Photosynthesis Energy & Life. Overview of Photosynthesis

PhotosynthesisPhotosynthesis

Energy & Life

Overview of Overview of PhotosynthesisPhotosynthesis

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

AutotrophsAutotrophs

•Autotrophs Autotrophs include include organismsorganisms that that make their own make their own foodfood

•Autotrophs can Autotrophs can use the sun’s use the sun’s energy directlyenergy directly

EuglenaEuglena

HeterotrophsHeterotrophs

•Heterotrophs Heterotrophs are organisms are organisms that can NOT that can NOT make their own make their own foodfood

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

EnergyEnergy

• Energy can be changed Energy can be changed from from one form to one form to anotheranother

• 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

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

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

base adenine & a ribose base adenine & a ribose sugarsugar

ADPADP•Adenosine DiphosphateAdenosine Diphosphate•ATP releases ATP releases energyenergy, a , a free phosphate,free phosphate, & & ADPADP when cells take energy when cells take energy from ATPfrom ATP

One phosphate bond has been removed

Importance of ATPImportance of ATP

Principal Compound Used To Store Energy In Living Organisms. Most energy stored between the last 2 phosphate bonds

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 energyrelease energy

Releasing Energy From Releasing Energy From ATPATP

• AddingAdding A A Phosphate Group Phosphate Group To ADP stores To ADP stores Energy in ATPEnergy in ATP

• RemovingRemoving A A Phosphate Group Phosphate Group From ATP 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

GlucoseGlucose•Glucose is a Glucose is a monosaccharidemonosaccharide

•CC66HH1212OO66

•One Molecule of glucose One Molecule of glucose Stores Stores 90 Times90 Times More More Chemical Energy Than One Chemical Energy Than One Molecule of ATPMolecule of ATP

History of History of Photosynthesis & Plant Photosynthesis & Plant

PigmentsPigments

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 High Energy CarbohydratesCarbohydrates (sugars, (sugars, e.g. Glucose) & Starchese.g. Glucose) & Starches

Investigating Investigating 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

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

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 A pre- into A pre-measured amount of soil measured amount of soil and and wateredwatered for 5 years for 5 years

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

• Concluded Mass Came Concluded Mass Came From WaterFrom Water

• A candle requires oxygen to burn. Can you think of an experimental design that would prove plants make oxygen?

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.

17791779

Repeated 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

Melvin Calvin 1948Melvin Calvin 1948

•First to trace the path that First to trace the path that carbon (COcarbon (CO22)) takes in takes in forming forming GlucoseGlucose•Does Does NOTNOT require sunlight require sunlight•Called the Called the Calvin CycleCalvin Cycle or or Light Independent ReactionLight Independent Reaction•Also knownAlso known as the as the Dark Dark ReactionReaction

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 Chaintransport Chain

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

The Biochemical The Biochemical ReactionsReactions

It Begins with Sunlight!It Begins with 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

Thylakoid membranesThylakoid membranes

•Light DependentLight Dependent reactions occur herereactions occur here

Photosynthesis Photosynthesis OverviewOverview

•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

Light Dependent Light Dependent ReactionsReactions

Light Dependent Light Dependent ReactionReaction

Light Dependent Light Dependent ReactionReaction

Oh it could get a whole lot more complicated folks!

Light Reaction SummaryLight Reaction SummaryReactants:Reactants:

•HH22OO

•Light EnergyLight Energy

Energy Products:Energy Products:•ATPATP•NADPHNADPH

The Calvin CycleThe Calvin Cycle

Factors Affecting the Factors Affecting the Rate of PhotosynthesisRate of Photosynthesis

•Amount of Amount of available wateravailable water

•TemperatureTemperature•Amount of Amount of available light available light energyenergy