PHOTOSYNTHESIS
Using 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 energy is
used to make
sugar and other
food molecules
from carbon
dioxide and water
Chemical Reaction
sunlight
• 6 H2O + 6 CO2 ---------->
C6H12O6+ 6 O2
Photosynthesis: An
Overview of
Photosynthesis (click)
Photosynthetic Plants
Kelp (ocean)
Diatoms
(microscopic)
Forests
(land)
Leaf Structure
1. Stoma in leaf lower epidermis
• Is the opening
• carbon dioxide,
oxygen. And
water in/out
Stomata (pl.)
Leaf Cross section
2. Upper
Covers and protects
Epidermis
4. Mesophyllcells
containing
chloroplasts
3. Lower
epidermis
see stoma –in lower
epidermis only
4. Mesophyll
• = Palisade Layer + Spongy Layer
5. Cuticle
Waxy, waterproof
coating (to retain
H2O)
6. Palisade Layer
• cylindrical cells, vertically oriented,
closely packed
7. Spongy Layer
• cells are irregular in shape and
loosely packed
O2 ,CO2, H20 vapor
go 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?
9. Plant Vein: Xylem + Phloem
Xylem-(blue) carries
water
Phloem (thicker cell
wall)-(yellow)
carries 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)
Water Movement
• LINK:
http://www.sciencemag.org/sciext/vis2005/sh
ow/transpiration.swf
Elodea Cell 400X
Leaf cross section
Photosynthesis in Elodea Lab
See oxygen bubbles
coming from the Elodea
What conditions are best?
Elodea Bubbles Movie
• sLowlife Exhibit
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.autotrophs.
2.heterotrophs.
3.decomposers.
4.consumers.
25%
1
25%
25%
2
3
25%
4
8-1
– Organisms that make their own food are called
•
•
•
•
autotrophs.
heterotrophs.
decomposers.
consumers.
Most autotrophs obtain their energy from…..
1.chemicals in the environment. 25%
2. sunlight.
3. carbon dioxide in the air.
4. other producers.
1
25%
25%
2
3
25%
4
8-1
– Most autotrophs obtain their energy from
•
•
•
•
chemicals in the environment.
sunlight.
carbon dioxide in the air.
other producers.
Chemical Energy and ATP
• 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.
Chemical Energy and ATP
• ATP consists of:
– adenine
– ribose (a 5-carbon sugar)
– 3 phosphate groups
Adenine
ATP
Ribose
3 Phosphate groups
Chemical Energy and ATP
• 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.
ATP
ADP
+
Adenosine Diphosphate
(ADP) + Phosphate
Partially
charged
battery
Energy
Energy
Fully
charged
battery
Adenosine Triphosphate (ATP)
Chemical Energy and ATP
– Releasing Energy
• Energy stored in ATP is released by breaking the
chemical bond between the second and third
phosphates.
2 Phosphate groups
P
ADP
How is energy released from ATP?
1.
2.
3.
4.
A phosphate is added.
An adenine is added.
A phosphate is removed.
A ribose is removed
25%
1
25%
25%
2
3
25%
4
8-1
– How is energy released from ATP?
•
•
•
•
A phosphate is added.
An adenine is added.
A phosphate is removed.
A ribose is removed.
Chemical Energy and ATP
– 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.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.
25%
1
25%
25%
2
3
25%
4
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.much more energy.
2.much less energy.
3.about the same amount of
energy.
4.more energy sometimes and less
at others.
25%
1
25%
25%
2
3
25%
4
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.autotrophs.
2.heterotrophs.
3.decomposers.
4.consumers.
25%
1
25%
25%
2
3
25%
4
Most autotrophs obtain their
energy from…..
1.chemicals in the environment. 25%
2. sunlight.
3. carbon dioxide in the air.
4. other producers.
1
25%
25%
2
3
25%
4
How is energy released from
ATP?
….
1.
2.
3.
4.
A phosphate is added.
An adenine is added.
A phosphate is removed.
A ribose is removed
25%
1
25%
25%
2
3
25%
4
cells to function with only a
small amount of ATP?
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.
25%
1
25%
25%
2
3
25%
4
Compared to the energy stored in a molecule of glucose,
ATP stores
1.much more energy.
2.much less energy.
3.about the same amount of
energy.
4.more energy sometimes and less
at others.
25%
1
25%
25%
2
3
25%
4
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
• Investigating Photosynthesis
• Research into photosynthesis began centuries ago.
Investigating Photosynthesis
– 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.
Investigating Photosynthesis
• 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?
Investigating Photosynthesis
• 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.
Investigating Photosynthesis
– 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.
Investigating Photosynthesis
• 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.
Investigating Photosynthesis
– 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.
Investigating Photosynthesis
– 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 Photosynthesis Equation
• The equation for photosynthesis is:
• 6CO2 + 6H2O
Light
C6H12O6 + 6O2
• carbon dioxide + water
Light
sugars + oxygen
The Photosynthesis Equation
– 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. oxygen.
2. starches.
3. carbon dioxide.
25%
25%
25%
25%
4. protein.
1
2
3
4
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. carbon dioxide and oxygen.
2. oxygen and sugars.
3. carbon dioxide and water.
25%
25%
25%
2
3
25%
4. oxygen and water..
1
4
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.
8-1 Energy and Life
The Photosynthesis Equation
Light energy
O2
ADP
+
NADP
Sugar
CO2
+
H20
Slide
71 of 20
8-1 Energy and Life
Light and Pigments
What is the role of light and chlorophyll in
photosynthesis?
Slide
72 of 20
8-1 Energy and Life
Light and Pigments
Light and Pigments
How do plants capture the energy of sunlight?
In addition to water and carbon dioxide,
photosynthesis requires light and
chlorophyll.
Slide
73 of 20
8-1 Energy and Life
Light and Pigments
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
Slide
74 of 20
1.
2.
3.
4.
The principal pigment in plants is…
.
chloroplast.
chlorophyll.
carotene.
25%
25%
carbohydrate.
1
2
25%
3
25%
4
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
Wavelength
Chlorophyll b
• Absorbs: blue
and orange
• Reflects: yellowgreen
•An
accessory
chlorophyll
in plants
Other pigments in plants
Carotenoids-orange
• Absorb: bluegreen
• Reflect:
yellow-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)
Light and Pigments
Estimated Absorption (%)
• Chlorophyll absorbs light well in the blue-violet and red
regions of the visible spectrum.
100
80
60
Chlorophyll b
Chlorophyll a
40
20
0
(nm)
400 450 Wavelength
500 550 600
650 700 750
Wavelength (nm)
Light and Pigments
Estimated Absorption (%)
• 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.
100
80
60
Chlorophyll b
Chlorophyll a
40
20
0
400 450 500 550 600 650 700 750
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. green and yellow.
2. green, blue, and violet.
3. blue, violet, and red.
25%
25%
25%
25%
4. red and yellow.
1
2
3
4
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.oil and carbon dioxide.
2.water and carbon dioxide.
3.oxygen and carbon dioxide.
4.soil and oxygen.
25%
1
25%
25%
2
3
25%
4
Plants use the sugars produced in photosynthesis to make
….
1. oxygen.
2. starches.
3. carbon dioxide.
25%
25%
25%
25%
4. protein.
1
2
3
4
The raw materials required for plants to carry out
photosynthesis are…
.
1. carbon dioxide and oxygen.
2. oxygen and sugars.
3. carbon dioxide and water.
25%
25%
25%
2
3
25%
4. oxygen and water..
1
4
1.
2.
3.
4.
The principal pigment in plants is…
.
chloroplast.
chlorophyll.
carotene.
25%
25%
carbohydrate.
1
2
25%
3
25%
4
The colors of light that are absorbed by chlorophylls are…
.
1. green and yellow.
2. green, blue, and violet.
3. blue, violet, and red.
25%
25%
25%
25%
4. red and yellow.
1
2
3
4
8-3 The Reactions of
Photosynthesis
Inside a Chloroplast
• Inside a Chloroplast
• In plants, photosynthesis takes place inside
chloroplasts.
Plant
Chloroplast
Plant cells
1.
2.
3.
4.
In plants, photosynthesis takes place inside the
…
.
thylakoids.
chloroplasts.
photosystems.
25%
25%
25%
chlorophyll.
1
2
3
25%
4
8-3
– In plants, photosynthesis takes place inside the
•
•
•
•
thylakoids.
chloroplasts.
photosystems.
chlorophyll.
Inside a Chloroplast
• Chloroplasts contain thylakoids—saclike photosynthetic
membranes.
Single
thylakoid
Chloroplast
Inside a Chloroplast
• Thylakoids are arranged in stacks known as grana. A
singular stack is called a granum.
Granum
Chloroplast
Inside a Chloroplast
• Proteins in the thylakoid membrane organize
chlorophyll and other pigments into clusters called
photosystems, which are the light-collecting units of
the chloroplast.
Photosystems
Chloroplast
Energy to make ATP in the chloroplast comes most directly
from
.
1. hydrogen ions flowing through an
enzyme in the thylakoid
membrane.
25%
25%
25%
25%
2. transfer of a phosphate from ADP.
3. electrons moving through the
electron transport chain.
4. electrons transferred directly from
NADPH.
1
2
3
4
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 lightindependent 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 Diagram
Stromal lamella
D.
Outer
Membrane
= connect grana
Thylakoid
membrane
Inner
Membrane
Intermembrane
Space
Thylakoid
space
Chloroplasts TEM
• Note the stacks of
thylakoid disks =
grana
• Note area between =
stroma
H O a Chloroplast
CO
Inside
2
Light
2
NADP+
ADP + P
Lightdependent
reactions
Calvin
Calvin
cycle
Cycle
Chloroplast
O2
Sugars
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 highenergy 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
Overview of Photosynthesis
What happens here?
• Light Dependent
Reaction (LDR)
• Light Independent
Reaction (LIR)
• Converts light
• Assembles sugar
energy to
molecules using
chemical energy +
CO2
O2
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
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
• LIR
• ATP and
NADPH
• Also O2
• 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.
8-1 Energy and Life
Light-Dependent Reactions
Slide
125 of 20
8-1 Energy and Life
Light-Dependent Reactions
Photosynthesis begins when pigments in
photosystem II absorb light, increasing their
energy level.
Photosystem II
Slide
126 of 20
8-1 Energy and Life
Light-Dependent Reactions
These high-energy electrons are passed on to the
electron transport chain.
Photosystem II
High-energy
electron
Electron
carriers
Slide
127 of 20
8-1 Energy and Life
Light-Dependent Reactions
Enzymes on the thylakoid membrane break water
molecules into:
Photosystem II
2H2O
High-energy
electron
Electron
carriers
Slide
128 of 20
8-1 Energy and Life
Light-Dependent Reactions
• hydrogen ions
• oxygen atoms
• energized electrons
Photosystem II
+
O2
2H2O
High-energy
electron
Electron
carriers
Slide
129 of 20
8-1 Energy and Life
Light-Dependent Reactions
The energized electrons from water replace the
high-energy electrons that chlorophyll lost to the
electron transport chain.
Photosystem II
+
O2
2H2O
High-energy
electron
Slide
130 of 20
8-1 Energy and Life
Light-Dependent Reactions
As plants remove electrons from water, oxygen is
left behind and is released into the air.
Photosystem II
+
O2
2H2O
High-energy
electron
Slide
131 of 20
8-1 Energy and Life
Light-Dependent Reactions
The hydrogen ions left behind when water is broken
apart are released inside the thylakoid membrane.
Photosystem II
+
O2
2H2O
High-energy
electron
Slide
132 of 20
8-1 Energy and Life
Light-Dependent Reactions
Energy from the electrons is used to transport H+
ions from the stroma into the inner thylakoid space.
Photosystem II
+
O2
2H2O
Slide
133 of 20
8-1 Energy and Life
Light-Dependent Reactions
High-energy electrons move through the electron
transport chain from photosystem II to
photosystem I.
Photosystem II
+
O2
2H2O
Photosystem I
Slide
134 of 20
8-1 Energy and Life
Light-Dependent Reactions
Pigments in photosystem I use energy from
light to re-energize the electrons.
+
O2
2H2O
Photosystem I
Slide
135 of 20
8-1 Energy and Life
Light-Dependent Reactions
NADP+ then picks up these high-energy electrons,
along with H+ ions, and becomes NADPH.
+
O2
2H2O
2 NADP+
2
2
NADPH
Slide
136 of 20
8-1 Energy and Life
Light-Dependent Reactions
As electrons are passed from chlorophyll to
NADP+, more H+ ions are pumped across the
membrane.
+
O2
2H2O
2 NADP+
2
2
NADPH
Slide
137 of 20
8-1 Energy and Life
Light-Dependent Reactions
Soon, the inside of the membrane fills up with
positively charged hydrogen ions, which makes
the outside of the membrane negatively charged.
+
O2
2H2O
2 NADP+
2
2
NADPH
Slide
138 of 20
8-1 Energy and Life
Light-Dependent Reactions
The difference in charges across the membrane
provides the energy to make ATP.
+
O2
2H2O
2 NADP+
2
2
NADPH
Slide
139 of 20
8-1 Energy and Life
Light-Dependent Reactions
H+ ions cannot cross the membrane directly.
ATP synthase
+
O2
2H2O
2 NADP+
2
2
NADPH
Slide
140 of 20
8-1 Energy and Life
Light-Dependent Reactions
The cell membrane contains a protein called ATP
synthase that allows H+ ions to pass through it.
ATP synthase
+
O2
2H2O
2 NADP+
2
2
NADPH
Slide
141 of 20
8-1 Energy and Life
Light-Dependent Reactions
As H+ ions pass through ATP synthase, the
protein rotates.
ATP synthase
+
O2
2H2O
2 NADP+
2
2
NADPH
Slide
142 of 20
8-1 Energy and Life
Light-Dependent Reactions
As it rotates, ATP synthase binds ADP and a
phosphate group together to produce ATP.
ATP synthase
+
O2
2H2O
ADP
2 NADP+
2
2
NADPH
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8-1 Energy and Life
Light-Dependent Reactions
Because of this system, light-dependent electron
transport produces not only high-energy electrons
but ATP as well.
ATP synthase
+
O2
2H2O
ADP
2 NADP+
2
2
NADPH
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8-1 Energy and Life
Light-Dependent Reactions
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 lowenergy compounds.
Slide
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NADPH is produced in light-dependent reactions and carries
energy in the form of
1.
2.
3.
4.
ATP.
high-energy electrons.
low-energy electrons.
ADP.
.
25%
1
25%
25%
2
3
25%
4
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 lightdependent 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.
light-dependent reactions
light-independent reactions
electron transport chain
photosynthesis
.
25%
1
25%
25%
2
3
25%
4
8-3
– What is another name for the Calvin cycle?
•
•
•
•
light-dependent reactions
light-independent reactions
electron transport chain
photosynthesis
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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8-1 Energy and Life
The Calvin Cycle
The result is twelve 3-carbon molecules, which
are then converted into higher-energy forms.
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8-1 Energy and Life
The Calvin Cycle
The energy for this conversion comes from ATP
and high-energy electrons from NADPH.
Energy Input
12
12 ADP
12 NADPH
12 NADP+
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8-1 Energy and Life
The Calvin Cycle
Two of twelve 3-carbon molecules are removed
from the cycle.
Energy Input
12
12 ADP
12 NADPH
12 NADP+
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8-1 Energy and Life
The Calvin Cycle
The molecules are used to produce sugars, lipids,
amino acids and other compounds.
12
12 ADP
12 NADPH
12 NADP+
6-Carbon sugar
produced
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Sugars and other compounds
8-1 Energy and Life
The Calvin Cycle
The 10 remaining 3-carbon molecules are
converted back into six 5-carbon molecules,
which are used to begin the next cycle.
12
12 ADP
6 ADP
12 NADPH
6
12 NADP+
5-Carbon Molecules
Regenerated
Slide
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Sugars and other compounds
Which of the following factors does NOT directly affect
photosynthesis?
1.
2.
3.
4.
wind
water supply
temperature
light intensity
.
25%
1
25%
25%
2
3
25%
4
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.
B.
C.
D.
the nucleus
chloroplasts
the vacuole
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 acid
C. 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
Epidermis
Guard cells
Palisade
Phloem
Xylem
Spongy
Mesophyll
Stomata
Bundle Sheath
A=cuticle
B=Upper epidermis
C=Vein
D=Phloem
E=xylem
F=Palisade layer
G=spongy layer
H=guard cell
I=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
HINT
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
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
ANSWER
• More concentrated with H+ ions
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
• 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)
8-1
– Organisms that make their own food are called
•
•
•
•
autotrophs.
heterotrophs.
decomposers.
consumers.
8-1
– Most autotrophs obtain their energy from
•
•
•
•
chemicals in the environment.
sunlight.
carbon dioxide in the air.
other producers.
8-1
– How is energy released from ATP?
•
•
•
•
A phosphate is added.
An adenine is added.
A phosphate is removed.
A ribose is removed.
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.
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.
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.
8-2
– Plants use the sugars produced in photosynthesis
to make
•
•
•
•
oxygen.
starches.
carbon dioxide.
protein.
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.
8-2
– The principal pigment in plants is
•
•
•
•
chloroplast.
chlorophyll.
carotene.
carbohydrate.
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.
8-3
– In plants, photosynthesis takes place inside the
•
•
•
•
thylakoids.
chloroplasts.
photosystems.
chlorophyll.
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.
8-3
– NADPH is produced in light-dependent reactions
and carries energy in the form of
•
•
•
•
ATP.
high-energy electrons.
low-energy electrons.
ADP.
8-3
– What is another name for the Calvin cycle?
•
•
•
•
light-dependent reactions
light-independent reactions
electron transport chain
photosynthesis
8-3
– Which of the following factors does NOT directly
affect photosynthesis?
•
•
•
•
wind
water supply
temperature
light intensity