Energy & Life 1. 2 Plants and some other types of organisms that contain chlorophyll are able to use light energy from the sun to produce food. 3.

Energy & Life

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Plants and Plants and some other some other types of types of organisms that organisms that contain contain chlorophyllchlorophyll are are able to use able to use light energy light energy from the sunfrom the sun to produce to produce food.food.

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Autotrophs Autotrophs include include organismsorganisms that make that make their own foodtheir own food

Autotrophs Autotrophs can use the can use the sun’s energy sun’s energy directlydirectly

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EuglenaEuglena

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Involves the Use Of light Involves the Use Of light Energy to convert Energy to convert Water Water (H(H220)0) and and Carbon Dioxide Carbon Dioxide (CO(CO22)) into into Oxygen (OOxygen (O22)) and and High Energy CarbohydratesHigh Energy Carbohydrates (sugars, e.g. Glucose) & (sugars, e.g. Glucose) & StarchesStarches

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•Many Scientists Have Many Scientists Have Contributed To Contributed To Understanding Understanding PhotosynthesisPhotosynthesis

•Early ResearchEarly Research Focused Focused On The On The Overall ProcessOverall Process

•Later ResearchersLater Researchers Investigated The Detailed Investigated The Detailed Chemical PathwaysChemical Pathways

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First to trace the path First to trace the path that that carbon (COcarbon (CO22)) takes in forming takes in forming GlucoseGlucoseDoes Does NOTNOT require require sunlightsunlightCalled the Called the Calvin CycleCalvin Cycle or or Light Independent Light Independent ReactionReactionAlso knownAlso known as the as the Dark ReactionDark Reaction

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•In addition to water, carbon dioxide, and light energy, photosynthesis requires Pigments

•Chlorophyll is the primary light-absorbing pigment in autotrophs

•Chlorophyll is found inside chloroplasts

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Energy From The Sun Enters Earth’s Biosphere As Photons

Photon = Light Energy Unit

Light Contains A Mixture Of Wavelengths

Different Wavelengths Have Different Colors

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Different pigmentsDifferent pigments absorb absorb different different wavelengthswavelengths of light of light

Photons of light Photons of light “excite”“excite” electrons in the plant’s electrons in the plant’s pigmentspigments

Excited electrons carry the Excited electrons carry the absorbed energyabsorbed energy

Excited electrons move to Excited electrons move to HIGHERHIGHER energy levels energy levels

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There are 2 main types of There are 2 main types of chlorophyll molecules:chlorophyll molecules:

Chlorophyll a Chlorophyll a found in all found in all plants, algae, & plants, algae, & cyanobacteriacyanobacteria

Chlorophyll b Chlorophyll b is an accessory is an accessory pigment. Transfer the pigment. Transfer the light it absorbed to light it absorbed to chlorophyll achlorophyll a

A third type, A third type, chlorophyll cchlorophyll c, is , is found in dinoflagellates, found in dinoflagellates, brown algae and diatoms.brown algae and diatoms.

Green light is reflected from Green light is reflected from the chlorophyll giving the the chlorophyll giving the plants its green color.plants its green color.

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Double Double membranemembrane organelleorganelle

Outer membrane Outer membrane smoothsmooth

Inner membraneInner membrane forms stacks of forms stacks of connected sacs connected sacs called called thylakoidsthylakoids

Thylakoid stack Thylakoid stack is called the is called the granungranun (grana- (grana-plural)plural)

Gel-like material Gel-like material around grana around grana called called stromastroma

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Light Light IndependentIndependent reactions reactions occur hereoccur here

ATP usedATP used to to make make carbohydrates carbohydrates like like glucoseglucose

Location of the Location of the Calvin CycleCalvin Cycle

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Light Light DependentDependent reactions occur reactions occur herehere

Photosystems Photosystems are made up of are made up of clusters of clusters of chlorophyll chlorophyll moleculesmolecules

Photosystems Photosystems are are embedded embedded in the thylakoid in the thylakoid membranesmembranes

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Nicotinamide Adenine Nicotinamide Adenine Dinucleotide Phosphate Dinucleotide Phosphate (NADP(NADP++))

NADPNADP+ = + = ReducedReduced Form Form Picks Up Picks Up 2 high-energy 2 high-energy electrons and Helectrons and H++ from the from the Light Reaction to form NADPHLight Reaction to form NADPH

NADPHNADPH carries energy to be carries energy to be passed on to another moleculepassed on to another molecule

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Occurs across the Occurs across the thylakoid membranesthylakoid membranes

Uses light energyUses light energy Produce Produce OxygenOxygen from from waterwater

Convert Convert ADP to ATPADP to ATP Also convert Also convert NADPNADP++ into into the energy carrier the energy carrier NADPHNADPH

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Photosystem Photosystem absorbs light absorbs light energyenergy

Electrons are Electrons are energizedenergized and and passed to the passed to the Electron Electron Transport ChainTransport Chain

Lost electrons are Lost electrons are replaced from the replaced from the splitting of watersplitting of water into 2Hinto 2H+, +, free free electrons, and electrons, and OxygenOxygen

2H2H+ + pumped across pumped across thylakoid thylakoid membranemembrane

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High-energy electronsHigh-energy electrons are are moved to Photosystem I moved to Photosystem I through the Electron through the Electron Transport ChainTransport Chain

Energy is used to Energy is used to transport transport HH++ from stroma to inner from stroma to inner thylakoid membranethylakoid membrane

NADP+ converted to NADP+ converted to NADPHNADPH when it picks up 2 when it picks up 2 electrons & H+electrons & H+

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Enzyme in thylakoid Enzyme in thylakoid membrane called membrane called ATP ATP SynthaseSynthase

As H+ ions passed As H+ ions passed through thylakoid through thylakoid membrane, membrane, enzyme enzyme binds them to ADPbinds them to ADP

Forms Forms ATPATP for cellular for cellular

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Reactants:Reactants: HH22OO Light EnergyLight Energy

Energy Products:Energy Products: ATPATP NADPHNADPH

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ATP & NADPHATP & NADPH from light from light reactions used as energyreactions used as energy

Atmospheric Atmospheric C0C022 is used is used to to make sugarsmake sugars like like glucose and fructoseglucose and fructose

Six-carbon Sugars made Six-carbon Sugars made during the during the Calvin CycleCalvin Cycle

Occurs in theOccurs in the stroma stroma27

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It takes two turns in the calvin cycle to create to create 1 carbohydrate.

The carbohydrate is a glucose sugar molecule.

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Light Independent Reaction Light Independent Reaction SummarySummary

Reactants:Reactants: Energy molecules Energy molecules used are ATP and used are ATP and NadphNadph

COCO22Carbon Fixation Carbon Fixation

Products:Products: Glucose

Amount of Amount of available available waterwater

TemperatureTemperature Amount of Amount of available light available light energyenergy

Color of LightColor of Light30