BiologyJanuary 26, 2015

Copy and answer the following EQ into your science journal.

EQ: How does the process of photosynthesis relate

to me?

Word of the DaySTOMATA

A microscopic pore on the

surface (epidermis)

of land plants

Diagrams

Draw, color and label the following diagrams into your science journal: Figure 8-4 page 206Figure 8-6 page 208Figure 8-7 page 209Figure 8-10 page 211

PHOTOSYNTHESISPHOTOSYNTHESIS

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PhotosynthesisPhotosynthesis

• AnabolicAnabolic (small molecules combined) (small molecules combined)• EndergonicEndergonic (stores energy) (stores energy)• Carbon dioxide (COCarbon dioxide (CO22)) requiring process requiring process

that uses that uses light energy (photons)light energy (photons) and and water (Hwater (H22O)O) to produce to produce organic organic macromolecules (glucose).macromolecules (glucose).

6CO2 + 6H2O C6H12O6 + 6O2glucoseglucose

SUNphotonsphotons

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Question:Question:

Where does Where does photosynthesis photosynthesis

take place?take place?

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PlantsPlants• Autotrophs Autotrophs – produce their own food – produce their own food

(glucose)(glucose)

• Process called Process called photosynthesisphotosynthesis

• Mainly occurs in the Mainly occurs in the leaves:leaves:

a.a. stoma - poresstoma - pores

b.b. mesophyll cellsmesophyll cells

StomaMesophyllCell

Chloroplast

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Stomata (stoma)Stomata (stoma)PoresPores in a plant’s cuticle through in a plant’s cuticle through

which which water vaporwater vapor and and gasesgases (CO(CO22

& O& O22)) are exchanged between the are exchanged between the

plant and the atmosphere.plant and the atmosphere.

Guard CellGuard CellCarbon Dioxide (CO2)

Oxygen (O2)

Found on the underside of leavesFound on the underside of leaves

StomaStoma

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Mesophyll Cell of LeafMesophyll Cell of Leaf

Cell Wall

NucleusNucleus

Chloroplast

Central Vacuole

Photosynthesis occurs in these cells!Photosynthesis occurs in these cells!

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ChloroplastChloroplast

OrganelleOrganelle where photosynthesisphotosynthesis takes place.

GranumThylakoid

Stroma

Outer Membrane

Inner Membrane

Thylakoid stacks are connected togetherThylakoid stacks are connected together

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ThylakoidThylakoid

Thylakoid Membrane

Thylakoid SpaceGranum

Grana make up the inner membraneGrana make up the inner membrane

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Question:Question:

Why are Why are plants plants green?green?

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Chlorophyll MoleculesChlorophyll Molecules

• Located in the Located in the thylakoid membranesthylakoid membranes• Chlorophyll have Chlorophyll have MgMg++ in the center in the center• Chlorophyll pigments Chlorophyll pigments harvest energy harvest energy

(photons)(photons) by absorbing certain by absorbing certain wavelengths wavelengths (blue-420 nm and red-(blue-420 nm and red-660 nm660 nm are most important) are most important)

• Plants are Plants are greengreen because the because the green green wavelength is reflectedwavelength is reflected, not absorbed, not absorbed.

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Wavelength of Light (nm)Wavelength of Light (nm)

400 500 600 700

Short wave Long wave(more energy) (less energy)

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Absorption of Light by Absorption of Light by ChlorophyllChlorophyll

wavelengthwavelength

Absorption

violet blue green yellow orange red

Chlorophyll absorbs blue-violet & red light bestChlorophyll absorbs blue-violet & red light best

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Question:Question:

During the fall, During the fall, what causes the what causes the leaves to change leaves to change

colors?colors?

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Fall ColorsFall Colors

• In addition to the chlorophyll In addition to the chlorophyll pigments, there are pigments, there are other pigmentsother pigments presentpresent

• During the fall, the During the fall, the green green chlorophyll pigments are greatly chlorophyll pigments are greatly reducedreduced revealing the other revealing the other pigmentspigments

• CarotenoidsCarotenoids are pigments that are are pigments that are either either redred, , orangeorange, or , or yellowyellow

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Redox ReactionRedox Reaction

The The transfertransfer of one or more of one or more electronselectrons from one reactant to from one reactant to anotheranother

Two types:Two types:

1.1. Oxidation is the Oxidation is the lossloss of e of e--

2.2. Reduction is the Reduction is the gaingain of e of e--

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Oxidation ReactionOxidation Reaction

The The loss of electronsloss of electrons from a from a substance or the substance or the gain of gain of oxygen.oxygen.

glucoseglucose

6CO2 + 6H2O C6H12O6 + 6O2

OxidationOxidation

Carbon Carbon dioxidedioxide WaterWater

OxygenOxygen

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Reduction ReactionReduction Reaction

The The gain of electronsgain of electrons to a to a substance or the substance or the loss of loss of oxygen.oxygen.

glucoseglucose

6CO2 + 6H2O C6H12O6 + 6O2

ReductionReduction

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Question:Question:

Why do cells Why do cells use for use for energy?energy?

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Energy for Life on EarthEnergy for Life on Earth

• Sunlight is the ULTIMATE energy for all life on Earth

• Plants store energy in the chemical bonds of sugars

• Chemical energy is released as ATP during cellular respiration

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Structure of ATPStructure of ATP

• ATP stands for adenosine triphosphate

• It is composed of the nitrogen base ADENINE, the pentose (5C) sugar RIBOSE, and three PHOSPHATE groups

• The LAST phosphate group is bonded with a HIGH ENERGY chemical bond

• This bond can be BROKEN to release ENERGY for CELLS to use

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Removing a Phosphate Removing a Phosphate from ATPfrom ATP

Breaking the LAST PHOSPHATE bond from ATP, will ---– Release ENERGY for cells to use– Form ADP– Produce a FREE PHOSPHATE

GROUP

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High Energy Phosphate BondHigh Energy Phosphate Bond

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FREE PHOSPHATE can be re-FREE PHOSPHATE can be re-attached to ADP reforming ATPattached to ADP reforming ATP

Process called Process called PhosphorylationPhosphorylation

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PhosphorylationPhosphorylation

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Parts of Parts of PhotosynthesisPhotosynthesis

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Two Parts of Two Parts of PhotosynthesisPhotosynthesis

Two reactions make up Two reactions make up photosynthesis:photosynthesis:

1.1.Light Reaction or Light Light Reaction or Light Dependent ReactionDependent Reaction - -

Produces energy from solar Produces energy from solar power (photons) in the form of power (photons) in the form of ATP and NADPH.ATP and NADPH.

SUNSUN

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Two Parts of Two Parts of PhotosynthesisPhotosynthesis

2. 2. Calvin Cycle or Light Calvin Cycle or Light Independent Reaction Independent Reaction

• Also called Also called Carbon FixationCarbon Fixation or or CC33 Fixation Fixation

• Uses energy (Uses energy (ATP and ATP and NADPHNADPH) from light reaction to ) from light reaction to make sugar make sugar (glucose).(glucose).

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Light Reaction Light Reaction (Electron Flow)(Electron Flow)

• Occurs in the Occurs in the Thylakoid Thylakoid membranesmembranes

• During the During the light reactionlight reaction, there , there are are twotwo possible routes for possible routes for electron flow:electron flow:

A.A. Cyclic Electron FlowCyclic Electron Flow

B.B. Noncyclic Electron FlowNoncyclic Electron Flow

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Cyclic Electron FlowCyclic Electron Flow

• Occurs in the Occurs in the thylakoidthylakoid membrane. membrane.

• Uses Uses Photosystem I onlyPhotosystem I only

• P700P700 reaction center- chlorophyll a reaction center- chlorophyll a

• Uses Electron Transport Chain Uses Electron Transport Chain (ETC)(ETC)

• Generates Generates ATP onlyATP only

ADP + ADP + ATP ATPP

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Cyclic Electron FlowCyclic Electron Flow

P700

PrimaryElectronAcceptor

e-

e-

e-

e-

ATPATPproducedby ETC

Photosystem I

AccessoryPigments

SUN

Photons

Pigments absorb light energy & excite e- of Pigments absorb light energy & excite e- of Chlorophyll a to produce ATP Chlorophyll a to produce ATP

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Noncyclic Electron FlowNoncyclic Electron Flow• Occurs in the Occurs in the thylakoidthylakoid membrane membrane• Uses Uses Photosystem II Photosystem II and and

Photosystem IPhotosystem I• P680 P680 reaction center reaction center (PSII)(PSII) - -

chlorophyll achlorophyll a• P700P700 reaction center reaction center (PS I)(PS I) - -

chlorophyll achlorophyll a• Uses Electron Transport Chain Uses Electron Transport Chain

(ETC)(ETC)• Generates Generates OO22, ATP and NADPH, ATP and NADPH

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Noncyclic Electron FlowNoncyclic Electron Flow

P700

Photosystem IP680

Photosystem II

PrimaryElectronAcceptor

PrimaryElectronAcceptor

ETC

EnzymeReaction

H2O

1/2O1/2O22 + 2H+

ATPATP

NADPHNADPH

Photon

2e-

2e-

2e-

2e-

2e-

SUN

Photon

HH22O is split in PSII & ATP is made, while the energy carrier NADPH is O is split in PSII & ATP is made, while the energy carrier NADPH is

made in PSImade in PSI

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Noncyclic Electron FlowNoncyclic Electron Flow

• ADP +ADP + ATPATP

• NADPNADP++ + H + H NADPHNADPH

• OxygenOxygen comes from the splitting comes from the splitting of Hof H22O, not COO, not CO22

HH22O O 1/2 O 1/2 O22 + 2H + 2H++

PP

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ChemiosmosisChemiosmosis

• Powers Powers ATP synthesisATP synthesis

• Takes place across the thylakoid Takes place across the thylakoid membranemembrane

• Uses Uses ETCETC and and ATP synthase ATP synthase (enzyme)(enzyme)

• H+H+ move down their move down their concentration gradient through concentration gradient through channels of ATP synthasechannels of ATP synthase forming forming ATP from ADPATP from ADP

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ChemiosmosisChemiosmosisH+ H+

ATP Synthase

H+ H+ H+ H+

H+ H+ high Hhigh H++

concentrationconcentration

H+ADP + P ATP

PS II PS IE

TC

low Hlow H++

concentrationconcentration

H+ThylakoidThylakoidSpaceSpace

ThylakoidThylakoid

SUN (Proton Pumping)

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Calvin CycleCalvin Cycle• Carbon Fixation Carbon Fixation (light independent (light independent

reaction)reaction)• CC33 plants (80% of plants on earth) plants (80% of plants on earth)• Occurs in the Occurs in the stromastroma• Uses Uses ATP and NADPHATP and NADPH from light from light

reaction as energyreaction as energy• Uses Uses COCO22

• To produce To produce glucoseglucose: it takes : it takes 6 turns 6 turns and uses 18 ATP and 12 NADPH. and uses 18 ATP and 12 NADPH.

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ChloroplastChloroplast

GranumThylakoid

STROMA– where Calvin Cycle occursOuter Membrane

Inner Membrane

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Calvin Cycle (CCalvin Cycle (C33 fixation) fixation)

6CO2

6C-C-C-C-C-C

6C-C-C 6C-C-C

6C-C-C-C-C

12PGA

RuBP

12G3P

(unstable)

6NADPH 6NADPH

6ATP 6ATP

6ATP

C-C-C-C-C-CGlucose

(6C)(36C)

(36C)

(36C)

(30C)

(30C)

(6C)

6C-C-C 6C-C-C

C3

glucose

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Calvin CycleCalvin Cycle

Remember: CRemember: C33 = Calvin Cycle = Calvin Cycle

C3

Glucose

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PhotorespirationPhotorespiration

• Occurs on hot, dry, bright daysOccurs on hot, dry, bright days

• Stomates closeStomates close

• Fixation of OFixation of O22 instead of CO instead of CO22

• Produces Produces 2-C molecules 2-C molecules instead of 3-C sugar moleculesinstead of 3-C sugar molecules

• Produces Produces no sugarno sugar molecules molecules or or no ATPno ATP

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PhotorespirationPhotorespiration

Because of photorespiration, plants Because of photorespiration, plants have special adaptations to limit the have special adaptations to limit the effect of photorespiration:effect of photorespiration:

1.1. CC44 plants plants

2.2. CAM plantsCAM plants

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CC44 Plants Plants

• Hot, moist Hot, moist environmentsenvironments

• 15% of plants 15% of plants ((grasses, corn, grasses, corn, sugarcane)sugarcane)

• Photosynthesis Photosynthesis occurs in 2 placesoccurs in 2 places

• Light reactionLight reaction - - mesophyll cellsmesophyll cells

• Calvin cycleCalvin cycle - - bundle sheath cellsbundle sheath cells

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CC44 Plants Plants

Mesophyll CellMesophyll Cell

CO2

C-C-C

PEP

C-C-C-CMalate-4C sugar

ATP

Bundle Sheath CellBundle Sheath Cell

C-C-C

Pyruvic Acid

C-C-C-C

CO2

C3

Malate

Transported

glucoseVascular Tissue

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CAM PlantsCAM Plants

• Hot, dry environmentsHot, dry environments• 5%5% of plants (cactus and ice of plants (cactus and ice

plants)plants)• Stomates closed during dayStomates closed during day• Stomates open during the nightStomates open during the night• Light reaction - occurs during the Light reaction - occurs during the

dayday• Calvin Cycle - occurs when COCalvin Cycle - occurs when CO22 is is

presentpresent

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CAM PlantsCAM PlantsNight (Stomates Open) Day (Stomates Closed)

Vacuole

C-C-C-CMalate

C-C-C-CMalate Malate

C-C-C-CCO2

CO2

C3

C-C-CPyruvic acid

ATPC-C-CPEP glucose

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Question:Question:

Why do CAM Why do CAM plants close their plants close their stomata during stomata during

the day?the day?

Cam plants close Cam plants close their stomata in their stomata in the hottest part the hottest part

of the day to of the day to conserve waterconserve water