the working cell: energy from sunlight chapter 8 notes
TRANSCRIPT
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 sugarfrom 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.
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 Photosynthesis uses light energy to make food.
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.
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 energyTravels 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…
AbsorbedTransmittedReflected
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 energy1)Pigments absorb light energy2)transfer energy to electrons3)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 The light reactions convert light energy to chemical energy
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.
The Calvin cycleCalled a cycle because the starting
material RuBP is regenerated each time the process occursRuBP is a 5 carbon sugar
8.3 The Calvin cycle makes sugar from carbon dioxide
Into the Calvin cycleCarbon dioxideATPNADPH
8.3 The Calvin cycle makes sugar from carbon dioxide
From air
From light reactions
Outputs of Calvin cycleG3P (an energy rich sugar)
–Not yet glucose
–Used by plant to make glucoseADP + PNADP+
8.3 The Calvin cycle makes sugar from carbon dioxide
Summary of photosynthesisLight reactions
Convert light energy to chemical energy
Occurs in thylakoidsUses water (reactant) & releases
oxygen (product)
8.3 The Calvin cycle makes sugar from carbon dioxide
Calvin cycleOccurs in stromaUses ATP & NADPHConverts carbon dioxide (reactant)
to sugar (product)
8.3 The Calvin cycle makes sugar from carbon dioxide
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?
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?
8.3 Concept check
8.4 Photosynthesis has a global impact. Objectives
Describe the path of carbon in the carbon cycle.
Explain how photosynthesis is related to climate.
Key TermsCarbon cycleGreenhouse effect
8.4 Photosynthesis has a global impact.
Processes that occur on a global scale depend on chloroplasts & mitochondrionCarbon 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
1) Producers convert inorganic carbon to organic carbon through photosynthesis.
2) Consumers eat the producers, may be eaten by other consumers.
3) 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 book25 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.
8.4 Photosynthesis has a global impact.
Photosynthesis
Stages of Photosynthesis
Electromagnetic spectrum
Pigments & Color
Harvesting Light Energy
Chemical products of light reactions
Calvin cycle
Photosynthesis
Greenhouse effect
Light Waves