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The Working Cell: Energy from Sunlight. Chapter 8 Notes. Ch. 8 The Working Cell: Energy from Light. 8.1 Photosynthesis uses light energy to make food. 8.2 The light reactions convert light energy to chemical energy. 8.3 The Calvin cycle makes sugar from carbon dioxide.
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The Working Cell:Energy from Sunlight Chapter 8 Notes
Ch. 8 The Working Cell: Energy from Light 8.1 Photosynthesis uses light energy to make food. 8.2 The light reactions convert light energy to chemical energy. 8.3 The Calvin cycle makes sugar from carbon dioxide. 8.4 Photosynthesis has a global impact.
8.1 Photosynthesis uses light energy to make food. • Objectives • Describe the structure of a chloroplast. • Identify the overall reactants and products of photosynthesis.
8.1 Photosynthesis uses light energy to make food. • Key Terms • Chloroplast • Chlorophyll • Stroma • Thylakoid • Light reactions • Calvin cycle
8.1 Photosynthesis uses light energy to make food. • Photosynthesis is the process by which plants & other producers convert energy of sunlight to energy stored in organic molecules. • Chloroplast – organelle where photosynthesis takes place • Chlorophyll – chemical that gives a green color to chloroplasts.
8.1 Photosynthesis uses light energy to make food. • Chloroplasts structure is key to its function • Has an inner & outer membrane • Inner membrane encloses a thick fluid called the stroma • Suspended in the stroma are thylakoids – disk-shaped sacs
8.1 Photosynthesis uses light energy to make food. • Cellular respiration – fall of electrons form glucose to oxygen gives off energy, which is then used to make ATP. • Photosynthesis is the opposite – electrons from water are boosted uphill by the energy from sunlight.
8.1 Photosynthesis uses light energy to make food. • Excited electrons along with carbon dioxide & water are used by chloroplasts to produce glucose & oxygen.
8.1 Photosynthesis uses light energy to make food. • Photosynthesis occurs in 2 main stages. • Light reactions – convert sunlight to chemical energy • Stored in NADPH & ATP • Calvin cycle – makes sugar from carbon dioxide and H+ ions from the splitting of water.
8.1 Concept check (QUIZ) • Draw & label a simple diagram of a chloroplast that includes the following structures: outer & inner membranes, stroma, thylakoids. • What are the reactants of photosynthesis, what are the products? • Name the 2 main stages of photosynthesis. How are they related?
8.2 The light reactions convert light energy to chemical energy • Objectives • Explain how light interacts with pigments. • Describe how photosystems help harvest light energy. • Identify the chemical products of the light reactions.
8.2 The light reactions convert light energy to chemical energy • Key Terms • Wavelength • Electromagnetic spectrum • Pigment • Paper chromatography • photosystem
8.2 The light reactions convert light energy to chemical energy • Light energy is a form of electromagnetic energy • Travels in waves (similar to ocean waves) • Measured by wavelength – distance between 2 adjacent waves.
8.2 The light reactions convert light energy to chemical energy • Different forms of electromagnetic energy have characteristic wavelengths • Electromagnetic spectrum – the range of types of electromagnetic energy
8.2 The light reactions convert light energy to chemical energy • Pigments – chemical compounds that give a substance its color. • Cause different wavelengths to be… • Absorbed • Transmitted • Reflected
8.2 The light reactions convert light energy to chemical energy • Paper chromatography – lab technique used to observe different pigments in substances.
8.2 The light reactions convert light energy to chemical energy • Harvesting light energy • Photosystems – clusters of pigment molecules • Chlorophyll a • Chlorophyll b • Carotenoids
8.2 The light reactions convert light energy to chemical energy • Harvesting light energy • 1)Pigments absorb light energy • 2)transfer energy to electrons • 3)transfer energy to electronacceptor. • 4)converts to ATP or NADPH.
8.2 The light reactions convert light energy to chemical energy • Chemical products of the light reactions • Oxygen, released as a waste product of the 1st photosystem. • ATP – produced by the release of energy by the electron transport chain between photosystems. • NADPH – produced by the second photosystem
8.2 Concept check • Explain why a leaf appears green. • Describe what happens when a molecule of chlorophyll a absorbs light. • Besides oxygen, what 2 molecules are produced by the light reactions? • Where in the chloroplast do the light reactions take place?
8.3 The Calvin cycle makes sugar from carbon dioxide • Objectives • Explain how the Calvin cycle makes sugar. • Summarize the overall process of photosynthesis.
8.3 The Calvin cycle makes sugar from carbon dioxide • The Calvin cycle • Called a cycle because the starting material RuBP is regenerated each time the process occurs • RuBP is a 5 carbon sugar
From air From light reactions 8.3 The Calvin cycle makes sugar from carbon dioxide • Into the Calvin cycle • Carbon dioxide • ATP • NADPH
8.3 The Calvin cycle makes sugar from carbon dioxide • Outputs of Calvin cycle • G3P (an energy rich sugar) • Not yet glucose • Used by plant to make glucose • ADP + P • NADP+
8.3 The Calvin cycle makes sugar from carbon dioxide • Summary of photosynthesis • Light reactions • Convert light energy to chemical energy • Occurs in thylakoids • Uses water (reactant) & releases oxygen (product)
8.3 The Calvin cycle makes sugar from carbon dioxide • Calvin cycle • Occurs in stroma • Uses ATP & NADPH • Converts carbon dioxide (reactant) to sugar (product)
8.3 Concept check • What are the inputs & outputs of the Calvin cycle? • Which stage of photosynthesis uses each reactant from the overall photosynthesis equation? Which stage generates each product from the overall photosynthesis equation?
8.3 Concept check • Why is the Calvin cycle called a cycle? • What molecule is the direct product of photosynthesis? How is that molecule then used by the plant cell?
8.4 Photosynthesis has a global impact. • Objectives • Describe the path of carbon in the carbon cycle. • Explain how photosynthesis is related to climate.
8.4 Photosynthesis has a global impact. • Key Terms • Carbon cycle • Greenhouse effect
8.4 Photosynthesis has a global impact. • Processes that occur on a global scale depend on chloroplasts & mitochondrion • Carbon cycle – process by which carbon moves from inorganic to organic & back to inorganic.
8.4 Photosynthesis has a global impact. • Path of carbon in the carbon cycle • Producers convert inorganic carbon to organic carbon through photosynthesis. • Consumers eat the producers, may be eaten by other consumers. • Cellular respiration by both producers & consumers eventually carbon dioxide to the atmosphere
8.4 Photosynthesis has a global impact. • Plants & other photosynthetic organisms make about 160 billion metric tons of organic material. • 80 trillion copies of book • 25 stacks reaching to the sun.
8.4 Photosynthesis has a global impact. • Carbon dioxide in the atmosphere traps in heat – greenhouse effect • Keeps world climate warm enough for living things. • Average 10°C warmer than it would be. • Amount of carbon dioxide in atmosphere is rising.
