energy

Visual Concept: Activation Energy and Chemical Reactions

Activation Energy 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. Sometimes this happens with stirring… = physical Sometimes this happens with heating… = thermal

Chemical Reactions, continued 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.

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

Biological Reactions In living things, like our bodies, chemical reactions occur between large, complex biomolecules. They are happening all the time…millions of reactions per second in every cell. Many of these reactions require large activation energies. Enzymes help reactions happen that may not normally happen or may take too long to happen unaided.

Biological Reactions, continued 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.

Effect of Enzyme on Activation Energy

Biological Reactions, continued 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.

Enzyme Action Click to animate the image.

Enzyme Action Enzyme Right Orientation Product AB Reactant A Wrong Orientation = NO REACTION Right Orientation Product AB Reactant A Reactant B

Biological Reactions, continued 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. Every 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?

Biological Reactions, continued 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.

Concept Check Where is the active site? Where are the reactants? A B C 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

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. Your experiment involves having a lactose intolerant individual consume milk & the enzyme. You need to analyze the results. The data from your experiment looks like this… Digestive Enzyme

Chemical Reactions Analyze the illustration of experimental data that tests whether a digestive enzyme supplement works. In-class/Homework Questions: Answer these questions. Due:_______ Pts:_____/25 Sick/Intolerant Healthy/Tolerant What do the curved arrows represent? What does the dotted line represent? What part of a reaction is A? What are B & C? How does the 2nd and 3rd reactions differ? Which reaction (2 or 3) would you think uses an enzyme? What does the enzyme do? Which reaction gives off heat to the environment? (remember conservation of energy) If the reactions are drugs, which product does a better job, 2 or 3? Extra Credit***: Explain what this experiment did. What is ‘C’?

What do the curved arrows represent? 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: Reactant 4. B & C: Products 5. The 3rd reaction takes less activation energy. 6. Reaction 3 7. Lowers the activation energy and can speed up reactions. 8. A B 9. Reaction 3 because there’s less energy (heat) going into the environment. 10. This reaction shows how lactose can be digested in those lactose intolerant. C is the control. 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. How does the 2nd and 3rd reactions differ? 6. Which reaction (2 or 3) would you think uses an enzyme? 7. What does the enzyme do? 8. Which reaction gives off heat to the environment? 9. If the reactions are drugs, which product does a better job, 2 or 3? 10. Explain what this experiment did. What is ‘C’?

Chapter 3 Review: Answers 3. (Reactant = substrate)  product 4. Cohesion = attraction between like particles. Adhesion = attraction between different particles 5. Nucleic acids are made of nucleotides 6. D 7. D 8. B 9. C 10. A 11. B 12. C 13. D 14. 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 3 22. 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.

Chemical Reactions Analyze the illustration of a reaction Chemical Reactions Analyze the illustration of a reaction. In-class/Homework Questions: Answer these questions. Due:_______ Pts:_____/25 What do the curved arrows represent? What does the dotted line represent? What part of a reaction is A? What are B & C? How does the 2nd and 3rd reactions differ? Which reaction (2 or 3) would you think uses an enzyme? What does the enzyme do? Which reaction gives off heat to the environment? (remember conservation of energy) If the reactions are products, which product does a better job, 2 or 3? Extra Credit***: Explain what this experiment did. What is ‘C’?

Chemical Reactions Analyze the illustration of a reaction Chemical Reactions Analyze the illustration of a reaction. In-class/Homework Questions: Answer these questions. Due:_______ Pts:_____/25 What do the curved arrows represent? What does the dotted line represent? What part of a reaction is A? What are B & C? How does the 2nd and 3rd reactions differ? Which reaction (2 or 3) would you think uses an enzyme? What does the enzyme do? Which reaction gives off heat to the environment? (remember conservation of energy) If the reactions are products, which product does a better job, 2 or 3? Extra Credit***: Explain what this experiment did. What is ‘C’?

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)

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 _____?

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.