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PhotosynthesiPhotosynthesiss

Energy & Life

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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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HeterotrophsHeterotrophsHeterotrophs Heterotrophs are organisms are organisms that can NOT that can NOT make their make their own foodown foodHeterotrophs Heterotrophs can NOT can NOT directly use directly use the sun’s the sun’s energyenergy

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ATP – Cellular EnergyATP – Cellular EnergyAdenosine TriphosphateAdenosine Triphosphate

Contains Contains twotwo, high-energy , 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 in 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 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

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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

Loose

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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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

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The Photosynthesis The Photosynthesis EquationEquation

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ChlorophyllChlorophyllThere 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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Inside A ChloroplastInside A Chloroplast

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Structure of the Structure of the ChloroplastChloroplast

•Double membraneDouble membrane organelleorganelle

•Outer membrane Outer membrane smoothsmooth• Inner membraneInner membrane forms forms

stacks of connected sacs stacks of connected sacs called called thylakoidsthylakoids

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

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

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Function of the StromaFunction of the Stroma

•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

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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 embedded in the thylakoid membranesin the thylakoid membranes

• The two photosystems are:The two photosystems are: Photosytem IPhotosytem I Photosystem IIPhotosystem II

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Photosynthesis Photosynthesis OverviewOverview

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Energy CarriersEnergy Carriers• Nicotinamide Adenine Dinucleotide Nicotinamide Adenine Dinucleotide

Phosphate Phosphate (NADP(NADP++))

•NADPNADP+ = + = ReducedReduced Form Form•Picks Up Picks Up 2 high-energy 2 high-energy

electrons and Helectrons and H++ from the Light from the Light Reaction to form NADPHReaction 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 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 ReactionsReactions

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Light Dependent Light Dependent ReactionReaction

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Light Dependent Light Dependent ReactionReaction

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Photosystem IPhotosystem I

•Discovered Discovered FirstFirst•Active in the final stage Active in the final stage of the Light Dependent of the Light Dependent ReactionReaction•Made of 300 molecules Made of 300 molecules of Chlorophyllof Chlorophyll•Almost completely Almost completely chlorophyll achlorophyll a

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Photosystem IIPhotosystem II

•Discovered Discovered SecondSecond•Active in the beginning Active in the beginning stage Of the Light stage Of the Light Dependent ReactionDependent Reaction•Contains about Contains about equal equal amounts of chlorophyll a amounts of chlorophyll a and chlorophyll band chlorophyll b

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Photosynthesis BeginsPhotosynthesis Begins

Photosystem Photosystem II absorbs light energyII absorbs light energy

Electrons are energizedElectrons are energized and passed and passed to the to the Electron Transport ChainElectron Transport Chain

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

2H2H+ + pumped across thylakoid pumped across thylakoid membranemembrane

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Photosystem IPhotosystem I

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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PhosphorylationPhosphorylation

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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Light Reaction SummaryLight Reaction Summary

Reactants:Reactants:

•HH22OO

• Light EnergyLight Energy

Energy Products:Energy Products:•ATPATP•NADPHNADPH

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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 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 stroma

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The Calvin CycleThe Calvin Cycle

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The Calvin CycleThe Calvin Cycle• Two turnsTwo turns of the Calvin Cycle of the Calvin Cycle

are required to make one are required to make one molecule of glucosemolecule of glucose

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

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

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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