chemical reactions & enzymes
DESCRIPTION
Chemical Reactions & Enzymes. Sections 2.4 & 2.5. 2.4 Chemical Reactions. Key Concept: Life depends on chemical reactions. Bonds break and form during chemical reactions. Chemical reactions change substances into different ones by breaking and forming chemical bonds. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Chemical Reactions & Enzymes](https://reader035.vdocuments.us/reader035/viewer/2022062222/56815ee6550346895dcd8f18/html5/thumbnails/1.jpg)
Sections 2.4 & 2.5
CHEMICAL REACTIONS &
ENZYMES
![Page 2: Chemical Reactions & Enzymes](https://reader035.vdocuments.us/reader035/viewer/2022062222/56815ee6550346895dcd8f18/html5/thumbnails/2.jpg)
2.4 Chemical Reactions•Key Concept:•Life depends on chemical reactions.
![Page 3: Chemical Reactions & Enzymes](https://reader035.vdocuments.us/reader035/viewer/2022062222/56815ee6550346895dcd8f18/html5/thumbnails/3.jpg)
Bonds break and form during chemical reactions.
•Chemical reactions change substances into different ones by breaking and forming chemical bonds.• Reactants are changed during a chemical reaction.• Products are made by a chemical reaction.
• Endothermic and Exothermic Reactions
![Page 4: Chemical Reactions & Enzymes](https://reader035.vdocuments.us/reader035/viewer/2022062222/56815ee6550346895dcd8f18/html5/thumbnails/4.jpg)
Chemical reactions release or absorb energy.
•Activation energy is the amount of energy that needs to be absorbed to start a chemical reaction
![Page 5: Chemical Reactions & Enzymes](https://reader035.vdocuments.us/reader035/viewer/2022062222/56815ee6550346895dcd8f18/html5/thumbnails/5.jpg)
Exothermic reactions release more energy than they absorb.
• Reactants have higher bond energies than products.• Excess energy is released by the reaction.• Energy “exits” the reaction. (Exo = exit) Ex: Cellular
Respiration, making ice cubes
![Page 6: Chemical Reactions & Enzymes](https://reader035.vdocuments.us/reader035/viewer/2022062222/56815ee6550346895dcd8f18/html5/thumbnails/6.jpg)
Endothermic reactions absorb more energy than they release.•Reactants have lower bond energies than products.•Energy is absorbed by the reaction to make up the difference.•Energy goes into the reaction. (Endo = “into”) Ex: Photosynthesis, melting ice cubes
![Page 7: Chemical Reactions & Enzymes](https://reader035.vdocuments.us/reader035/viewer/2022062222/56815ee6550346895dcd8f18/html5/thumbnails/7.jpg)
STOP & REVIEW• _________ __________change substances into different ones by breaking and forming chemical bonds.• Chemical Reactions• _____________ are changed during a chemical reaction.• Reactants• __________ are made by a chemical reaction.• Products• ___________ ____________ is the amount of energy that needs to be absorbed to start a chemical reaction.• Activation Energy• ______________ reactions release more energy than they absorb.• Exothermic• ___________ reactions absorb more energy than they release.• Endothermic
![Page 8: Chemical Reactions & Enzymes](https://reader035.vdocuments.us/reader035/viewer/2022062222/56815ee6550346895dcd8f18/html5/thumbnails/8.jpg)
2.5 Enzymes•Key Concept:•Enzymes are catalysts for chemical reactions in living things.
![Page 9: Chemical Reactions & Enzymes](https://reader035.vdocuments.us/reader035/viewer/2022062222/56815ee6550346895dcd8f18/html5/thumbnails/9.jpg)
A catalyst lowers activation energy.•Catalysts are substances that speed up chemical reactions•Decrease activation energy• Increase reaction rate
![Page 10: Chemical Reactions & Enzymes](https://reader035.vdocuments.us/reader035/viewer/2022062222/56815ee6550346895dcd8f18/html5/thumbnails/10.jpg)
Enzymes allow chemical reactions to occur under tightly controlled
conditions.•Enzymes are catalysts in living things.•Enzymes are needed for almost all processes.•Most enzymes are proteins.
![Page 11: Chemical Reactions & Enzymes](https://reader035.vdocuments.us/reader035/viewer/2022062222/56815ee6550346895dcd8f18/html5/thumbnails/11.jpg)
Disruptions in homeostasis can prevent enzymes from
functioning.•Enzymes function best in a small range of conditions.•Changes in temperature or pH can break hydrogen bonds.•An enzyme’s function depends on its structure.
![Page 12: Chemical Reactions & Enzymes](https://reader035.vdocuments.us/reader035/viewer/2022062222/56815ee6550346895dcd8f18/html5/thumbnails/12.jpg)
An enzyme’s structure allows only certain reactants to bind to the
enzyme.•Substrates: reactants that bind to an enzyme•Active site: area on the enzyme where substrates bind
![Page 13: Chemical Reactions & Enzymes](https://reader035.vdocuments.us/reader035/viewer/2022062222/56815ee6550346895dcd8f18/html5/thumbnails/13.jpg)
Lock and key model shows how enzymes function
•Substrates are brought together at the active site of the enzyme•Enzyme weakens the bonds between the substrates.•Reaction forms a product that is released from the enzyme.
![Page 14: Chemical Reactions & Enzymes](https://reader035.vdocuments.us/reader035/viewer/2022062222/56815ee6550346895dcd8f18/html5/thumbnails/14.jpg)
STOP & REVIEW• _________ are catalysts for chemical reactions in living things.• Enzymes• ________ are substances that speed up chemical reactions by• Catalysts• Decreasing __________ ______• Activation energy• Increasing ___________ _______• Reaction rate• Most enzymes are _______________• proteins• Changes in __________ or _____ can break hydrogen bonds.• Temperature or pH• An enzyme’s function depends on its _________• Structure
• __________: reactants that bind to an enzyme• Substrates• ________ _____: area on the enzyme where substrates bind• Active Site