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PhotosynthesisPhotosynthesis

Energy & Life

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AutotrophsAutotrophs

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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AutotrophsAutotrophs

• 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

EuglenaEuglena

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HeterotrophsHeterotrophs• HeterotrophHeterotroph

s are s are organisms organisms that can NOT that can NOT make their make their own foodown food

• HeterotrophHeterotrophs can NOT s can NOT directly use directly use the sun’s the sun’s energyenergy

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EnergyEnergy• Energy Takes Many Energy Takes Many

Forms such as Forms such as light, light, heat, electrical, heat, electrical, chemical, mechanicalchemical, mechanical

• Energy can be Energy can be changed from changed from one one form to anotherform to another

• Energy can be stored Energy can be stored in chemical bonds & in chemical bonds & then released laterthen released later

Candles release energy as HEAT & LIGHTCandles release energy as HEAT & LIGHT

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ATP – Cellular EnergyATP – Cellular Energy• Adenosine TriphosphateAdenosine Triphosphate• Contains two, high-energy Contains two, high-energy

phosphate bondsphosphate bonds• Also contains the nitrogen base Also contains the nitrogen base

adenine & a ribose sugaradenine & a ribose sugar

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ADPADP• Adenosine DiphosphateAdenosine Diphosphate• ATP releases ATP releases energyenergy, a , a free free

phosphate,phosphate, & & ADPADP when cells when cells take energy from ATPtake energy from ATP

One phosphate bond has been removed

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Sugar in ADP & ATPSugar in ADP & ATP

•Called ribose

•Pentose sugar

•Also found on RNA

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Importance of ATPImportance of ATP

Principal Compound Used To Store Energy In Living Organisms

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Releasing Energy From Releasing Energy From ATPATP

• ATP is constantly being ATP is constantly being used used and remade by cellsand remade by cells

• ATP provides all of the ATP provides all of the energy for energy for cell activitiescell activities

• The high energy phosphate The high energy phosphate bonds can be bonds can be BROKENBROKEN to to release energyrelease energy

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Releasing Energy From Releasing Energy From ATPATP

• AddingAdding A A Phosphate Phosphate Group To ADP Group To ADP stores Energy in stores Energy in ATPATP

• RemovingRemoving A A Phosphate Phosphate Group From ATP Group From ATP Releases Energy Releases Energy & forms ADP& forms ADP

Lose

Gain

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Cells Using Biochemical Cells Using Biochemical EnergyEnergy

Cells Use ATP For:• Active transport• Movement• Photosynthesis• Protein Synthesis• Cellular

respiration• All other cellular

reactions

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More on ATPMore on ATP

• Cells Have Enough ATP Cells Have Enough ATP To Last For A To Last For A Few Few SecondsSeconds

• ATP must ATP must constantlyconstantly be be mademade

• ATP ATP Transfers Energy Transfers Energy Very WellVery Well

• ATP Is ATP Is NOTNOT Good At Good At Energy StorageEnergy Storage

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GlucoseGlucose

•Glucose is a Glucose is a monosaccharidemonosaccharide

•CC66HH1212OO66

•One Molecule of One Molecule of glucose Stores glucose Stores 90 90 TimesTimes More Chemical More Chemical Energy Than One Energy Than One Molecule of ATPMolecule of ATP

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History of History of Photosynthesis & Plant Photosynthesis & Plant

PigmentsPigments

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PhotosynthesisPhotosynthesis

• Is the process that captures Is the process that captures energy from the sunlight to energy from the sunlight to convert convert Water (HWater (H220)0) and and Carbon Dioxide (COCarbon Dioxide (CO22)) into into Oxygen (OOxygen (O22)) and and High High Energy CarbohydratesEnergy Carbohydrates (sugars, e.g. Glucose) & (sugars, e.g. Glucose) & StarchesStarches

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Investigating Investigating PhotosynthesisPhotosynthesis

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

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

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

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The Photosynthesis The Photosynthesis EquationEquation

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Inside A ChloroplastInside A Chloroplast

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Photosynthesis

•Plants absorb visible light for photosynthesis–Visible light appears white but is made up of several colors

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Light and PigmentsLight and Pigments• 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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Light

Color Wavelength

Red 625-740 nm (longest)

Orange 590-625 nmYellow 565-590 nmGreen 500-565 nmCyan 485-500 nmBlue 440-485 nmPurple 380-440 nm (shortest)

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PigmentsPigments

• 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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ChlorophyllChlorophyll

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

Chlorophyll aChlorophyll a

Chlorophyll bChlorophyll b

Magnesium atom at the center of chlorophyll

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Chlorophyll a and bChlorophyll a and b

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ChlorophyllChlorophyll

• Together, they absorb Together, they absorb mostly red and blue mostly red and blue wavelengthswavelengths

• They DO NOT absorb the They DO NOT absorb the green light (wavelength)green light (wavelength)

• The green is reflected, and The green is reflected, and this is why we see the this is why we see the green!green!

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Pigments

• Chloroplasts also have another type of pigments called accessory pigments– Appear red, orange, yellow, blue,

or scarlet when we see them

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Pigments

• Accessory Pigments– Carotenoids-oranges– Xanthophylls-yellows– Anthocyanins-scarlets/reds,

lavendars, purples, blues– Tannins-Brown

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The Colors of Autumn

• Complete the worksheets!

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Photosynthesis…

• occurs in CHLOROPLASTS of plants!

• Chloroplasts are located in leaf cells that are specialized for photosynthesis

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Photosynthesis…

• Photosynthesis has 2 main stages– Light-Dependent Reactions (require

light)—takes place in the thylakoids– Light-Independent Reactions—takes

place in the stroma

• The 2 main parts of chloroplast that are needed for Photosynthesis:– Thylakoids-stack to form a grana– Stroma-the fluid that surrounds the

grana inside the chloroplast

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Light-Dependent Reactions

• Capture energy from the sunlight

• Take place within and across the membrane of the thylakoids (that’s where the pigments are—whose job it is to capture light!)

• Water and sunlight are needed for this stage

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Light-Dependent Reactions

• Steps of Light-Dependent Reactions– 1. Chlorophyll absorbs energy

from sunlight. Water (H20) molecules are broken down. Oxygen (O2) molecules are released

– 2. Energy is transferred to molecules that carry energy (ATP & NADPH)

Light-Dependent Reactions in Detail• The light-dependent reactions include

groups of molecules called photosystems.

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Light Dependent Reactions in Detail

• Photosystem II captures and transfers energy.– chlorophyll absorbs

energy from sunlight– energized electrons

enter electron transport chain– water molecules are split– oxygen is released as waste– hydrogen ions are transported

across thylakoid membrane (from low to high)

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Light Dependent Reactions in Detail

• Photosystem I captures energy and produces energy-carrying molecules.– chlorophyll absorbs

energy from sunlight– energized electrons are

used to make NADPH– NADPH is transferred to

light-independent reactions

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Light Dependent Reactions in Detail• The light-dependent reactions produce

ATP.– hydrogen ions flow through a channel

in the thylakoid membrane– ATP synthase attached to the channel

makes ATP

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Light-Independent Reactions

•Uses energy from the light-dependent rxn to make sugar

•Occur in the stroma •Carbon dioxide

molecules are needed for this stage

Light-Independent Reactions

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The second stage of photosynthesis uses energy from the first stage to make sugars.

Calvin Cycle

Dark Reactions

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Steps of Light-Independent Reaction

• 1. Carbon Dioxide is added to build larger molecules

• 2. A molecule of a simple sugar is formed– Usually glucose (C6H12O6)

• Stores some of the energy that was captured from the sunlight

Light Independent Reactions (Calvin Cycle) in Detail• A molecule of glucose is formed as

it stores some of the energy captured from sunlight.– carbon dioxide molecules enter

the Calvin cycle– energy is added and carbon

molecules are rearranged– a high-energy three-carbon

molecule leaves the cycle

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Light Independent Reactions (Calvin Cycle) in Detail

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Light Independent Reactions (Calvin Cycle) in Detail• A molecule of glucose is formed as

it stores some of the energy captured from sunlight.– two three-carbon molecules bond

to form a sugar– remaining molecules stay in the

cycle

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Photosynthesis Photosynthesis OverviewOverview

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Factors Affecting the Factors Affecting the Rate of PhotosynthesisRate of Photosynthesis

• Amount of Amount of available available waterwater

• TemperatureTemperature• Amount of Amount of

available available light energylight energy