CAMPBELL BIOLOGY CONCEPTS CONNECTIONS NINTH EDITION Power Point

CAMPBELL BIOLOGY: CONCEPTS & CONNECTIONS, NINTH EDITION Power. Point Lectures Chapter 5 The Working Cell TAYLOR SIMON DICKEY HOGAN REECE © 2018 Pearson Education, Inc. Lecture by Edward J. Zalisko

ENERGY AND THE CELL © 2018 Pearson Education, Inc.

5. 11 Chemical reactions either release or store energy • Exergonic reactions release energy. • Endergonic reactions require energy and yield products rich in potential energy. • Metabolism encompasses all of a cell’s chemical reactions. © 2018 Pearson Education, Inc.

Figure 5. 11 a Potential energy of molecules Reactants © 2018 Pearson Education, Inc. Amount of energy released Energy Products

Figure 5. 11 b Potential energy of molecules Products Energy Reactants © 2018 Pearson Education, Inc. Amount of energy required

Figure 5. 12 a_1 Triphosphate Adenosine P ATP © 2018 Pearson Education, Inc. P P

Figure 5. 12 a_2 Triphosphate H 2 O Adenosine P ATP © 2018 Pearson Education, Inc. P P Diphosphate Adenosine ADP P P + Phosphate Energy

Figure 5. 12 b Chemical work P ATP ADP + P P + Reactants Product formed Transport work ATP ADP + P P P Transport protein Solute transported Mechanical work ADP ATP Motor protein © 2018 Pearson Education, Inc. ADP + P P Protein filament moved

Figure 5. 12 c ATP synthesis requires energy ATP Energy from cellular respiration Energy for cellular work ADP + P © 2018 Pearson Education, Inc. ATP hydrolysis releases energy

HOW ENZYMES FUNCTION © 2018 Pearson Education, Inc.

5. 13 Enzymes speed up the cell’s chemical reactions by lowering energy barriers • Enzymes are protein catalysts that decrease the activation energy needed to begin a reaction. © 2018 Pearson Education, Inc.

Figure 5. 13_1 Activation energy barrier Enzyme Reactant Products Reaction without enzyme © 2018 Pearson Education, Inc. Energy Reactant Activation energy barrier reduced by enzyme Products Reaction with enzyme

5. 14 A specific enzyme catalyzes each cellular reaction • An enzyme’s substrate fits specifically in its active site. 1 The enzyme is available with an empty active site Substrate (sucrose) Active site Enzyme (sucrase) © 2018 Pearson Education, Inc. 2 The substrate enters the active site, which enfolds the substrate with an induced fit

Figure 5. 14_1 1 The enzyme is available with an empty active site Active site Enzyme (sucrase) © 2018 Pearson Education, Inc.

Figure 5. 14_2 1 The enzyme is available with an empty active site Substrate (sucrose) Active site Enzyme (sucrase) © 2018 Pearson Education, Inc. 2 The substrate enters the active site, which enfolds the substrate with an induced fit

Figure 5. 14_3 1 The enzyme is available with an empty active site Substrate (sucrose) Active site 2 The substrate enters the active site, which enfolds the substrate with an induced fit Enzyme (sucrase) H 2 O 3 The substrate is converted to products © 2018 Pearson Education, Inc.

Figure 5. 14_4 1 The enzyme is available with an empty active site Substrate (sucrose) Active site Glucose 2 The substrate enters the active site, which enfolds the substrate with an induced fit Enzyme (sucrase) Fructose H 2 O 4 The products are released © 2018 Pearson Education, Inc. 3 The substrate is converted to products

5. 14 A specific enzyme catalyzes each cellular reaction Checkpoint question Explain how an enzyme speeds up a specific reaction. © 2018 Pearson Education, Inc.

5. 15 Enzyme inhibition can regulate enzyme activity in a cell • A competitive inhibitor competes with the substrate for the active site. • A noncompetitive inhibitor alters an enzyme’s function by changing its shape. • Feedback inhibition helps regulate metabolism. © 2018 Pearson Education, Inc.

Figure 5. 15 a Substrate Active site Enzyme Normal binding of substrate Competitive inhibitor Noncompetitive inhibitor Enzyme inhibition © 2018 Pearson Education, Inc.

Figure 5. 15 b D – Feedback inhibition A Enzyme 1 Reaction 1 Starting molecule © 2018 Pearson Education, Inc. B Enzyme 2 Reaction 2 Enzyme 3 C Reaction 3 D Product Intermediate molecules

5. 15 Enzyme inhibition can regulate enzyme activity in a cell Checkpoint question Explain an advantage of feedback inhibition to a cell. © 2018 Pearson Education, Inc.

5. 16 CONNECTION: Many drugs, pesticides, and poisons are enzyme inhibitors • Many beneficial drugs act as enzyme inhibitors. © 2018 Pearson Education, Inc.

5. 16 CONNECTION: Many drugs, pesticides, and poisons are enzyme inhibitors • Enzyme inhibitors have also been developed as • pesticides and • deadly poisons for chemical warfare. Checkpoint question What determines whether enzyme inhibition is reversible or irreversible? © 2018 Pearson Education, Inc.

You should now be able to 1. Describe the fluid mosaic structure of cell membranes. 2. Describe the diverse functions of membrane proteins. 3. Relate the structure of phospholipid molecules to the structure and properties of cell membranes. 4. Define diffusion and describe the process of passive transport. © 2018 Pearson Education, Inc.

You should now be able to 5. Explain how osmosis can be defined as the diffusion of water across a membrane. 6. Distinguish between hypertonic, hypotonic, and isotonic solutions. 7. Explain how transport proteins facilitate diffusion. 8. Distinguish between exocytosis, endocytosis, phagocytosis, and receptor-mediated endocytosis. © 2018 Pearson Education, Inc.

You should now be able to 9. Define and compare endergonic and exergonic reactions. 10. Explain how ATP functions as an energy shuttle. 11. Explain how enzymes speed up chemical reactions. 12. Explain how competitive and noncompetitive inhibitors alter an enzyme’s activity. 13. Explain how certain drugs, pesticides, and poisons can affect enzymes. © 2018 Pearson Education, Inc.