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PhotosynthesisPhotosynthesisPhotosynthesisPhotosynthesis
A definition:Photosynthesis is the process a plant uses to make food and
grow.
A definition:Photosynthesis is the process a plant uses to make food and
grow.
Four things are needed for photosynthesis:
Travels up from the roots
WATER
CARBON DIOXIDE
Enters the leaf through small holes on the underneath
SUNLIGHT
Gives the plant energy CHLOROPHYLL
The green stuff where the chemical reactions happen
The word and chemical equations for photosynthesis:
Carbon dioxide + water glucose + oxygen
6CO2 + 6H20 C6H12O6 + 6O2
Sunlight
Chlorophyll
Sunlight
Chlorophyll
THE SUN: MAIN SOURCE OF ENERGY FOR LIFE ON EARTHTHE SUN: MAIN SOURCE OF ENERGY FOR LIFE ON EARTH
Almost all plants are photosynthetic autotrophs, as are some bacteria and protists
Autotrophs generate their own organic matter through photosynthesisSunlight energy is transformed to energy stored in the form of chemical bonds
(a) Mosses, ferns, andflowering plants
(b) Kelp
(c) Euglena (d) Cyanobacteria
THE BASICS OF PHOTOSYNTHESIS
Photosynthesis is the process by which autotrophic organisms use light energy to make sugar and oxygen gas from carbon dioxide and water
Photosynthesis is the process by which autotrophic organisms use light energy to make sugar and oxygen gas from carbon dioxide and water
AN OVERVIEW OF PHOTOSYNTHESIS
Carbondioxide
Water Glucose Oxygengas
PHOTOSYNTHESIS
The Calvin cycle makes sugar from carbon dioxide
ATP generated by the light reactions provides the energy for sugar synthesisThe NADPH produced by the light reactions provides the electrons for the reduction of carbon dioxide to glucose
LightChloroplast
Lightreactions
Calvincycle
NADP
ADP+ P
The light reactions convert solar energy to chemical energy Produce ATP & NADPH
The light reactions convert solar energy to chemical energy Produce ATP & NADPH
AN OVERVIEW OF PHOTOSYNTHESIS
Light Energy Harvested by Plants & Other Photosynthetic Autotrophs
Light Energy Harvested by Plants & Other Photosynthetic Autotrophs
6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2
WHWHY ARY ARE PE PLANLANTS GTS GREREEN?EN?
It has to do with sunlight!
Sunlight is a form of electromagnetic energy, which travels in waves.
Electromagnetic Spectrum and Visible Light
Electromagnetic Spectrum and Visible LightGamma
rays X-rays UVInfrared &
Microwaves Radio waves
Visible light
Wavelength (nm):Distance between two waves
Different wavelengths of visible light are seen by the human eye as different colors.
WHYWHY ARE ARE PLA PLANTS NTS GREGREEN?EN?
Gammarays
X-rays UV Infrared Micro-waves
Radiowaves
Visible light
Wavelength (nm)
Sunlight minus absorbed Sunlight minus absorbed wavelengths or colors wavelengths or colors equals the apparent color equals the apparent color of an object.of an object.
The feathers of male cardinals are loaded with carotenoid pigments. These pigments absorb some wavelengths of light and reflect others.
Reflected light
Chloroplasts absorb light energy and convert it to chemical energy
Chloroplasts absorb light energy and convert it to chemical energy
LightReflected
light
Absorbedlight
Transmittedlight
Chloroplast
THE COLOR OF LIGHT SEEN IS THE COLOR NOT ABSORBED
In most plants, photosynthesis occurs primarily in the leaves, in the chloroplasts
A chloroplast contains: stroma, a fluid (site of Calvin Cycle)grana, stacks of thylakoids (site of Light reactions)
The thylakoids contain chlorophyllChlorophyll is the green pigment that captures light for photosynthesis
In most plants, photosynthesis occurs primarily in the leaves, in the chloroplasts
A chloroplast contains: stroma, a fluid (site of Calvin Cycle)grana, stacks of thylakoids (site of Light reactions)
The thylakoids contain chlorophyllChlorophyll is the green pigment that captures light for photosynthesis
Photosynthesis occurs in chloroplasts
Photosynthesis occurs in chloroplasts
The location and structure of chloroplasts
The location and structure of chloroplasts
LEAF CROSS SECTION MESOPHYLL CELL
LEAF
Chloroplast
Mesophyll
CHLOROPLAST Intermembrane space
Outermembrane
Innermembrane
ThylakoidcompartmentThylakoidStroma
Granum
StromaGrana
Chloroplasts contain several pigmentsChloroplasts contain several pigments
Chloroplast PigmentsChloroplast Pigments
Chlorophyll a: absorbs mainly violet and red light the bestChlorophyll b: absorbs blue and orange light the bestCarotenoids: absorbs blue and green best
Figure 7.7
Different pigments absorb light differently
Different pigments absorb light differently
Paper ChromatographyPaper Chromatography
A laboratory test used to separate and analyze different pigments in a leaf.
Example:https://www.pearsonsuccessnet.com/snpapp/iText/getTeacherHomepage.do?newServiceId=6000&newPageId=10100
A laboratory test used to separate and analyze different pigments in a leaf.
Example:https://www.pearsonsuccessnet.com/snpapp/iText/getTeacherHomepage.do?newServiceId=6000&newPageId=10100
Photosystems:Clusters of pigments in
thylakoid membrane
Photosystems:Clusters of pigments in
thylakoid membranePhotosystem I
- Traps light energy and transfers the light-excited electrons to an electron transport chain.
- Those excited electrons are replaced by splitting a molecule of water, which releases oxygen.
- The electron transport chain releases energy, which is used to make ATP
Photosystem II
- Produces NADPH by transferring excited electrons and hydrogen ions to NADP+.
Photosystem I
- Traps light energy and transfers the light-excited electrons to an electron transport chain.
- Those excited electrons are replaced by splitting a molecule of water, which releases oxygen.
- The electron transport chain releases energy, which is used to make ATP
Photosystem II
- Produces NADPH by transferring excited electrons and hydrogen ions to NADP+.
Light Reactions Photosystem I and Photosystem IILight Reactions Photosystem I and Photosystem II
SUMMARY: In the light reactions, electron In the light reactions, electron transport chains generate ATP, NADPH, & Otransport chains generate ATP, NADPH, & O22
Two connected photosystems collect photons of light and transfer the energy to chlorophyll electrons
The excited electrons are passed from the primary electron acceptor to electron transport chains
The light reactions convert light energy to the chemical energy of ATP and NADPH
Watch the following animation:http://www.youtube.com/watch?v=eY1ReqiYwYs
SUMMARY: In the light reactions, electron In the light reactions, electron transport chains generate ATP, NADPH, & Otransport chains generate ATP, NADPH, & O22
Two connected photosystems collect photons of light and transfer the energy to chlorophyll electrons
The excited electrons are passed from the primary electron acceptor to electron transport chains
The light reactions convert light energy to the chemical energy of ATP and NADPH
Watch the following animation:http://www.youtube.com/watch?v=eY1ReqiYwYs
Ph
oto
n
Ph
oto
n
Water-splittingphotosystem
NADPH-producingphotosystem
ATPmill
Two types of photosystems cooperate in the light reactions
Inputs:WaterSunlight energy
Outputs:OxygenATPNADPH
Two types of photosystems cooperate in the light reactions
Inputs:WaterSunlight energy
Outputs:OxygenATPNADPH
The O2 liberated by photosynthesis is made from the oxygen in water (H+ and e-)
The O2 liberated by photosynthesis is made from the oxygen in water (H+ and e-)
Plants produce OPlants produce O22 gas by gas by splitting Hsplitting H22OO
Plants produce OPlants produce O22 gas by gas by splitting Hsplitting H22OO
2 H + 1/2
Water-splittingphotosystem
Reaction-center
chlorophyll
Light
Primaryelectronacceptor
Energyto make
Electron transport chain
Primaryelectronacceptor
Primaryelectronacceptor
NADPH-producingphotosystem
Light
NADP
1
23
How the Light Reactions Generate ATP and NADPH
How the Light Reactions Generate ATP and NADPH
The production of ATP in photosynthesis
The production of ATP in photosynthesis
Thylakoidcompartment(high H+)
Thylakoidmembrane
Stroma(low H+)
Light
Antennamolecules
Light
ELECTRON TRANSPORT CHAIN
PHOTOSYSTEM II PHOTOSYSTEM I ATP SYNTHASE
A Photosynthesis Road MapA Photosynthesis Road Map
Chloroplast
Light
Stack ofthylakoids ADP
+ P
NADP
Stroma
Lightreactions
Calvincycle
Sugar used for
Cellular respiration Cellulose
Starch
Other organic compounds
Calvin CycleCalvin Cycle• Called a cycle because the starting material, RuBP, is
regenerated.
• Uses carbon from carbon dioxide, the energy from ATP, and high energy electrons and hydrogen ions from NADPH to make a small sugar named G3P.
• The plant uses G3P to make glucose and other organic molecules.
Overall input:
CO2, ATP, NADPH
Overall output:
Glucose
• Called a cycle because the starting material, RuBP, is regenerated.
• Uses carbon from carbon dioxide, the energy from ATP, and high energy electrons and hydrogen ions from NADPH to make a small sugar named G3P.
• The plant uses G3P to make glucose and other organic molecules.
Overall input:
CO2, ATP, NADPH
Overall output:
Glucose
Calvin Cycle Calvin Cycle
Watch the following animation:http://www.youtube.com/watch?v=mHU27qYJNU0&NR=1 Watch the following animation:http://www.youtube.com/watch?v=mHU27qYJNU0&NR=1
Review: Photosynthesis uses light energy to make food
molecules
Review: Photosynthesis uses light energy to make food
molecules
Light
Chloroplast
Photosystem IIElectron transport
chains Photosystem I
CALVIN CYCLE Stroma
Electrons
LIGHT REACTIONS CALVIN CYCLE
Cellular respiration
Cellulose
Starch
Other organic compounds
Light reactions use water and produce oxygen.
The Calvin Cycle uses ATP and NADPH created in the the light reactions to convert carbon dioxide to glucose.
Light reactions use water and produce oxygen.
The Calvin Cycle uses ATP and NADPH created in the the light reactions to convert carbon dioxide to glucose.
Animation is of the Calvin Cycle Note what happens to the carbon dioxide and what the end product is.
Second animation of the Calvin Cycle is very clear and even does the molecular bookkeeping for you.
Animation is of the Calvin Cycle Note what happens to the carbon dioxide and what the end product is.
Second animation of the Calvin Cycle is very clear and even does the molecular bookkeeping for you.
