1. © 2010 Pearson Education, Inc.  Functions of cells  The sum total of all chemical reactions that occur in organisms is called “metabolism”  More specifically, building proteins and other products is called anabolism  Breaking molecules down is called catabolism  Enzymes are used to lower the activation energy for reactions to occur, thereby using less energy  Remember, enzymes catalyze specific reactions

2. Figure 5.00

3. © 2010 Pearson Education, Inc. SOME BASIC ENERGY CONCEPTS Energy makes the world go around. But what is energy? We need to discuss energy because that’s what cells use to run themselves and ultimately the organism which they comprise The first rule of energy is: ENERGY CAN NEITHER BE CREATED NOR DESTROYED – this is known as a principle called “conservation of energy” So what does that mean? Well, the suggestion is that the Universe has all of the energy that it will ever have, no more, no less.

4. © 2010 Pearson Education, Inc. Conservation of Energy Energy is defined as the capacity to perform work. Kinetic energy is the energy of motion. Potential energy is stored energy.

5. Climbing the steps converts kinetic energy of muscle movement to potential energy. On the platform, the diver has more potential energy. Diving converts potential energy to kinetic energy. In the water, the diver has less potential energy. Figure 5.1

6. © 2010 Pearson Education, Inc. Machines and organisms can transform kinetic energy to potential energy and vice versa. In all such energy transformations, total energy is conserved. –Energy cannot be created or destroyed. –This is the principle of conservation of energy.

7. © 2010 Pearson Education, Inc. Remember calories?  The small calorie or gram calorie (symbol: cal) is the approximate amount of energy needed to raise the temperature of one gram of water by one degree Celsius at a pressure of one atmosphere.  The large calorie, kilogram calorie, dietary calorie, nutritionist's calorie, nutritional calorie, Calorie (capital C) or food calorie (symbol: Cal) is approximately the amount of energy needed to raise the temperature of one kilogram of water by one degree Celsius.  The large calorie is thus equal to 1000 small calories or one kilocalorie (symbol: kcal). These are food calories on food labels  So ten kilocalories are equivalent to how many calories?

8. © 2010 Pearson Education, Inc. Cellular Respiration  Cellular Respiration (covered in next chapter) is the process of converting the energy stored in food molecules to energy stored in ATP  An adaptation of animal cells for increasing the surface area for more cellular respiration to occur is the cristae of a mitochondria

9. © 2010 Pearson Education, Inc. Entropy Every energy conversion releases some randomized energy in the form of heat. Entropy is a scientific concept that measures disorder: the higher the entropy, the higher the disorder. Unless energy is added, entropy will take over and the energy in the system will decrease. It’s like a log decaying in the woods. Heat is a –Type of kinetic energy –Product of all energy conversions

10. © 2010 Pearson Education, Inc. Scientists use the term entropy as a measure of disorder, or randomness. All energy conversions increase the entropy of the universe. This is theory of course and recent advancements in physics tend to support an alternate theory that order dominates the universe, not randomness. However, just focus on entropy and just remember that there are other ideas out there and lots for you to discover

11. © 2010 Pearson Education, Inc. Chemical Energy Molecules store varying amounts of potential energy in the arrangement of their atoms. (in the bonds between molecules or atoms) Organic compounds are relatively rich in such chemical energy.

12. © 2010 Pearson Education, Inc. Living cells and automobile engines use the same basic process to make chemical energy do work.

13. 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

14. © 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 perform useful work, such as the contraction of muscles and sending action potentials (electrical currents) in nerves Do you remember carbohydrates? Well, carbohydrates come from plants. Photosynthesis in particular. They take carbon dioxide from the atmosphere along with water and sunlight, and make fruits and vegetables! Whoa!

15. © 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.

16. (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

17. © 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

18. © 2010 Pearson Education, Inc. ATP is a nucleotide! Oh yeah, I know what that is. –Acts like an energy shuttle –Stores energy obtained from food –Releases it later as needed

19. © 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 –Watch This: http://youtu.be/5GMLIMIVUvohttp://youtu.be/5GMLIMIVUvo

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

21. © 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

22. ATP ADP P P P P P P P PXXY Y (a) Motor protein performing mechanical work (b) Transport protein performing transport work (c) Chemical reactants performing chemical work Solute Solute transported Protein moved Product madeReactants Transport protein Motor protein Figure 5.5

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

24. © 2010 Pearson Education, Inc. Activation Energy Activation energy –Activates the reactants –Triggers a chemical reaction Enzymes lower the activation energy for chemical reactions. Watch this: http://youtu.be/ok9esggzN18http://youtu.be/ok9esggzN18

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

26. © 2010 Pearson Education, Inc. Induced Fit Every enzyme is very selective, catalyzing a specific reaction.

27. © 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.

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

29. Active site Enzyme (sucrase) Sucrase can accept a molecule of its substrate. Substrate (sucrose) Substrate binds to the enzyme. Figure 5.9-2

30. 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 Figure 5.9-3

31. 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

32. © 2010 Pearson Education, Inc. Enzyme Inhibitors Enzyme inhibitors can prevent metabolic reactions by binding to the active site. An enzyme inhibitor is a molecule that binds to an enzyme and decreases its activity. Since blocking an enzyme's activity can kill a pathogen or correct a metabolic imbalance, many drugs are enzyme inhibitors. They are also used in pesticides.

33. (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

34. © 2010 Pearson Education, Inc. Other enzyme inhibitors –Bind at a remote site –Change the enzyme’s shape –Prevent the enzyme from binding to its substrate

35. © 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

36. Cell signaling Attachment to the cytoskeleton and extracellular matrix Enzymatic activity Cytoskeleton Cytoplasm Transport Fibers of extracellular matrix Intercellular joining Cell-cell recognition Figure 5.11

37. © 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.

38. © 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. Watch This: http://youtu.be/LeS2-6zHn6Mhttp://youtu.be/LeS2-6zHn6M

39. 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

40. © 2010 Pearson Education, Inc. Some substances do not cross membranes spontaneously. –These substances can be transported via facilitated diffusion. –Specific transport proteins act as selective corridors. –No energy input is needed.

41. © 2010 Pearson Education, Inc. Osmosis and Water Balance The diffusion of water across a selectively permeable membrane is osmosis. If diffusion is the movement of a solute, osmosis is the movement of water (solvent)

42. Hypotonic solutionHypertonic solution Sugar molecule Selectively permeable membrane Osmosis Figure 5.13-1

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

44. © 2010 Pearson Education, Inc. 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.

45. © 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

46. © 2010 Pearson Education, Inc. Plant have rigid cell walls. Plant cells require a hypotonic environment, which keeps these walled cells turgid. Watch this: http://youtu.be/rMGH1-mpp8ghttp://youtu.be/rMGH1-mpp8g Water Balance in Plant Cells

47. 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

48. © 2010 Pearson Education, Inc. As a plant cell loses water, –It shrivels. –Its plasma membrane may pull away from the cell wall in the process of plasmolysis, which usually kills the cell.

49. Figure 5.15

50. Active Transport: The Pumping of Molecules Across Membranes Active transport requires energy to move molecules across a membrane. Watch this: http://youtu.be/RPAZvs4hvGAhttp://youtu.be/RPAZvs4hvGA © 2010 Pearson Education, Inc.

51. Lower solute concentration Higher solute concentration ATP Solute Figure 5.16-1

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

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

54. Outside of cell Cytoplasm Plasma membrane Figure 5.17

55. © 2010 Pearson Education, Inc. Endocytosis takes material into a cell within vesicles that bud inward from the plasma membrane.

56. Figure 5.18

57. © 2010 Pearson Education, Inc. There are three types of endocytosis: –Phagocytosis (“cellular eating”); a cell engulfs a particle and packages it within a food vacuole. Ex: the act of a white blood cell engulfing a bacteria is phagocytosis –Pinocytosis (“cellular drinking”); a cell “gulps” droplets of fluid by forming tiny vesicles –Receptor-mediated endocytosis; a cell takes in very specific molecules

58. © 2010 Pearson Education, Inc. The Role of Membranes in Cell Signaling The plasma membrane helps convey signals between –Cells –Cells and their environment

59. © 2010 Pearson Education, Inc. Receptors on a cell surface trigger signal transduction pathways that –Relay the signal –Convert it to chemical forms that can function within the cell –Watch this: http://youtu.be/qOVkedxDqQohttp://youtu.be/qOVkedxDqQo

60. Outside of cellCytoplasm ReceptionTransductionResponse Receptor protein Epinephrine (adrenaline) from adrenal glands Plasma membrane Proteins of signal transduction pathway Hydrolysis of glycogen releases glucose for energy Figure 5.19

61. Evolution Connection: The Origin of Membranes Phospholipids –Are key ingredients of membranes –Were probably among the first organic compounds that formed before life emerged –Self-assemble into simple membranes © 2010 Pearson Education, Inc.

62. 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

63. ExocytosisEndocytosis Figure 5.UN04