1. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings PowerPoint Lectures for Biology: Concepts and Connections, Fifth Edition – Campbell, Reece, Taylor, and Simon Lectures by Chris Romero Chapter 5 The Working Cell

2. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 1/18/11 – “A” Day Objective: To understand how energy is transformed and used in the cell Do Now: What has more energy stored ATP, ADP or AMP? How is this energy released and “recharged”

3. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 1/18/11 – “A” Day Objective: To understand how energy is transformed and used in the cell Do Now: What does it mean when something is “phosphorylated”?

4. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 1/19/11 – “B” Day Objective: To understand how energy is transformed and used in the cell Do Now: What does it mean when something is “phosphorylated”? TODAY –Do you have your course selection form –POGIL –Rxn in a bag

5. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 1/19/11 – “B” Day Objective: To understand how energy is transformed and used in the cell Do Now: What is an anabolic reaction? Catabolic? Which is endothermic? Exothermic? TODAY –Do you have your course selection form –POGIL –Rxn in a bag

6. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Cool “Fires” Attract Mates and Meals Fireflies use light to send signals to potential mates –Instead of using chemical signals like most other insects

7. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The light comes from a set of chemical reactions –That occur in light-producing organs at the rear of the insect

8. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Females of some species –Produce a light pattern that attracts males of other species, which are then eaten by the female

9. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings ENERGY AND THE CELL 5.1 Energy is the capacity to perform work All organisms require energy –Which is defined as the capacity to do work

10. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Kinetic energy is the energy of motion Potential energy is stored energy –And can be converted to kinetic energy Figure 5.1A–C

11. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 5.2 Two laws govern energy transformations Thermodynamics –Is the study of energy transformations

12. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The First Law of Thermodynamics According to the first law of thermodynamics –Energy can be changed from one form to another –Energy cannot be created or destroyed Figure 5.2A

13. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The Second Law of Thermodynamics The second law of thermodynamics –States that energy transformations increase disorder or entropy, and some energy is lost as heat Figure 5.2B Heat Chemical reactions ATP Glucose + Oxygen water Carbon dioxide + Energy for cellular work

14. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 5.3 Chemical reactions either store or release energy Endergonic reactions –Absorb energy and yield products rich in potential energy Figure 5.3A Potential energy of molecules Reactants Energy required Products Amount of energy required

15. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Exergonic reactions –Release energy and yield products that contain less potential energy than their reactants Figure 5.3B Reactants Energy released Products Amount of energy released Potential energy of molecules

16. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Cells carry out thousands of chemical reactions –The sum of which constitutes cellular metabolism Energy coupling –Uses exergonic reactions to fuel endergonic reactions

17. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 5.4 ATP shuttles chemical energy and drives cellular work ATP powers nearly all forms of cellular work

18. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The energy in an ATP molecule –Lies in the bonds between its phosphate groups Phosphate groups ATP Energy PPP P PP Hydrolysis Adenine Ribose H2OH2O Adenosine diphosphate Adenosine Triphosphate + + ADP Figure 5.4A

19. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings ATP drives endergonic reactions by phosphorylation –Transferring a phosphate group to make molecules more reactive Figure 5.4B ATP Chemical work Mechanical work Transport work P P P P P P P Molecule formedProtein moved Solute transported ADP + Product Reactants Motor protein Membrane protein Solute +

20. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings ATP ADP + P Energy for endergonic reactions Energy from exergonic reactions Phosphorylation Hydrolysis Cellular work can be sustained –Because ATP is a renewable resource that cells regenerate Figure 5.4C

21. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings HOW ENZYMES FUNCTION 5.5 Enzymes speed up the cell’s chemical reactions by lowering energy barriers

22. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings For a chemical reaction to begin –Reactants must absorb some energy, called the energy of activation Figure 5.5A E A barrier Reactants Products 12 Enzyme

23. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings A protein catalyst called an enzyme –Can decrease the energy of activation needed to begin a reaction Figure 5.5B Reactants E A without enzyme E A with enzyme Net change in energy Products Energy Progress of the reaction

24. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 5.6 A specific enzyme catalyzes each cellular reaction Enzymes have unique three-dimensional shapes –That determine which chemical reactions occur in a cell

25. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Figure 5.6 Enzyme (sucrase) Glucose Fructose Active site Substrate (sucrose) H2OH2O 1 Enzyme available with empty active site 2 Substrate binds to enzyme with induced fit 4 Products are released 3 Substrate is converted to products The catalytic cycle of an enzyme

26. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 5.7 The cellular environment affects enzyme activity Temperature, salt concentration, and pH influence enzyme activity Some enzymes require nonprotein cofactors –Such as metal ions or organic molecules called coenzymes

27. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 5.8 Enzyme inhibitors block enzyme action Inhibitors interfere with an enzyme’s activity

28. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings A competitive inhibitor –Takes the place of a substrate in the active site A noncompetitive inhibitor –Alters an enzyme’s function by changing its shape Figure 5.8 Substrate Enzyme Active site Normal binding of substrate Enzyme inhibition Noncompetitive inhibitor Competitive inhibitor

29. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings CONNECTION 5.9 Many poisons, pesticides, and drugs are enzyme inhibitors

30. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Endocytosis can occur in three ways –Phagocytosis –Pinocytosis –Receptor-mediated endocytosis Pseudopodium of amoeba Food being ingested Phagocytosis Pinocytosis Receptor-mediated endocytosis Material bound to receptor proteins PIT Cytoplasm Plasma membrane TEM 54,000  TEM 96,500  LM 230  Figure 5.19C

31. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 5.21 Chloroplasts and mitochondria make energy available for cellular work Enzymes are central to the processes that make energy available to the cell

32. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Chloroplasts carry out photosynthesis –Using solar energy to produce glucose and oxygen from carbon dioxide and water Mitochondria consume oxygen in cellular respiration –Using the energy stored in glucose to make ATP