Photosynthesis Energy & Life copyright cmassengale 1

PhotosynthesiPhotosynthesiss

Energy & Lifecopyright cmassengale1

Overview of Overview of PhotosynthesisPhotosynthesis

copyright cmassengale2

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.


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

HeterotrophsHeterotrophs• Heterotrophs Heterotrophs

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

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


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

copyright cmassengale6Candles release energy as HEAT & LIGHTCandles release energy as HEAT & LIGHT

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


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

copyright cmassengale8One phosphate bond has been

removed

Sugar in ADP & ATPSugar in ADP & ATP

• Called ribose

• Pentose sugar

• Also found on RNA


Importance of ATPImportance of ATP

Principal Compound Used To Store Energy In Living Organisms


Releasing Energy From Releasing Energy From ATPATP

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

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

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

• The process of releasing ATP’s The process of releasing ATP’s energy & reforming the molecule energy & reforming the molecule is called is called phosphorylationphosphorylation


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


Loose

Gain

Cells Using Biochemical Cells Using Biochemical EnergyEnergy

Cells Use ATP For:

• Active transport

• Movement

• Photosynthesis

• Protein Synthesis

• Cellular respiration

• All other cellular reactions


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


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


History of History of Photosynthesis & Photosynthesis & Plant PigmentsPlant Pigments


PhotosynthesisPhotosynthesis

• 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


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


Early Questions on Early Questions on PlantsPlants

Several Centuries Ago, Several Centuries Ago, The Question Was:The Question Was:

Does the increase in Does the increase in mass of a plant come mass of a plant come from the air? The soil? from the air? The soil?

The Water?The Water?


Van Helmont’s Van Helmont’s Experiment 1643Experiment 1643

• Planted a Planted a seedseed into into A pre-measured A pre-measured amount of soil and amount of soil and wateredwatered for 5 years for 5 years

• Weighed Plant & Weighed Plant & Soil.Soil. Plant Was 75 Plant Was 75 kg, Soil The Same.kg, Soil The Same.

• Concluded Mass Concluded Mass Came From WaterCame From Water


Priestley’s Experiment Priestley’s Experiment 17711771

• Burned Candle In Bell Jar Until It Went Out.

• Placed Sprig Of Mint In Bell Jar For A Few Days.

• Candle Could Be Relit And Burn.

• Concluded Plants Released Substance (O2) Necessary For burning.


Ingenhousz’s Ingenhousz’s Experiment 1779Experiment 1779

copyright cmassengale22Repeated Priestly experiment with & without Repeated Priestly experiment with & without

sunlightsunlight

Results of Ingenhousz’s Results of Ingenhousz’s ExperimentExperiment

• Showed That Priestley’s Showed That Priestley’s Results Only Occurred In Results Only Occurred In The Presence Of The Presence Of SunlightSunlight..

• Light Was Necessary For Light Was Necessary For Plants To Produce The Plants To Produce The “Burning Gas” or “Burning Gas” or oxygenoxygen


Julius Robert Mayer Julius Robert Mayer 18451845

Proposed That Proposed That Plants can Plants can Convert Convert Light Light Energy Into Energy Into ChemicalChemical EnergyEnergy


Samuel Ruben & Martin Samuel Ruben & Martin KamenKamen19411941

Used Isotopes Used Isotopes To Determine To Determine That The That The OxygenOxygen Liberated In Liberated In PhotosynthePhotosynthesis sis Comes Comes From WaterFrom Water

copyright cmassengale25KAMENKAMEN

RUBINRUBIN

Melvin Calvin 1948Melvin Calvin 1948•First to trace the path First to trace the path that that carbon (COcarbon (CO22)) takes in forming takes in forming GlucoseGlucose

•Does Does NOTNOT require require sunlightsunlight•Called the Called the Calvin CycleCalvin Cycle or or Light Independent Light Independent ReactionReaction

•Also knownAlso known as the as the Dark ReactionDark Reaction


Rudolph Marcus 1992Rudolph Marcus 1992•Studied the Studied the Light Light Independent Independent ReactionsReactions

•First to First to describe the describe the Electron Electron transport transport ChainChain


The Photosynthesis The Photosynthesis EquationEquation


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


Light and Light and PigmentsPigments

• 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


Light & PigmentsLight & Pigments• 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


ChlorophyllChlorophyllThere are 2 main There are 2 main

types of chlorophyll types of chlorophyll molecules:molecules:

Chlorophyll aChlorophyll a

Chlorophyll bChlorophyll b

A third type, A third type, chlorophyll chlorophyll cc, is found in , is found in dinoflagellatesdinoflagellates


Magnesium atom at the center of chlorophyll

Chlorophyll a and bChlorophyll a and b


Chlorophyll aChlorophyll a

•Found in all Found in all plants, algae, & plants, algae, & cyanobacteriacyanobacteria

•Makes photosynthesis Makes photosynthesis possiblepossible

•Participates Participates directlydirectly in the in the Light ReactionsLight Reactions

•Can Can accept energyaccept energy from from chlorophyll bchlorophyll b


Chlorophyll bChlorophyll b

• Chlorophyll b is an Chlorophyll b is an accessory pigmentaccessory pigment

• Chlorophyll b acts Chlorophyll b acts indirectlyindirectly in photosynthesis by in photosynthesis by transferring the light it transferring the light it absorbs to chlorophyll absorbs to chlorophyll aa

• Like chlorophyll a, it Like chlorophyll a, it absorbs red & blue light absorbs red & blue light and and REFLECTS GREENREFLECTS GREEN


The Biochemical The Biochemical ReactionsReactions


It Begins with It Begins with Sunlight!Sunlight!


Photoautotrophs Absorb Photoautotrophs Absorb Light EnergyLight Energy


Inside A ChloroplastInside A Chloroplast


Structure of the Structure of the ChloroplastChloroplast

• Double membraneDouble membrane organelle organelle• Outer membrane Outer membrane smoothsmooth• Inner membraneInner membrane forms stacks forms stacks

of connected sacs called of connected sacs called thylakoidsthylakoids

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

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


Function of the Function of the StromaStroma

• Light IndependentLight Independent reactions occur herereactions occur here

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

• Location of the Location of the Calvin Calvin CycleCycle



Thylakoid membranesThylakoid membranes• Light DependentLight Dependent reactions reactions

occur hereoccur here• Photosystems are made up Photosystems are made up

of of clusters of chlorophyll clusters of chlorophyll moleculesmolecules

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

• The two photosystems are:The two photosystems are:

Photosytem IPhotosytem I

Photosystem IIPhotosystem II copyright cmassengale43

Photosynthesis Photosynthesis OverviewOverview


Energy CarriersEnergy Carriers• 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


NADPHNADPH


Light Dependent Light Dependent ReactionsReactions

• Occurs across the Occurs across the thylakoid thylakoid membranesmembranes

• Uses light energyUses light energy

• Produce Produce OxygenOxygen from water from water

• Convert Convert ADP to ATPADP to ATP

• Also convert Also convert NADPNADP++ into into the energy carrier the energy carrier NADPHNADPH


Light Dependent Light Dependent ReactionReaction


Light Dependent Light Dependent ReactionReaction


Light Reaction Light Reaction SummarySummary

Reactants:Reactants:

• HH22OO

• Light EnergyLight Energy

Energy Products:Energy Products:

• ATPATP

• NADPHNADPHcopyright cmassengale50

Light Independent Light Independent ReactionReaction

• 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 glucose and like glucose and fructosefructose

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

• Occurs in theOccurs in the stroma stromacopyright cmassengale51

The Calvin CycleThe Calvin Cycle


The Calvin CycleThe Calvin Cycle

• Two turnsTwo turns of the Calvin Cycle are of the Calvin Cycle are required to make one molecule of required to make one molecule of glucoseglucose

• 3-CO3-CO22 molecules enter the cycle molecules enter the cycle to form several to form several intermediate intermediate compounds (PGA)compounds (PGA)

• A 3-carbon molecule called A 3-carbon molecule called Ribulose BiphosphateRibulose Biphosphate (RuBP) is (RuBP) is used to regenerate the Calvin used to regenerate the Calvin cyclecycle



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


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Photosynthesis Energy & Life copyright cmassengale 1