CHAPTER 9: SECTION ONE

1. CHAPTER 9: SECTION ONE PHOTOSYNTHESIS & CELLULAR RESPIRATION

2. ENERGY IN LIVING THINGS • What type of energy is used in cells, and what is the ultimate source of this energy? • How is an organism’s metabolism related to the carbon cycle? • How is energy released in a cell?

3. What type of energy is used in cells, and what is the ultimate source of this energy? CHEMICAL ENERGY Our ultimate source of NRG!! • Organisms use and store energy in the chemical bonds of organic compounds. Almost all of the energy in organic compounds comes from the sun. • Organisms require a constant source of energy.

4. HOMEOSTASIS • Energy is needed for organisms to maintain their homeostasis. • Homeostasis is the process of maintaining internal order and balance even when the environment changes.

5. PHOTOSYNTHESIS • Photosynthesis is the process by which plants, algae, and some bacteria use sunlight, carbon dioxide, and water to produce carbohydrates and oxygen. • Organisms that are able to perform photosynthesis, such as plants, are autotrophs.

6. AUTOTROPHS Serve as food for almost all other organisms on Earth. Autotrophs • Autotrophs make organic compounds that serve as food for them and for almost all of the other organisms on Earth. • Organisms that cannot make their own food must absorb food molecules made by autotrophs, eat autotrophs, or eat organisms that consume autotrophs. • Food molecules that are made or consumed by an organism are the fuel for its cells.

7. ENERGY FOR LIFE PROCESSES FUEL FOR THE CELLS!! FOOD • Food molecules that are made or consumed by an organism are the fuel for its cells. • Cells use these molecules to release the energy stored in the molecules’ bonds. The energy is used to carry out life processes.

8. METABOLISM & THE CARBON CYCLE………… How is an organism’s metabolism related to the carbon cycle?

9. How is an organism’s metabolism related to the carbon cycle? METABOLISM Organisms’ metabolism is part of Earth’s carbon cycle. • Metabolism involves either using energy to build organic molecules or breaking down organic molecules in which energy is stored. • Organic molecules contain carbon. Therefore, an organism’s metabolism is part of Earth’s carbon cycle.

10. CELLULAR RESPIRATION & PHOTOSYNTHESIS PHOTOSYNTHESIS CELLULAR RESPIRATION • Energy enters an ecosystem when organisms use sunlight during photosynthesis to convert carbon dioxide molecules into glucose. • Through the process of cellular respiration, cells make the carbon in glucose into stable carbon dioxide molecules and produce energy.

11. Adenosine triphosphate Cell’s Energy Currency ATP • Energy is also released and used to make ATP (adenosine triphospate), an organic molecule that is the main energy source for cell processes.

12. TRANSFERRING ENERGY HOW IS ENERGY RELEASED IN A CELL?

13. Enzymes are proteins that act as catalysts in biochemical reactions. ENZYMES CATALYSTS • In cells, chemical energy is gradually released in a series of chemical reactions that are assisted by enzymes. • In chemical reactions, energy can be absorbed and released during the breaking and forming of bonds.

14. ATP • When cells break down food molecules, some of the energy in the molecules is released as heat. Much of the remaining energy is used to make ATP. • ATP is a portable form of energy “currency” inside cells.

15. So like, what is atp exactly??? • ATP is a nucleotide made up of a chain of three phosphate groups. When the bond of the third phosphate group is broken, energy is released, producing ADP.

16. ATP SYNTHASE • In many cells, ATP synthase, an enzyme that catalyzes the synthesis of ATP, recycles ADP by bonding a third phosphate group to the molecule. • ATP synthase acts as both an enzyme and a carrier protein for hydrogen ions. • The flow of H+ ions through ATP synthase powers the production of ATP.

17. Hydrogen ion pumps HYDROGEN IONS NADH & NADPH…..HUH?? • In chloroplasts and mitochondria, a series of molecules, called an electron transport chain, pump H+ ions across the membrane to create a concentration gradient. • The electron transport chain uses energy from released electron carriers, such as NADH and NADPH, to pump hydrogen ions.

18. PHOTOSYNTHESIS CHAPTER 9: SECTION TWO

19. KEY QUESTIONS???? • What is the role of pigments in photosynthesis? • What are the roles of the electron transport chains? • How do plants make sugars and store extra unused energy? • What are the three environmental factors that affect photosynthesis?

20. What is the role of pigments in photosynthesis? In plants, light energy is harvested by pigments that are located in the thylakoid membrane of chloroplasts. Photosynthesis is the process that provides energy for almost all life. Chloroplasts are the organelles that convert light energy into chemical energy.

21. Within the inner membrane of the chloroplast, is the stroma which contains the thylakoid membrane. • – This membrane produces flat, disc-like sacs called thylakoids that are arranged in stacks and contain molecules that absorb light energy for photosynthesis.

22. Light is a form of electromagnetic radiation, energy that can travel through empty space in the form of waves. • – Sunlight contains all of the wavelengths of visible light which we see as different colors.

23. A pigment is a substance that absorbs certain wavelengths (colors) of light and reflects all of the others. • – Chlorophyll is a green pigment in chloroplasts that absorbs light energy to start photosynthesis. It absorbs mostly blue and red light and reflects green and yellow light, which makes plants appear green.

24. Plants also have pigments called carotenoids which help plants absorb additional light energy. • When light hits a thylakoid, energy is absorbed by many pigment molecules and eventually transferred to electron carriers.

25. ELECTRON TRANSPORT CHAIN What are the roles of the electron transport chains?

26. During photosynthesis, one electron transport chain provides energy to make ATP, while the other provides energy to make NADPH. • • Both chains use energy from electrons excited by light.

27. Producing ATP and NADPH • Step 1: Electrons excited by light leave the chlorophyll molecules. An enzyme splits water molecules to replace these electrons. Oxygen gas is formed and released into the atmosphere.

28. Step 2: Excited electrons transfer some of their energy to pump H+ ions into the thylakoid. This process creates a concentration gradient across the thylakoid membrane.

29. Step 3: The energy from diffusion of H+ ions through the channel portion of ATP synthase is used to catalyze a reaction in which a phosphate group is added to a molecule of ADP, producing ATP. • –

30. Step 4: Light excites electrons in another chlorophyll molecule. The electrons are passed on to the second chain and replaced by the de-energized electrons from the first chain. Step 5: Excited electrons combine with H+ ions and NADP+ to form NADPH NADPH is an electron carrier that provides high-energy electrons needed to store energy in organic molecules.

31. PRODUCING SUGARS How do plants make sugars and store extra unused energy?

32. In the final stage of photosynthesis, ATP and NADPH are used to produce energy-storing sugar molecules from the carbon in carbon dioxide. • The first two stages of photosynthesis depend directly on light because light energy is used to make ATP and NADPH. • • The use of carbon dioxide to make organic compounds is called carbon dioxide fixation, or carbon fixation.

33. The reactions that fix carbon dioxide are light-independent reactions, sometimes called dark reactions. • • The most common method of carbon fixation is the Calvin cycle. • • Atmospheric carbon dioxide is combined with other carbon compounds to produce organic compounds. ATP and NADPH supply some of the energy required in these reactions.

34. FACTORS THAT AFFECT PHOTOSYNTHESIS What are the three environmental factors that affect photosynthesis?

35. Light intensity, carbon dioxide concentration, and temperature are three environmental factors that affect photosynthesis.

36. In general, the rate of photosynthesis increases as light intensity increases until all of the pigments in a chloroplast are being used. • • The concentration of carbon dioxide affects the rate of photosynthesis in a way similar to light. • • Photosynthesis is most efficient in a certain range of temperatures.