Post on 28-Dec-2015
transcript
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
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
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
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
Exceptions to the Rules:Exceptions to the Rules:
Autotrophic BacteriaAutotrophic Bacteria::Example: Cyanobacteria Example: Cyanobacteria
(“Blue” bacteria)(“Blue” bacteria)
Exceptions to the Rules:Exceptions to the Rules:
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
Exceptions to the Rules:Exceptions to the Rules:
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
Photosynthesis SummaryPhotosynthesis Summary
Light Light ReactionReaction
Calvin Calvin CycleCycle
LocationLocation Thylakoid Thylakoid
ReactanReactantsts
ProductsProducts
Photosynthesis SummaryPhotosynthesis Summary
Light Light ReactionReaction
Calvin Calvin CycleCycle
LocationLocation Thylakoid Thylakoid StromaStroma
ReactanReactantsts
ProductsProducts
Photosynthesis SummaryPhotosynthesis Summary
Light Light ReactionReaction
Calvin Calvin CycleCycle
LocationLocation Thylakoid Thylakoid StromaStroma
ReactanReactantsts
Light, HLight, H22OO
ProductsProducts
Photosynthesis SummaryPhotosynthesis Summary
Light Light ReactionReaction
Calvin Calvin CycleCycle
LocationLocation Thylakoid Thylakoid StromaStroma
ReactanReactantsts
Light, HLight, H22OO COCO22, ATP, , ATP,
NADPHNADPH
ProductsProducts
Photosynthesis SummaryPhotosynthesis Summary
Light Light ReactionReaction
Calvin Calvin CycleCycle
LocationLocation Thylakoid Thylakoid StromaStroma
ReactanReactantsts
Light, HLight, H22OO COCO22, ATP, , ATP,
NADPHNADPH
ProductsProducts ATP, ATP, NADPH, ONADPH, O22
Photosynthesis SummaryPhotosynthesis Summary
Light Light ReactionReaction
Calvin Calvin CycleCycle
LocationLocation Thylakoid Thylakoid StromaStroma
ReactanReactantsts
Light, HLight, H22OO COCO22, ATP, , ATP,
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