1. © 2010 Pearson Education, Inc. Lectures by Chris C. Romero, updated by Edward J. Zalisko PowerPoint ® Lectures for Campbell Essential Biology, Fourth Edition – Eric Simon, Jane Reece, and Jean Dickey Campbell Essential Biology with Physiology, Third Edition – Eric Simon, Jane Reece, and Jean Dickey Chapter 5 The Working Cell

2. © 2010 Pearson Education, Inc. Entropy Every energy conversion releases some randomized energy in the form of heat. Heat is a –Type of kinetic energy –Product of all energy conversions

3. © 2010 Pearson Education, Inc. Chemical Energy Molecules store varying amounts of potential energy in the arrangement of their atoms. Organic compounds are relatively rich in such chemical energy.

4. Fuel rich in chemical energy Energy conversion Waste products poor in chemical energy Gasoline  Oxygen Carbon dioxide  Water Energy conversion in a car Energy for cellular work Energy conversion in a cell Heat energy Heat energy Carbon dioxide  Water Food  Oxygen Combustion Cellular respiration Kinetic energy of movement ATP Figure 5.2

5. © 2010 Pearson Education, Inc. Cellular respiration is the energy-releasing chemical breakdown of fuel molecules that provides energy for cells to do work. Humans convert about 40% of the energy in food to useful work, such as the contraction of muscles.

6. © 2010 Pearson Education, Inc. Food Calories A calorie is the amount of energy that raises the temperature of one gram of water by 1 degree Celsius. Food Calories are kilocalories, equal to 1,000 calories. Filling this cube = 1 gram of water

7. (a) Food Calories (kilocalories) in various foods (b) Food Calories (kilocalories) we burn in various activities Cheeseburger Spaghetti with sauce (1 cup) Pizza with pepperoni (1 slice) Peanuts (1 ounce) Apple Bean burrito Fried chicken (drumstick) Garden salad (2 cups) Popcorn (plain, 1 cup) Broccoli (1 cup) Baked potato (plain, with skin) Food Calories Food 295 241 220 193 181 166 81 56 189 31 25 Activity Food Calories consumed per hour by a 150-pound person* 979 510 490 408 204 73 61 245 28 Running (7min/mi) Sitting (writing) Driving a car Playing the piano Dancing (slow) Walking (3 mph) Bicycling (10 mph) Swimming (2 mph) Dancing (fast) *Not including energy necessary for basic functions, such as breathing and heartbeat Figure 5.3 1 peanut has 5 kcal or 5 Cal So 1 peanut has enough energy in it to raise 1 kg of water by 5 0 C.

8. © 2010 Pearson Education, Inc. ATP AND CELLULAR WORK Chemical energy is –Released by the breakdown of organic molecules during cellular respiration –Used to generate molecules of ATP

9. © 2010 Pearson Education, Inc. The Structure of ATP ATP (adenosine triphosphate) –Consists of adenosine plus a tail of three phosphate groups –Is broken down to ADP and a phosphate group, releasing energy

10. TriphosphateDiphosphate Adenosine Energy ATPADP PPPPPP Phosphate (transferred to another molecule) Figure 5.4

11. © 2010 Pearson Education, Inc. Phosphate Transfer ATP energizes other molecules by transferring phosphate groups. This energy helps cells perform –Mechanical work –Transport work –Chemical work

12. © 2010 Pearson Education, Inc. The ATP Cycle Cellular work spends ATP. ATP is recycled from ADP and a phosphate group through cellular respiration. A working muscle cell spends and recycles about 10 million ATP molecules per second.

13. Cellular respiration: chemical energy harvested from fuel molecules Energy for cellular work ATP ADP P Figure 5.6

14. © 2010 Pearson Education, Inc. ENZYMES Metabolism is the total of all chemical reactions in an organism. Most metabolic reactions require the assistance of enzymes, proteins that speed up chemical reactions.

15. © 2010 Pearson Education, Inc. Activation Energy Activation energy –Activates the reactants –Triggers a chemical reaction Enzymes lower the activation energy for chemical reactions.

16. (a) Without enzyme (b) With enzyme Reactant Products Activation energy barrier Activation energy barrier reduced by enzyme Enzyme Energy level Figure 5.7

17. © 2010 Pearson Education, Inc. Induced Fit Every enzyme is very selective, catalyzing a specific reaction. Protease Lactase Maltase Sucrase Lipase Chitinase “ase”

18. © 2010 Pearson Education, Inc. Each enzyme recognizes a substrate, a specific reactant molecule. –The active site fits to the substrate, and the enzyme changes shape slightly. –This interaction is called induced fit. Enzymes can function over and over again, a key characteristic of enzymes.

19. Figure 5.9-1 Active site Enzyme (sucrase) Sucrase can accept a molecule of its substrate.

20. Active site Enzyme (sucrase) Sucrase can accept a molecule of its substrate. Substrate (sucrose) Substrate binds to the enzyme. The enzyme catalyzes the chemical reaction. H2OH2O Fructose Glucose The products are released. Figure 5.9-4

21. © 2010 Pearson Education, Inc. Enzyme Inhibitors Enzyme inhibitors can prevent metabolic reactions by binding to the active site.

22. (a) Enzyme and substrate binding normally (b) Enzyme inhibition by a substrate imposter (c) Enzyme inhibition by a molecule that causes the active site to change shape Substrate Active site Inhibitor Enzyme Figure 5.10

23. © 2010 Pearson Education, Inc. MEMBRANE FUNCTION Working cells must control the flow of materials to and from the environment. Membrane proteins perform many functions. Transport proteins –Are located in membranes –Regulate the passage of materials into and out of the cell

24. © 2010 Pearson Education, Inc. Passive Transport: Diffusion across Membranes Molecules contain heat energy that causes them to vibrate and wander randomly. Diffusion is the tendency for molecules of any substance to spread out into the available space.

25. © 2010 Pearson Education, Inc. Passive transport is the diffusion of a substance across a membrane without the input of energy. Diffusion is an example of passive transport. Substances diffuse down their concentration gradient, a region in which the substance’s density changes. H L

26. Molecules of dyeMembrane (a) Passive transport of one type of molecule (b) Passive transport of two types of molecules Net diffusion Equilibrium Net diffusion Equilibrium Net diffusion Equilibrium Figure 5.12

27. © 2010 Pearson Education, Inc. Osmosis and Water Balance The diffusion of water across a selectively permeable membrane is osmosis.

28. Hypotonic solutionHypertonic solution Sugar molecule Selectively permeable membrane Osmosis Figure 5.13-1 A hypertonic solution has a higher concentration of solute. A hypotonic solution has a lower concentration of solute. An isotonic solution has an equal concentration of solute.

29. Hypotonic solutionHypertonic solution Sugar molecule Selectively permeable membrane Osmosis Isotonic solutions Osmosis Figure 5.13-2

30. © 2010 Pearson Education, Inc. Osmoregulation is the control of water balance within a cell or organism. Most animal cells require an isotonic environment. Water Balance in Animal Cells

31. © 2010 Pearson Education, Inc. Plant have rigid cell walls. Plant cells require a hypotonic environment, which keeps these walled cells turgid. Water Balance in Plant Cells

32. Animal cell Plant cell Normal Flaccid (wilts) Lysing Turgid Shriveled Plasma membrane H2OH2O H2OH2O H2OH2OH2OH2O H2OH2O H2OH2O H2OH2O H2OH2O (a) Isotonic solution (b) Hypotonic solution (c) Hypertonic solution Figure 5.14

33. Figure 5.15

34. Active Transport: The Pumping of Molecules Across Membranes Active transport requires energy to move molecules across a membrane. L H © 2010 Pearson Education, Inc.

35. Lower solute concentration Higher solute concentration ATP Solute Figure 5.16-2

36. Exocytosis and Endocytosis: Traffic of Large Molecules Exocytosis is the secretion of large molecules within vesicles. © 2010 Pearson Education, Inc.

37. Outside of cell Cytoplasm Plasma membrane Figure 5.17

38. © 2010 Pearson Education, Inc. Endocytosis takes material into a cell within vesicles that bud inward from the plasma membrane.

39. Figure 5.18

40. © 2010 Pearson Education, Inc. Examine the cells below. Cells with a higher concentration of ions than the surrounding medium tend to ___. A) stay about the same size and shape B) expand C) shrink D) divide E) merge with other cells

41. Passive Transport (requires no energy) Active Transport (requires energy) DiffusionFacilitated diffusionOsmosis Higher solute concentration Lower solute concentration Higher water concentration (lower solute concentration) Lower water concentration (higher solute concentration) Solute Higher solute concentration Lower solute concentration ATP Solute Water Solute MEMBRANE TRANSPORT Figure 5.UN03