Chapter 8 Cellular Energy

2. Chapter 8 Cellular Energy Section 1: How Organisms Obtain Energy Section2: Photosynthesis Section 3: Cellular Respiration

3. Cellular Energy Chapter 8 8.1 How Organisms Obtain Energy Transformation of Energy • Energy is the ability to do work. • Thermodynamics is the study of the flow and transformation of energy in the universe.

4. Cellular Energy Chapter 8 8.1 How Organisms Obtain Energy Laws of Thermodynamics • First law—energy can be converted from one form to another, but it cannot be created nor destroyed. • Second law—energy cannot be converted without the loss of usable energy.

5. Energy in Matter • As we begin to look at the links between matter, NRG, and organization keep in mind that… • All matter contains NRG • Not all matter contains the same amount of NRG

6. Atoms • What do skin, plant roots, water vapor, and a plastic cell phone all have in common? • All are made of atoms • Atoms are the building blocks of matter • The organization of matter/atoms, determines the amount of energy in a given substance • All matter is composed of elements (types of matter) • An atom is the smallest particle of an element that still has the properties of that element

7. Elements • All matter is composed of elements (types of atoms) • An atom is the smallest particle of an element that still has the properties of that element • The properties of an element are the result of the number and type of subatomic particle • Electrons( - charged particle, outside the nucleus) • Protons (+ charged particle, nucleus) • Neutrons (no charge, nucleus)

8. Carbon vs Hydrogen Carbon Hydrogen 1 proton 1 electron 0 neutrons • 6 electrons • 6 protons • 6 neutrons

9. Matter and Energy are Related • The arrangement of atoms determine the characteristics of a particular type of matter • Skin vs cell phone • Arrangement of atoms in skin allows for flexibility and selective permeability • Arrangement of atoms in cell phone allows for rigid non-porous structure

10. Chemical Bonds • Chemical bonds hold atoms together in predictable ways to form molecules • Molecules are combinations of different atoms organized in unique ways through chemical bonds • Energy is stored within the structure of a molecule’s bonds and atoms • Example Magnets : • NRG or force attracts opposite ends to stick together • to pull apart takes force as well

11. Many Forms of Energy • Magnetic Energy • Heat Energy • Light Energy • Electrical Energy • Solar Energy • Nuclear Energy • Mechanical Energy • Chemical Energy

12. Energy in Chemical Reactions • Exothermic Reaction (exo=out, thermic=heat) • NRG is released when atoms in molecules are reorganized • Ex: explosive combustion of grain dust • Endothermic Reactions (endo=in, thermic=heat) • NRG needs to be taken in to reorganize atoms or molecules • Ex: breaking down water into molecules of H2 and O2

13. Rearranging Atoms • Rearranging chemical bonds through chemical reactions transfers the NRG stored in the matter • All living systems require matter and NRG • Matter and NRG are related because NRG is necessary to organize and reorganize matter continuously • Due to all of life’s adaptations over time, reactions that occur in living systems can happen in a controlled manner – without sparks or explosions

14. Cellular Energy Chapter 8 8.1 How Organisms Obtain Energy Autotrophs and Heterotrophs • Autotrophs are organisms that make their own food. • Heterotrophs are organisms that need to ingest food to obtain energy.

15. Cellular Energy Chapter 8 8.1 How Organisms Obtain Energy Metabolism • All of the chemical reactions in a cell • Photosynthesis—light energy from the Sun is converted to chemical energy for use by the cell • Cellularrespiration—organic molecules are broken down to release energy for use by the cell

16. Cellular Energy Chapter 8 8.1 How Organisms Obtain Energy ATP: The Unit of Cellular Energy • ATP releases energy when the bond between the second and third phosphate groups is broken, forming a molecule called adenosine diphosphate (ADP) and a free phosphate group.

17. ATP

18. Cellular Energy Chapter 8 8.2 Photosynthesis Overview of Photosynthesis • Photosynthesis occurs in two phases. • Light-dependent reactions • Light-independent reactions

19. Wavelengths of Light • Photosynthesis depends on the particular intensity of light • Works more or less efficiently depending on the intensity of light • Requirements of light intensity varies for different plants

20. Major Events in Plant Cells During Photosynthesis • Absorption of light energy • Conversion of light energy into chemical energy (ATP) • Storage of potential energy in carbohydrates All 3 of these events occur in two distinct phases

21. Cellular Energy Chapter 8 8.2 Photosynthesis Phase One: Light Reactions • The absorption of light is the first step in photosynthesis. • Chloroplasts capture light energy.

22. First Phase of Photosynthesis • Chlorophyll absorbs light energy • Enzymes use this energy to produce small energy carrying molecules • ATP • NADPH

23. Cellular Energy Chapter 8 8.2 Photosynthesis Electron Transport • Light energy excites electrons in photosystem II and also causes a water molecule to split, releasing an electron into the electron transport system, H+ into the thylakoid space, and O2 as a waste product.

24. Cellular Energy Chapter 8 8.2 Photosynthesis • The excited electrons move from photosystem II to an electron-acceptor molecule in the thylakoid membrane. • The electron-acceptor molecule transfers the electrons along a series of electron-carriers to photosystem I.

25. Cellular Energy Chapter 8 8.2 Photosynthesis • Photosystem I transfers the electrons to a protein called ferrodoxin. • Ferrodoxin transfers the electrons to the electron carrier NADP+, forming the energy-storing molecule NADPH. Visualizing Electron Transport

26. Second Phase of Photosynthesis • ATP and NADPH power the second phase • Carbon and oxygen from atmospheric carbon dioxide combine with hydrogen from water to form carbohydrates • Non-photosynthetic organisms use these carbohydrates when eating the photosynthetic organisms • Photosynthetic organisms use these molecules for long-term NRG storage • Similar to humans using glycogen for long-term NRG storage

27. Cellular Energy Chapter 8 8.2 Photosynthesis Phase Two: The Calvin Cycle • In the second phase of photosynthesis, called the Calvin cycle, energy is stored in organic molecules such as glucose.

28. Cellular Energy Chapter 8 8.2 Photosynthesis • Six CO2 molecules combine with six 5-carbon compounds to form twelve 3-carbon molecules called 3-PGA. • The chemical energy stored in ATP and NADPH is transferred to the 3-PGA (3-phosphoglycerate) molecules to form high-energy molecules called G3P (glyceraldehyde 3-phosphate).

29. Cellular Energy Chapter 8 8.2 Photosynthesis • Two G3P molecules leave the cycle to be used for the production of glucose and other organic compounds. • An enzyme called rubisco converts the remaining ten G3P molecules into 5-carbon molecules called RuBP. • These molecules combine with new carbon dioxide molecules to continue the cycle.

30. Cellular Energy Chapter 8 8.2 Photosynthesis Alternative Pathways • Many plants in extreme environments have alternative photosynthesis pathways to maximize energy conversion • C4 plants • An adaptive pathway used by plants to maintain photosynthesis and minimize water loss (sugar cane and corn) • Rearranges carbon atoms in a different way and closes stroma during the day • CAM plants • Another adaptive pathway used by plants to maximize photosythesis: Crassulacean Acid Metabolism (cacti, orchids, pinneapple) • CO2 only enters leaves at night which minimizes water loss

31. Cellular Energy Chapter 8 8.3 Cellular Respiration Overview of Cellular Respiration • Organisms obtain energy in a process called cellular respiration. • The equation for cellular respiration is the opposite of the equation for photosynthesis.

32. Cellular Energy Chapter 8 8.3 Cellular Respiration • Cellular respiration occurs in two main parts. • Glycolysis • Aerobic respiration

33. Cellular Energy Chapter 8 8.3 Cellular Respiration Glycolysis • Glucose is broken down in the cytoplasm through the process of glycolysis. • Two molecules of ATP and two molecules of NADH are formed for each molecule of glucose that is broken down.

34. 1. Glycolysis (glyco- sugar, lysis – split) • Splits glucose into 2 smaller molecules • Produces small amount of ATP

35. Cellular Energy Chapter 8 8.3 Cellular Respiration Krebs Cycle • Glycolysis has a net result of two ATP and two pyruvate. • Most of the energy from the glucose is still contained in the pyruvate. • The series of reactions in which pyruvate is broken down into carbon dioxide is called the Krebs cycle.

36. 2. The Krebs Cycle • Enzymes break down the 2 small molecules from glycolysis and convert them into carbon dioxide • This process produces several ATP NRG units • The CO2 that we exhale comes largely from the Krebs Cycle in cellular respiration

37. Cellular Energy Chapter 8 8.3 Cellular Respiration • The net yield from the Krebs cycle is six CO2 molecules, two ATP, eight NADH, and two FADH2.

38. Cellular Energy Chapter 8 8.3 Cellular Respiration Electron Transport • Final step in the breakdown of glucose • Point at which ATP is produced • Produces 24 ATP

39. 3. Electron Transport System • From the first two steps, there remains many left over hydrogen atoms • These hydrogen atoms are taken to hydrogen carrier molecules which take them to the electron transport system • NRG from the hydrogen atoms is transferred to ATP • Most ATP comes from this stage in cellular respiration

40. 3. Electron Transport System • Hydrogen atoms are split into electrons and protons • Electrons are taken to chain of electron carrier molecules embedded in the lining of the mitochondria • Electron carriers pass along the electrons and this process releases NRG at each step • Energy produced is used to pump protons across to the inner membrane • Finally, this NRG is harvested to convert NRG into ATP molecules

41. 3. Electron Transport System At the end of the process, electrons and protons are combined with O2 to form H2O

42. Cellular Energy Chapter 8 8.3 Cellular Respiration Anaerobic Respiration • The anaerobic pathway that follows glycolysis • Two main types • Lactic acid fermentation • Alcohol fermentation Cellular Respiration

43. Overall Production of Cellular Respiration… • Many ATP molecules (all stages) • Carbon dioxide (krebs cycle) • Water (electron transport system) Cells can use ATP directly for all cellular work (ex: muscle contraction)

44. Cellular Energy Chapter 8 Chapter Resource Menu Chapter Diagnostic Questions Formative Test Questions Chapter Assessment Questions Standardized Test Practice biologygmh.com Glencoe Biology Transparencies Image Bank Vocabulary Animation Click on a hyperlink to view the corresponding lesson.

45. Cellular Energy Chapter 8 Chapter Diagnostic Questions Which statement describes the law of conservation of energy? Energy cannot be converted or destroyed. Energy can be converted and destroyed. Energy can be converted but not destroyed. Energy can be destroyed but not converted.

46. Cellular Energy Chapter 8 Chapter Diagnostic Questions In which metabolic process are molecules broken down to produce carbon dioxide and water? photosynthesis cellular respiration homeostasis fermentation

47. Cellular Energy Chapter 8 Chapter Diagnostic Questions At the end of the Calvin cycle, where is energy stored? NADPH ATP chloroplast glucose

48. Cellular Energy Chapter 8 8.1 Formative Questions Which law of thermodynamics explains why the ladybug receives the least amount of usable energy?

49. Cellular Energy Chapter 8 8.1 Formative Questions the first law of thermodynamics the second law of thermodynamics

50. Cellular Energy Chapter 8 8.1 Formative Questions True or False All of the energy from the food you eat comes from the sun.