Process of Photosynthesis. Photosynthesis Equation Photosynthesis is the process of capturing light energy and converting it into chemical energy, (usually

Process of Process of PhotosynthesisPhotosynthesis

Photosynthesis EquationPhotosynthesis Equation Photosynthesis is the process of Photosynthesis is the process of

capturing light energy and capturing light energy and converting it into chemical energy, converting it into chemical energy, (usually in the form of (usually in the form of carbohydrates)carbohydrates)

6 CO6 CO22 + 6 H + 6 H22O + O + LightLight C C66HH1212OO66

+ 6O+ 6O22

Photosynthesis is broken Photosynthesis is broken down into two reactions.down into two reactions.

Light Dependent ReactionLight Dependent Reaction -energy from -energy from light makes the reaction happenlight makes the reaction happen

Light Independent Reaction (Calvin Cycle; Light Independent Reaction (Calvin Cycle; Dark Reaction)Dark Reaction) Doesn’t need direct light Doesn’t need direct light energy, but it does need the high-energy energy, but it does need the high-energy products from the Light Rx.products from the Light Rx. ATP and NADPH ATP and NADPH

Light Dependent Reactions- Light Dependent Reactions- In the ChloroplastIn the Chloroplast

1.1. Light energy is absorbed Light energy is absorbed by _________ in the by _________ in the thylakoid membranes of thylakoid membranes of the chloroplast (pigments the chloroplast (pigments are located in are located in Photosystem I & II)Photosystem I & II)

pigmentspigments

2.2. In Photosystem II the In Photosystem II the electrons become electrons become ________________or ________________or “excited”.“excited”.

energizedenergized

3.3. The excited electrons The excited electrons are passed down a are passed down a series of molecules series of molecules called the called the _________________________________________________._________.Electron Transport Electron Transport ChainChain

4.4. To replace the electrons To replace the electrons that are lost, some are that are lost, some are stolen from water . This stolen from water . This breaks the water molecule breaks the water molecule apart like this: apart like this:

2H2H22O O 4H 4H++ + O + O22

5.5.As electrons move As electrons move down the chain, their down the chain, their energy is used to energy is used to make ______ (a high- make ______ (a high- energy molecule)energy molecule)

ATPATP

6.6. The electrons now go The electrons now go to Photosystem I. Light to Photosystem I. Light energizes new energizes new electrons in PI and they electrons in PI and they combine with NADP+ to combine with NADP+ to make ________ make ________ (another high-energy (another high-energy molecule). molecule).

NADPHNADPH

LIGHT RXLIGHT RX

http://www.cnr.vt.edu/DENDRO/forestbiology/photosynthesis.swf

The final products of the The final products of the light reactionlight reaction

At the end of the light At the end of the light reaction we have made:reaction we have made:

1.1. ATPATP

2.2. NADPH NADPH

3.3. OO22

Reactants used during Reactants used during the light reaction:the light reaction:

1.1. WaterWater

2.2. Also used sunlightAlso used sunlight

Light independent Light independent reaction ( Calvin Cycle)reaction ( Calvin Cycle)

A. Needs: COA. Needs: CO2 2 , ATP, NADPH, ATP, NADPHB. Where do they come from?B. Where do they come from? Light Reaction- ATP NADPHLight Reaction- ATP NADPH Air-CO2Air-CO2C. Where do they go?C. Where do they go? Calvin CycleCalvin Cycle

Location stromaLocation stromaEnzymes are found in the stromaEnzymes are found in the stroma

Calvin cycle (dark reaction)Calvin cycle (dark reaction): : doesn’t need lightdoesn’t need light

- Uses the ATP and NADPH “charged” - Uses the ATP and NADPH “charged” by the light reactions to link COby the light reactions to link CO22

together to build Ctogether to build C66HH1212OO66

Reactant: 6COReactant: 6CO22 Product: CProduct: C66HH1212OO66

What happens to the glucose?What happens to the glucose?

1.1. Move to the mitochondria to be converted Move to the mitochondria to be converted into ATP through Cell respirationinto ATP through Cell respiration

22. Go through dehydration synthesis to build a . Go through dehydration synthesis to build a big starch chain and be stored for future usebig starch chain and be stored for future use

Chloroplast

Chloroplast

Photosynthesis: An Overview

Light

O2Sugars

CO2

Light-Dependent Reactions

CalvinCycle

NADPH

ATP

ADP + PNADP+

H2O

Factors affecting Photosynthesis: Factors affecting Photosynthesis: Light IntensityLight Intensity: the rate of : the rate of

photosynthesis _________as light photosynthesis _________as light intensity_________, then levels offintensity_________, then levels off

COCO22 levels: levels: the rate of the rate of

photosynthesis _________ as COphotosynthesis _________ as CO22

_________, then levels off_________, then levels off

increasesincreases

increasesincreases

increasesincreasesincreasesincreases

What causes the rate to What causes the rate to level off in each case?level off in each case? With more light, the plant is limited With more light, the plant is limited

by the amount of COby the amount of CO22 available. available. Don’t forget that the wavelength of Don’t forget that the wavelength of

light matters!!!light matters!!!

With more COWith more CO22, the plant is limited , the plant is limited

by the amount light energy by the amount light energy available.available.

Temperature:Temperature: increasing the increasing the temperature, _________the rate temperature, _________the rate of photosynthesis, then the rate of photosynthesis, then the rate peaks and ____________.peaks and ____________.

increasesincreases

decreasesdecreases

Why does the rate decrease Why does the rate decrease after a certain temperature?after a certain temperature?

The enzymes and other The enzymes and other molecules controlling the molecules controlling the reaction start to break reaction start to break down after that down after that temperature. temperature.

Alternative PathwaysAlternative Pathways

Some plants that live in ____, Some plants that live in ____, ____ environments have ____ environments have modified internal structures and modified internal structures and use alternative carbon fixation use alternative carbon fixation pathways.pathways.

Better at preventing _________.Better at preventing _________.

hothotdrydry

water losswater loss

Leaf structureLeaf structure

Stoma (stomata pl.)Stoma (stomata pl.)

How does a plant stop water loss?How does a plant stop water loss?Close the stomata.Close the stomata.

But what problem does that cause?But what problem does that cause?Run out of CORun out of CO22 and too much O and too much O22

builds up.builds up.

C4 pathwayC4 pathway The C4 pathway uses a The C4 pathway uses a

special ____-carbon special ____-carbon compound to “fix” carbon into compound to “fix” carbon into glucose.glucose.

This is more efficient when This is more efficient when the level of COthe level of CO22 is low. is low.

fourfour

Examples: Examples: corn, crab grass, sugar corn, crab grass, sugar canecane

CAM pathwaysCAM pathways

________ stomata at ________ stomata at night to store COnight to store CO2.2.

Close stomata in the day, Close stomata in the day, which prevents water loss. which prevents water loss.

OpensOpens

Examples: Examples: pineapple, cactipineapple, cacti

Exceptions to the Rules:Exceptions to the Rules:

Autotrophic BacteriaAutotrophic Bacteria::Example: Cyanobacteria Example: Cyanobacteria

(“Blue” bacteria)(“Blue” bacteria)


Autotrophic ProtistsAutotrophic Protists: : Example: Algae and Example: Algae and

EuglenaEuglena

Exceptions to the Rules:Exceptions to the Rules: Heterotrophic plantsHeterotrophic plants: some plants : some plants

get food from other organismsget food from other organismsMistletoeMistletoe: makes food AND : makes food AND

takes sap (high in sugar) from takes sap (high in sugar) from other treesother trees


Venus FlytrapVenus Flytrap: traps and digests : traps and digests insects as a food sourceinsects as a food source

Photosynthesis SummaryPhotosynthesis Summary

Light Light ReactionReaction

Calvin Calvin CycleCycle

LocationLocation

ReactanReactantsts

ProductsProducts




LocationLocation Thylakoid Thylakoid

ReactanReactantsts

ProductsProducts




LocationLocation Thylakoid Thylakoid StromaStroma

ReactanReactantsts

ProductsProducts





ReactanReactantsts

Light, HLight, H22OO

ProductsProducts





ReactanReactantsts

Light, HLight, H22OO COCO22, ATP, , ATP,

NADPHNADPH

ProductsProducts





ReactanReactantsts


NADPHNADPH

ProductsProducts ATP, ATP, NADPH, ONADPH, O22





ReactanReactantsts


NADPHNADPH

ProductsProducts ATP, ATP, NADPH, ONADPH, O22

GlucoseGlucose

Chloroplast

Chloroplast

Photosynthesis: An Overview

Light

O2Sugars

CO2

Light-Dependent Reactions

CalvinCycle

NADPH

ATP

ADP + PNADP+

H2O

Photosynthesis

includes

of

take place intakes place in uses

to produce to produce

use

Light-dependentreactions

Calvin cycle

Thylakoidmembranes Stroma NADPHATPEnergy from

sunlight

ATP NADPH O2 Chloroplasts High-energysugars

Concept Map

Documents

Process of Photosynthesis. Photosynthesis Equation Photosynthesis is the process of capturing light energy and converting it into chemical energy, (usually