PHOTOSYNTHESIS

PHOTOSYNTHESISUsing Light to Make Food

Photosynthesis is the most important chemical process on earth because:

• It provides food for virtually all organisms

Why study Photosynthesis?

• Impact on agriculture – making photosynthesis more efficient

• Impact on energy production• Control pollution• Electronics • Medicine

BIG PICTURE:

Light energyLight energy is is used to make used to make sugarsugar and other and other food molecules food molecules from from carbon carbon dioxidedioxide andand waterwater

Chemical Reaction

• 6 H2O + 6 CO2 ---------->

C6H12O6+ 6 O2

sunlightsunlight

Photosynthesis: An Overview of Photosynthesis (click)(click)

http://www.phschool.com/science/biology_place/biocoach/photosynth/overview.html

http://www.phschool.com/science/biology_place/biocoach/photosynth/overview.html

Photosynthetic Plants

DiatomsDiatoms

(microscopic(microscopic))

Kelp (oceanKelp (ocean)) Forests Forests (land)(land)

Leaf Structure

1. Stoma in leaf lower epidermis

• Is the opening• carbon dioxide,

oxygen. And water in/out

Stomata (pl.)Stomata (pl.)

Leaf Cross section2. Upper 2. Upper EpidermisEpidermis

4. Mesophyll-4. Mesophyll-cells cells containing containing chloroplastschloroplasts

3. Lower 3. Lower epidermisepidermis

Covers and protectsCovers and protects

see stoma –in lower see stoma –in lower epidermis onlyepidermis only

4. Mesophyll

• = Palisade Layer + Spongy Layer

5. CuticleWaxy, Waxy, waterproof waterproof coating (to retain coating (to retain HH22O)O)

6. Palisade Layer

• cylindrical cells, vertically oriented, closely packed

7. Spongy Layer

• cells are irregular in shape and loosely packed

OO22 ,CO ,CO2, 2, HH220 vapor 0 vapor

go in/outgo in/out

8. Guard Cells Control Stomata

• Full guard cells (turgid) opens the stoma.

• Flaccid (lost water) guard cells, the stoma closes.

• ANIMATION: Stoma• What causes them to open?

What goes into the stomata?

http://www.tvdsb.on.ca/westmin/science/sbioac/plants/stoma.htm

9. Plant Vein: Xylem + Phloem

XylemXylem-(-(blueblue) ) carries carries waterwater

Phloem Phloem (thicker cell (thicker cell

wallwall))-(-(yellowyellow)) carries foodcarries food

10: Air Space Gas Flow Through Leaf

Guard Cells Animations

• LabBench (guard cell animation)

• Another animation of opening and closing of guard cells

http://academic.kellogg.cc.mi.us/herbrandsonc/bio111/animations/0021.swf

(really nice)

http://www.phschool.com/science/biology_place/labbench/lab9/stomamov.html



Water Movement

• LINK: http://www.sciencemag.org/sciext/vis2005/show/transpiration.swf

http://www.sciencemag.org/sciext/vis2005/show/transpiration.swf

http://www.sciencemag.org/sciext/vis2005/show/transpiration.swf

Elodea Cell 400X

Leaf cross section

Photosynthesis in Elodea LabSee oxygen bubbles See oxygen bubbles coming from the Elodeacoming from the Elodea

What conditions are best?What conditions are best?

Elodea Bubbles Movie

• sLowlife Exhibit

http://plantsinmotion.bio.indiana.edu/usbg/photosyn2.htm

Autotrophs and Heterotrophs

– Living things need energy to survive.– This energy comes from food. The energy in most

food comes from the sun.– Where do plants get the energy they need to

produce food?

Autotrophs and Heterotrophs• Autotrophs and Heterotrophs

– Plants and some other types of organisms are able to use light energy from the sun to produce food.

Autotrophs and Heterotrophs

• Organisms, such as plants, which make their own food, are called autotrophs.

• Organisms, such as animals, that must obtain energy from the foods they consume are heterotrophs.

Chemical Energy and ATP

• Chemical Energy and ATP • Energy comes in many forms including light, heat, and

electricity. • Energy can be stored in chemical compounds, too.

Organisms that make their own food are called….

1 2 3 4

25% 25%25%25%1.autotrophs.2.heterotrophs.3.decomposers.4.consumers.

8-1

– Organisms that make their own food are called• autotrophs.• heterotrophs.• decomposers.• consumers.

Most autotrophs obtain their energy from…..

1 2 3 4

25% 25%25%25%1.chemicals in the environment.2. sunlight.3. carbon dioxide in the air.4. other producers.

8-1

– Most autotrophs obtain their energy from• chemicals in the environment.• sunlight.• carbon dioxide in the air.• other producers.


• An important chemical compound that cells use to store and release energy is adenosine triphosphate, abbreviated ATP.

• ATP is used by all types of cells as their basic energy source.


• ATP consists of:– adenine

– ribose (a 5-carbon sugar)

– 3 phosphate groups

Adenine

ATP

Ribose 3 Phosphate groups


• The three phosphate groups are the key to ATP's ability to store and release energy.

Chemical Energy and ATP– Storing Energy

• ADP has two phosphate groups instead of three.• A cell can store small amounts of energy by adding a

phosphate group to ADP.

ADPATP

Energy

Energy

Partiallycharged battery

Fullycharged battery

+

Adenosine Diphosphate (ADP) + Phosphate

Adenosine Triphosphate (ATP)


– Releasing Energy• Energy stored in ATP is released by breaking the

chemical bond between the second and third phosphates.

P

ADP

2 Phosphate groups

How is energy released from ATP?

1 2 3 4

25% 25%25%25%1. A phosphate is added.2. An adenine is added.3. A phosphate is removed.4. A ribose is removed

8-1

– How is energy released from ATP?• A phosphate is added.• An adenine is added.• A phosphate is removed.• A ribose is removed.


– What is the role of ATP in cellular activities?

Chemical Energy and ATP The energy from ATP is needed for many cellular activities,

including active transport across cell membranes, protein synthesis and muscle contraction.

ATP’s characteristics make it exceptionally useful as the basic energy source of all cells.

Using Biochemical Energy

• Using Biochemical Energy• Most cells have only a small amount of ATP, because it

is not a good way to store large amounts of energy.• Cells can regenerate ATP from ADP as needed by using

the energy in foods like glucose.

How is it possible for most cells to function with only a small amount of ATP?

1 2 3 4

25% 25%25%25%1.Cells do not require ATP for

energy.2.ATP can be quickly regenerated

from ADP and P.3.Cells use very small amounts of

energy.4.ATP stores large amounts of

energy.

8-1

– How is it possible for most cells to function with only a small amount of ATP?

• Cells do not require ATP for energy.

• ATP can be quickly regenerated from ADP and P.

• Cells use very small amounts of energy.

• ATP stores large amounts of energy.

Compared to the energy stored in a molecule of glucose, ATP stores

1 2 3 4

25% 25%25%25%1.much more energy.2.much less energy.3.about the same amount of

energy.4.more energy sometimes and less

at others.

8-1

– Compared to the energy stored in a molecule of glucose, ATP stores

• much more energy.• much less energy.• about the same amount of energy.• more energy sometimes and less at others.

REVIEW

• Let’s review section 8.1

Organisms that make their own food are called….

1 2 3 4

25% 25%25%25%1.autotrophs.2.heterotrophs.3.decomposers.4.consumers.

Most autotrophs obtain their energy from…..

1 2 3 4

25% 25%25%25%1.chemicals in the environment.2. sunlight.3. carbon dioxide in the air.4. other producers.

How is energy released from ATP?

….

1 2 3 4

25% 25%25%25%1. A phosphate is added.2. An adenine is added.3. A phosphate is removed.4. A ribose is removed

How is it possible for most cells to function with only a

small amount of ATP?

1 2 3 4

25% 25%25%25%1.Cells do not require ATP for

energy.2.ATP can be quickly regenerated

from ADP and P.3.Cells use very small amounts of

energy.4.ATP stores large amounts of

energy.

Compared to the energy stored in a molecule of glucose, ATP stores

1 2 3 4

25% 25%25%25%1.much more energy.2.much less energy.3.about the same amount of

energy.4.more energy sometimes and less

at others.

8-2 Photosynthesis: An Overview

8-2 Photosynthesis: An Overview

• The key cellular process identified with energy production is photosynthesis.

• Photosynthesis is the process in which green plants use the energy of sunlight to convert water and carbon dioxide into high-energy carbohydrates and oxygen.

Investigating Photosynthesis

– What did the experiments of van Helmont, Priestley, and Ingenhousz reveal about how plants grow?


• Investigating Photosynthesis• Research into photosynthesis began centuries ago.


– Van Helmont’s Experiment• In the 1600s, Jan van Helmont wanted to find out if

plants grew by taking material out of the soil.• He determined the mass of a pot of dry soil and a small

seedling, planted the seedling in the pot, and watered it regularly.

• After five years, the seedling was a small tree and had gained 75 kg, but the soil’s mass was almost unchanged.


• Van Helmont concluded that the gain in mass came from water because water was the only thing he had added.

• His experiment accounts for the “hydrate,” or water, portion of the carbohydrate produced by photosynthesis.

• But where does the carbon of the “carbo-” portion come from?


• Although van Helmont did not realize it, carbon dioxide in the air made a major contribution to the mass of his tree.

• In photosynthesis, the carbon in carbon dioxide is used to make sugars and other carbohydrates.

• Van Helmont had only part of the story, but he had made a major contribution to science.

8-2

– In van Helmont's experiment, most of the added mass of the tree came from

• soil and carbon dioxide.• water and carbon dioxide.• oxygen and carbon dioxide.• soil and oxygen.


– Priestley’s Experiment• More than 100 years after van Helmont’s experiment,

Joseph Priestley provided another insight into the process of photosynthesis.

• Priestley took a candle, placed a glass jar over it, and watched as the flame gradually died out.

• He reasoned that the flame needed something in the air to keep burning and when it was used up, the flame went out. That substance was oxygen.


• Priestley then placed a live sprig of mint under the jar and allowed a few days to pass.

• He found that the candle could be relighted and would remain lighted for a while.

• The mint plant had produced the substance required for burning. In other words, it had released oxygen.


– Jan Ingenhousz• Later, Jan Ingenhousz showed that the effect observed

by Priestley occurred only when the plant was exposed to light.

• The results of both Priestley’s and Ingenhousz’s experiments showed that light is necessary for plants to produce oxygen.


– The experiments performed by van Helmont, Priestley, and Ingenhousz led to work by other scientists who finally discovered that, in the presence of light, plants transform carbon dioxide and water into carbohydrates, and they also release oxygen.

The Photosynthesis Equation

– What is the overall equation for photosynthesis?


• The Photosynthesis Equation• The equation for photosynthesis is:

• 6CO2 + 6H2O C6H12O6 + 6O2

• carbon dioxide + water sugars + oxygen

Light

Light


– Photosynthesis uses the energy of sunlight to convert water and carbon dioxide into high-energy sugars and oxygen.

Plants use the sugars produced in photosynthesis to make….

1 2 3 4

25% 25%25%25%

1. oxygen.2. starches.3. carbon dioxide.4. protein.

8-2

– Plants use the sugars produced in photosynthesis to make

• oxygen.• starches.• carbon dioxide.• protein.

The raw materials required for plants to carry out photosynthesis are…

.

1 2 3 4

25% 25%25%25%

1. carbon dioxide and oxygen.2. oxygen and sugars.3. carbon dioxide and water.

4. oxygen and water..

8-2

– The raw materials required for plants to carry out photosynthesis are

• carbon dioxide and oxygen.• oxygen and sugars.• carbon dioxide and water.• oxygen and water.

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8-1 Energy and Life The Photosynthesis Equation

O2

CO2

+H20

Sugar

ADPNADP+

Light energy

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8-1 Energy and Life Light and Pigments

What is the role of light and chlorophyll in photosynthesis?

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Light and Pigments

How do plants capture the energy of sunlight?

In addition to water and carbon dioxide, photosynthesis requires light and chlorophyll.

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Plants gather the sun's energy with light-absorbing molecules called pigments.

The main pigment in plants is chlorophyll.

There are two main types of chlorophyll:

• chlorophyll a

• chlorophyll b

The principal pigment in plants is….

1 2 3 4

25% 25%25%25%

1. chloroplast.2. chlorophyll.3. carotene.4. carbohydrate.

8-2

– The principal pigment in plants is• chloroplast.• chlorophyll.• carotene.• carbohydrate.

Pigments in Plants• Pigments are light-absorbing

molecules• Different

pigments absorb or reflect different colors

Chlorophyll a

• wavelengths absorbed:

blue-violet and red

• Reflects: grass green WavelengthWavelength

Chlorophyll b

• Absorbs: blue and orange

• Reflects: yellow-green

•An accessory chlorophyll in plants

Other pigments in plants

• Absorb: blue-green

• Reflect: yellow-orange

Carotenoids-orangeCarotenoids-orange

FYI Why do leaves change color?

• As fall comes there are shorter days of sunlight

• Less photosynthesis means less food for plants.

• Chlorophyll breaks down and exposes the other colors that were there all along, but were masked by the green chlorophyll.

WORKSHEET

• “Absorption of Chlorophyll”

• Photosynthesis: The Action Spectrum for Photosynthesis (experiment link)

http://www.phschool.com/science/biology_place/biocoach/photosynth/action.html



Light and Pigments

• Chlorophyll absorbs light well in the blue-violet and red regions of the visible spectrum.

Wavelength (nm)

Est

imat

ed A

bso

rpti

on

(%

) 100

80

60

40

20

0400 450 500 550 600 650 700 750

Chlorophyll b

Chlorophyll a

Wavelength (nm)

Light and Pigments

• Chlorophyll does not absorb light well in the green region of the spectrum. Green light is reflected by leaves, which is why plants look green.

Est

imat

ed A

bso

rpti

on

(%

) 100

80

60

40

20

0400 450 500 550 600 650 700 750

Chlorophyll b

Chlorophyll a

Wavelength (nm)

Light and Pigments

• Light is a form of energy, so any compound that absorbs light also absorbs energy from that light.

• When chlorophyll absorbs light, much of the energy is transferred directly to electrons in the chlorophyll molecule, raising the energy levels of these electrons.

• These high-energy electrons are what make photosynthesis work.

The colors of light that are absorbed by chlorophylls are….

1 2 3 4

25% 25%25%25%

1. green and yellow.2. green, blue, and violet.3. blue, violet, and red.4. red and yellow.

8-2

– The colors of light that are absorbed by chlorophylls are

• green and yellow.• green, blue, and violet.• blue, violet, and red.• red and yellow.

REVIEW

• Let’s review section 8.2

In van Helmont's experiment, most of the added mass of the tree came from

1 2 3 4

25% 25%25%25%1.oil and carbon dioxide.2.water and carbon dioxide.3.oxygen and carbon dioxide.4.soil and oxygen.

Plants use the sugars produced in photosynthesis to make….

1 2 3 4

25% 25%25%25%

1. oxygen.2. starches.3. carbon dioxide.4. protein.

The raw materials required for plants to carry out photosynthesis are…

.

1 2 3 4

25% 25%25%25%

1. carbon dioxide and oxygen.2. oxygen and sugars.3. carbon dioxide and water.

4. oxygen and water..

The principal pigment in plants is….

1 2 3 4

25% 25%25%25%

1. chloroplast.2. chlorophyll.3. carotene.4. carbohydrate.

The colors of light that are absorbed by chlorophylls are….

1 2 3 4

25% 25%25%25%

1. green and yellow.2. green, blue, and violet.3. blue, violet, and red.4. red and yellow.

8-3 The Reactions of Photosynthesis

Inside a Chloroplast

• Inside a Chloroplast• In plants, photosynthesis takes place inside

chloroplasts.Plant

Plant cells

Chloroplast

In plants, photosynthesis takes place inside the….

1 2 3 4

25% 25%25%25%

1. thylakoids.2. chloroplasts.3. photosystems.4. chlorophyll.

8-3

– In plants, photosynthesis takes place inside the• thylakoids.• chloroplasts.• photosystems.• chlorophyll.


• Chloroplasts contain thylakoids—saclike photosynthetic membranes.

Chloroplast

Singlethylakoid


• Thylakoids are arranged in stacks known as grana. A singular stack is called a granum.

Granum

Chloroplast


• Proteins in the thylakoid membrane organize chlorophyll and other pigments into clusters called photosystems, which are the light-collecting units of the chloroplast.

Chloroplast

Photosystems

Energy to make ATP in the chloroplast comes most directly from

.

1 2 3 4

25% 25%25%25%

1. hydrogen ions flowing through an enzyme in the thylakoid membrane.

2. transfer of a phosphate from ADP.

3. electrons moving through the electron transport chain.

4. electrons transferred directly from NADPH.

8-3

– Energy to make ATP in the chloroplast comes most directly from

• hydrogen ions flowing through an enzyme in the thylakoid membrane.

• transfer of a phosphate from ADP.• electrons moving through the electron transport chain.

• electrons transferred directly from NADPH.

Chloroplast Diagram• Stroma = thick fluid

between the thylakoids

• thylakoids = disks within the chloroplasts

• granum=stack of thylakoids (grana pl.)

Inside a Chloroplast•The reactions of photosystems include: the light-dependent reactions and the light-independent reactions, or Calvin cycle.•The light-dependent reactions take place within the thylakoid membranes.•The Calvin cycle takes place in the stroma, which is the region outside the thylakoid membranes.

GRANA

• What is the difference between grana and granum?

STROMA

• So what’s the difference between the stoma and the stroma?

• STOMA = opening in lower epidermis• STROMA = area around thylakoid

disks in the chloroplast

Chloroplast DiagramStromal lamellaStromal lamella = connect grana= connect grana D. Outer MembraneD. Outer Membrane

Thylakoid Thylakoid membranemembrane

Thylakoid Thylakoid spacespaceIntermembrane Intermembrane

SpaceSpace

Inner Inner MembraneMembrane

Chloroplasts TEM

• Note the stacks of thylakoid disks =

grana• Note area between =

stroma


Chloroplast

Light

H2O

O2

CO2

Sugars

NADP+

ADP + P

Calvin Cycle

Light- dependent reactions

Calvin cycle

Electron Carriers

• Electron Carriers• When electrons in chlorophyll absorb sunlight, the

electrons gain a great deal of energy.• Cells use electron carriers to transport these high-

energy electrons from chlorophyll to other molecules.

THYLAKOIDS

Summary IN

Summary OUT

Electron Carriers

• One carrier molecule is NADP+.• Electron carriers, such as NADP+, transport electrons.• NADP+ accepts and holds 2 high-energy electrons along

with a hydrogen ion (H+). This converts the NADP+ into NADPH.

Nice Little Photosynthesis Movies

• VCAC: Cellular Processes: Photosynthesis: The Movie

• VCAC: Cellular Processes: Photosystem II: The Movie

http://vcell.ndsu.edu/animations/photosynthesis/movie.htm

http://vcell.ndsu.edu/animations/photosynthesis/movie.htm

http://vcell.ndsu.edu/animations/photosystemII/movie.htm

http://vcell.ndsu.edu/animations/photosystemII/movie.htm

Overview of Photosynthesis

What happens here?

• Light Dependent Reaction (LDR)

• Converts light energy to chemical energy + O2

• Light Independent Reaction (LIR)

• Assembles sugar molecules using CO2

Where does energy come from?

• Light Dependent Reaction LDR

• Uses light energy

• Light Independent Reaction LIR

• (Calvin Cycle)

• uses ATP and NADPH (from LDR)

PSI and PSII

• PSI and PSII animation

• Another PSI and PSII animation

http://www.cst.cmich.edu/users/baile1re/bio101fall/enzphoto/photoanima.htm

http://instruct1.cit.cornell.edu/Courses/biomi290/MOVIES/OXYGENIC.HTML

Where is it located in the cell?

• LDR• occurs in

thylakoid membranes of chloroplast’s grana

• LIR (aka Calvin cycle)

• occurs in stroma of chloroplast

Final Products of Each?

• LDR

• ATP and NADPH

• Also O2

• LIR

• sugar

Electron Carriers

• The conversion of NADP+ into NADPH is one way some of the energy of sunlight can be trapped in chemical form.

• The NADPH carries high-energy electrons to chemical reactions elsewhere in the cell.

• These high-energy electrons are used to help build a variety of molecules the cell needs, including carbohydrates like glucose.

Light-Dependent Reactions

– What happens in the light-dependent reactions?

Light-Dependent Reactions

• Light-Dependent Reactions» The light-dependent reactions require light. » The light-dependent reactions produce oxygen gas and

convert ADP and NADP+ into the energy carriers ATP and NADPH.

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8-1 Energy and Life Light-Dependent Reactions

of 20


Photosynthesis begins when pigments in photosystem II absorb light, increasing their energy level.

Photosystem II

of 20


These high-energy electrons are passed on to the electron transport chain.

Photosystem II

Electroncarriers

High-energy electron

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Enzymes on the thylakoid membrane break water molecules into:

Photosystem II

2H2O

Electroncarriers


of 20


• hydrogen ions

• oxygen atoms

• energized electrons

Photosystem II

2H2O

+ O2

Electroncarriers


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Photosystem II

2H2O

+ O2

The energized electrons from water replace the high-energy electrons that chlorophyll lost to the electron transport chain.


of 20


Photosystem II

2H2O

As plants remove electrons from water, oxygen is left behind and is released into the air.

+ O2


of 20


Photosystem II

2H2O

The hydrogen ions left behind when water is broken apart are released inside the thylakoid membrane.

+ O2


of 20


Photosystem II

2H2O

Energy from the electrons is used to transport H+ ions from the stroma into the inner thylakoid space.

+ O2

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Photosystem II

2H2O

High-energy electrons move through the electron transport chain from photosystem II to photosystem I.

+ O2

Photosystem I

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2H2O

Pigments in photosystem I use energy from light to re-energize the electrons.

+ O2

Photosystem I

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2H2O

NADP+ then picks up these high-energy electrons, along with H+ ions, and becomes NADPH.

+ O2

2 NADP+

2 NADPH2

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2H2O

As electrons are passed from chlorophyll to NADP+, more H+ ions are pumped across the membrane.

+ O2

2 NADP+

2 NADPH2

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2H2O

Soon, the inside of the membrane fills up with positively charged hydrogen ions, which makes the outside of the membrane negatively charged.

+ O2

2 NADP+

2 NADPH2

of 20


2H2O

The difference in charges across the membrane provides the energy to make ATP.

+ O2

2 NADP+

2 NADPH2

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2H2O

H+ ions cannot cross the membrane directly.

+ O2

ATP synthase

2 NADP+

2 NADPH2

of 20


2H2O

The cell membrane contains a protein called ATP synthase that allows H+ ions to pass through it.

+ O2

ATP synthase

2 NADP+

2 NADPH2

of 20


2H2O

As H+ ions pass through ATP synthase, the protein rotates.

+ O2

ATP synthase

2 NADP+

2 NADPH2

of 20


2H2O

As it rotates, ATP synthase binds ADP and a phosphate group together to produce ATP.

+ O2

2 NADP+

2 NADPH2

ATP synthase

ADP

of 20


2H2O

Because of this system, light-dependent electron transport produces not only high-energy electrons but ATP as well.

+ O2

ATP synthase

ADP2 NADP+

2 NADPH2

of 20


The light-dependent reactions use water, ADP, and NADP+.

The light-dependent reactions produce oxygen, ATP, and NADPH.

These compounds provide the energy to build energy-containing sugars from low-energy compounds.

NADPH is produced in light-dependent reactions and carries energy in the form of

.

1 2 3 4

25% 25%25%25%

1. ATP.2. high-energy electrons.3. low-energy electrons.4. ADP.

8-3

– NADPH is produced in light-dependent reactions and carries energy in the form of

• ATP.• high-energy electrons.• low-energy electrons.• ADP.

The Calvin Cycle

–

What is the Calvin cycle?

Calvin Cycle

• Occurs in stroma of chloroplasts

7.11 Review of Photosynthesis

Summary: Calvin Cycle

Overall Equation

The Calvin Cycle

• The Calvin Cycle • ATP and NADPH formed by the light-dependent

reactions contain an abundance of chemical energy, but they are not stable enough to store that energy for more than a few minutes.

• During the Calvin cycle plants use the energy that ATP and NADPH contain to build high-energy compounds that can be stored for a long time.

•

The Calvin Cycle» The Calvin cycle uses ATP and NADPH from the light-

dependent reactions to produce high-energy sugars.» Because the Calvin cycle does not require light, these

reactions are also called the light-independent reactions.

•

What is another name for the Calvin cycle?

.

1 2 3 4

25% 25%25%25%

1. light-dependent reactions2. light-independent reactions3. electron transport chain4. photosynthesis

8-3

– What is another name for the Calvin cycle?• light-dependent reactions• light-independent reactions• electron transport chain• photosynthesis

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8-1 Energy and Life The Calvin Cycle

Six carbon dioxide molecules enter the cycle from the atmosphere and combine with six 5-carbon molecules.

CO2 Enters the Cycle

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The result is twelve 3-carbon molecules, which are then converted into higher-energy forms.

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The energy for this conversion comes from ATP and high-energy electrons from NADPH.

12 NADPH

12

12 ADP

12 NADP+

Energy Input

of 20


Two of twelve 3-carbon molecules are removed from the cycle.

Energy Input

12 NADPH

12

12 ADP

12 NADP+

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The molecules are used to produce sugars, lipids, amino acids and other compounds.

12 NADPH

12

12 ADP

12 NADP+

6-Carbon sugar produced

Sugars and other compounds

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The 10 remaining 3-carbon molecules are converted back into six 5-carbon molecules, which are used to begin the next cycle.

12 NADPH

12

12 ADP

12 NADP+

5-Carbon MoleculesRegenerated

Sugars and other compounds

6

6 ADP

Which of the following factors does NOT directly affect photosynthesis?

.

1 2 3 4

25% 25%25%25%

1. wind2. water supply3. temperature4. light intensity

8-3

– Which of the following factors does NOT directly affect photosynthesis?

• wind• water supply• temperature• light intensity

The Calvin Cycle• The two sets of photosynthetic reactions work together.

– The light-dependent reactions trap sunlight energy in chemical form.

– The light-independent reactions use that chemical energy to produce stable, high-energy sugars from carbon dioxide and water.

Factors Affecting Photosynthesis

– Factors Affecting Photosynthesis • Many factors affect the rate of photosynthesis, including:

• Water• Temperature• Intensity of light

Which equation summarizes photosynthesis?

• A. water + starch ---> glucose + glucose + glucose B. water + carbon dioxide ---> oxygen + glucose + water C. glucose + oxygen ---> water + carbon dioxide + ATP D. glucose + glucose ---> maltose + water

ANSWER

• B. water + carbon dioxide ---> oxygen + glucose + water

In what organelle does photosynthesis occur?

• A. the nucleus B. chloroplasts C. the vacuole D. the cell wall

ANSWER

•B. Chloroplast

QUESTION:

• Four identical plants are grown under different colored light bulbs. Under which color will the release of oxygen gas be slowest? A. Green

• B. blue C. orange D. red

ANSWER:

•A. Green

QUIZ TIME

• The reason why ADP + P form ATP in thylakoid membranes is…

• A movement of electrons between photosystem II and photosystem I.

• B oxidation of water • C oxidation of NADPH • D absorption of photons by chloroplast pigments • E higher concentration of H+ inside versus outside

the thylakoid membranes

ANSWER

• E. a higher concentration of H+ ions inside vs. outside the thylakoid membranes

QUIZ TIME

• Water is broken down and the electrons from water pass through photosystem II and photosystem I before adding e- to:

• A carbon dioxide • B NADP+ • C plastoquinones • D FAD • E rubisco

ANSWER

• NADP+ to make higher energy NADPH

• REVIEW ALL OF CHAPTER 8

QUIZ TIME

• Which of the following would have the smallest effect on the rate of photosynthesis in a green plant? A. carbon dioxide concentration B. light intensity C. oxygen concentration D. water available

ANSWER:

• C. oxygen concentration

QUIZ TIME

• During photosynthetic electron transport, the interior compartment of the thylakoid membranes becomes:

• A. more concentrated with ATP• B. more concentrated with H+ ions• C. less concentrated with H+ ions

HINT: Distribution of H+ ions

• Light Rx• more inside

• Dark Rx• Even in and out

ANSWER

•More concentrated with H+ ions

QUIZ TIME

• Which of the following is produced during photosynthesis? A. carbon dioxide B. lactic acidC. DNA D. PGAL

•

ANSWER

•D. PGAL

QUIZ TIME

• Atmospheric oxygen that is inhaled by animals comes from: A. carbon dioxide molecules split during the light reactions B. carbon dioxide split during the dark reactions C. water molecules split during the light reactions D. water molecules split during the dark reactions

ANSWER

• C. water molecules split during the light reactions

QUIZ TIME

• What change occurs during photosynthesis? A. solar energy is converted to chemical energy B. kinetic energy is converted to chemical energy C. chemical energy is converted to radiant energy D. water is converted to chemical energy

ANSWER

• A. solar energy is converted to chemical energy

Cuticle Cuticle Epidermis Epidermis Guard cells Guard cells Palisade Palisade PhloemPhloemXylemXylemSpongy Spongy MesophyllMesophyllStomata Stomata Bundle Sheath Bundle Sheath

A=cuticleA=cuticle

B=Upper epidermisB=Upper epidermis

C=VeinC=Vein

D=PhloemD=Phloem

E=xylemE=xylem

F=Palisade layerF=Palisade layer

G=spongy layerG=spongy layer

H=guard cellH=guard cell

I=stomataI=stomata

QUIZ TIME

• The overall source of energy for photosynthesis is:

• A. energy from the sun• B. energy from ATP• C. energy when oxygen is produced

ANSWER

• A. energy from the sun

QUIZ TIME

• What three events occur during the light reactions of photosynthesis? –Forming ATP–NADP+ to NADPH–Fixing CO2

–Releasing O2

ANSWER

–Forming ATP–NADP+ to NADPH–Releasing O2

QUIZ TIME

• Which of the following does not happen in photosystem I?–ATP is produced–electron transport in the thylakoid

membranes– light energy is used–NADPH is formed

ANSWER (which is NOT)

• NADPH is formed

QUIZ TIME

• Where does the Calvin Cycle take place?–Thylakoid membranes of chloroplasts–Stroma of chloroplasts–Matrix of mitochondria–Inner membrane of mitochondria

ANSWER

• Stroma of chloroplasts

QUIZ TIME

• What is the name of the enzyme that causes CO2 to form glucose?–ATPase–glucosease–rubisco

ANSWER

• rubisco

QUIZ TIME

• What two high energy compounds are required for this reaction?–ATP–NADH–NADPH–ADP–FADH

ANSWER

• ATP and NADPH

QUIZ TIME

• What is the name of the process in which carbon dioxide is made into glucose?–Krebs cycle–Calvin cycle–Einstein cycle

ANSWER

• CALVIN CYCLE• (or sometimes the Calvin-Bensen

Cycle)

QUIZ TIME

• Which does NOT happen in the Dark Reaction:–using ATP–using NADPH–using Carbon Dioxide–making water

ANSWER

• MAKING WATER

QUIZ TIME

• What are the products of the dark reaction?–ATP–ADP–glucose–CO2

–NADP+

ANSWER

• ADP• NADP+• glucose

QUIZ TIME

• The reason why ADP + P form ATP in thylakoid membranes is…

A movement of electrons between photosystem II and photosystem I.

B oxidation of water C oxidation of NADPH D absorption of photons by chloroplast pigments E higher concentration of H+ inside versus outside the

thylakoid membranes

ANSWER

• a higher concentration of H+ ions inside vs. outside the thylakoid membranes