Cellular Energy
chapter
8
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
-!). )DEA
Light energy is tr

Light Reactions of Photosynthesis : Light reactions of photosynthesis occur in the thylakoid membranes, where light energy is converted into chemical energy in the form of ATP and NADPH, and oxygen is released as a byproduct.

Photosynthesis equation : The chemical equation for photosynthesis is 6CO2 + 6H2O → C6H12O6 + 6O2, showing how carbon dioxide and water are converted into glucose and oxygen using light energy, primarily within the chloroplasts of plant cells.

Photosynthesis involves photosystems and electron transport : Photosystem I and II are made of light-absorbing pigments and proteins crucial for light reactions, facilitating electron movement and energy transfer in photosynthesis.

apped and

Light Reactions of Photosynthesis : Light reactions of photosynthesis occur in the thylakoid membranes, where light energy is converted into chemical energy in the form of ATP and NADPH, and oxygen is released as a byproduct.

Photosynthesis equation : The chemical equation for photosynthesis is 6CO2 + 6H2O → C6H12O6 + 6O2, showing how carbon dioxide and water are converted into glucose and oxygen using light energy, primarily within the chloroplasts of plant cells.

Photosynthesis involves photosystems and electron transport : Photosystem I and II are made of light-absorbing pigments and proteins crucial for light reactions, facilitating electron movement and energy transfer in photosynthesis.

con

Light Reactions of Photosynthesis : Light reactions of photosynthesis occur in the thylakoid membranes, where light energy is converted into chemical energy in the form of ATP and NADPH, and oxygen is released as a byproduct.

Photosynthesis equation : The chemical equation for photosynthesis is 6CO2 + 6H2O → C6H12O6 + 6O2, showing how carbon dioxide and water are converted into glucose and oxygen using light energy, primarily within the chloroplasts of plant cells.

Photosynthesis involves photosystems and electron transport : Photosystem I and II are made of light-absorbing pigments and proteins crucial for light reactions, facilitating electron movement and energy transfer in photosynthesis.

verted into chemical energy

Light Reactions of Photosynthesis : Light reactions of photosynthesis occur in the thylakoid membranes, where light energy is converted into chemical energy in the form of ATP and NADPH, and oxygen is released as a byproduct.

Photosynthesis equation : The chemical equation for photosynthesis is 6CO2 + 6H2O → C6H12O6 + 6O2, showing how carbon dioxide and water are converted into glucose and oxygen using light energy, primarily within the chloroplasts of plant cells.

Photosynthesis involves photosystems and electron transport : Photosystem I and II are made of light-absorbing pigments and proteins crucial for light reactions, facilitating electron movement and energy transfer in photosynthesis.

during photosynthesis

Light Reactions of Photosynthesis : Light reactions of photosynthesis occur in the thylakoid membranes, where light energy is converted into chemical energy in the form of ATP and NADPH, and oxygen is released as a byproduct.

Photosynthesis equation : The chemical equation for photosynthesis is 6CO2 + 6H2O → C6H12O6 + 6O2, showing how carbon dioxide and water are converted into glucose and oxygen using light energy, primarily within the chloroplasts of plant cells.

Photosynthesis involves photosystems and electron transport : Photosystem I and II are made of light-absorbing pigments and proteins crucial for light reactions, facilitating electron movement and energy transfer in photosynthesis.

.
What You’ll Learn
the two phases of phot

Phases of photosynthesis : Photosynthesis occurs in two phases: light-dependent reactions, converting light energy into chemical energy as ATP and NADPH, and light-independent reactions, using these to form glucose.

osynthesis

Phases of photosynthesis : Photosynthesis occurs in two phases: light-dependent reactions, converting light energy into chemical energy as ATP and NADPH, and light-independent reactions, using these to form glucose.

how a chlor

chloroplasts : Organelles found in plant cells and other photosynthetic organisms responsible for capturing light energy and converting it into chemical energy through photosynthesis.

oplas

chloroplasts : Organelles found in plant cells and other photosynthetic organisms responsible for capturing light energy and converting it into chemical energy through photosynthesis.

t works during
light reactions
how electron transport works
Before You Read
Plants change energy from sunlight into energy that is used by
other living things. Describe on the lines below what would
happen to life on Earth if plants suddenly disappeared. Then
read about how plants use the Suns energy.
Identify Details As you
read, highlight or underline
the events of each stage of

Photosynthesis equation : The chemical equation for photosynthesis is 6CO2 + 6H2O → C6H12O6 + 6O2, showing how carbon dioxide and water are converted into glucose and oxygen using light energy, primarily within the chloroplasts of plant cells.

Phases of photosynthesis : Photosynthesis occurs in two phases: light-dependent reactions, converting light energy into chemical energy as ATP and NADPH, and light-independent reactions, using these to form glucose.

photosynthesis

Photosynthesis equation : The chemical equation for photosynthesis is 6CO2 + 6H2O → C6H12O6 + 6O2, showing how carbon dioxide and water are converted into glucose and oxygen using light energy, primarily within the chloroplasts of plant cells.

Phases of photosynthesis : Photosynthesis occurs in two phases: light-dependent reactions, converting light energy into chemical energy as ATP and NADPH, and light-independent reactions, using these to form glucose.

.
1. Identify one way cells
can use glucose.
section Photosynthesi

Light Reactions of Photosynthesis : Light reactions of photosynthesis occur in the thylakoid membranes, where light energy is converted into chemical energy in the form of ATP and NADPH, and oxygen is released as a byproduct.

Photosynthesis involves photosystems and electron transport : Photosystem I and II are made of light-absorbing pigments and proteins crucial for light reactions, facilitating electron movement and energy transfer in photosynthesis.

s
2
Read to Learn
Overview of Photosynthesis
Photosynthesis is the process in which light energy from
the Sun is changed into chemical energy. Nearly all life on
Earth depends on photosynthesis. The chemical equation for
photosynthesis is shown below.
6CO2 6H2O C
6H12O6 6O2
Photosynthesis occurs in two phases. In phase one—th

atp : A molecule that acts as an energy carrier in cells, storing and supplying energy needed for various metabolic processes.

ATP is made during photosynthesis when light energy causes water molecules to split : Light energy splits water into oxygen and hydrogen ions, where protons move through ATP synthase channels, forming ATP.

e
light-dependent reactions

Light-dependent Reactions : The light-dependent reactions are the first phase of photosynthesis where light energy is absorbed by chlorophyll and converted into chemical energy in the form of ATP and NADPH.

—light energy is absorbed and

atp : A molecule that acts as an energy carrier in cells, storing and supplying energy needed for various metabolic processes.

ATP is made during photosynthesis when light energy causes water molecules to split : Light energy splits water into oxygen and hydrogen ions, where protons move through ATP synthase channels, forming ATP.

changed into c

atp : A molecule that acts as an energy carrier in cells, storing and supplying energy needed for various metabolic processes.

ATP is made during photosynthesis when light energy causes water molecules to split : Light energy splits water into oxygen and hydrogen ions, where protons move through ATP synthase channels, forming ATP.

hemical energ

atp : A molecule that acts as an energy carrier in cells, storing and supplying energy needed for various metabolic processes.

ATP is made during photosynthesis when light energy causes water molecules to split : Light energy splits water into oxygen and hydrogen ions, where protons move through ATP synthase channels, forming ATP.

y in the form of

atp : A molecule that acts as an energy carrier in cells, storing and supplying energy needed for various metabolic processes.

ATP is made during photosynthesis when light energy causes water molecules to split : Light energy splits water into oxygen and hydrogen ions, where protons move through ATP synthase channels, forming ATP.

ATP and
NADPH.

nadph : An energy-rich molecule that carries electrons and is used in the synthesis of carbohydrates in photosynthesis.

NADP+ : A coenzyme that acts as an electron carrier, becoming NADPH in its reduced form, used in the Calvin cycle to help convert carbon dioxide into glucose.

In phase two—the light-independent reactions

Light-independent Reactions : Also known as the Calvin Cycle, the light-independent reactions occur in the stroma of chloroplasts, using the ATP and NADPH produced in the light-dependent reactions to synthesize glucose.

—the ATP
and NADPH that were formed in phase one are used to
make glucose. Glucose can then be joined with other simple
sugars to form larger molecules such as complex sugars
and carbohydrates. Sugar can also be changed into other
molecules needed by the cell, such as proteins, lipids, and
nucleic acids.
light
86
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Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Phase One: Light Reactions

Light-dependent Reactions : The light-dependent reactions are the first phase of photosynthesis where light energy is absorbed by chlorophyll and converted into chemical energy in the form of ATP and NADPH.

Light-independent Reactions : Also known as the Calvin Cycle, the light-independent reactions occur in the stroma of chloroplasts, using the ATP and NADPH produced in the light-dependent reactions to synthesize glucose.

Plants hav

chloroplasts : Organelles found in plant cells and other photosynthetic organisms responsible for capturing light energy and converting it into chemical energy through photosynthesis.

e special organelles called chloroplas

chloroplasts : Organelles found in plant cells and other photosynthetic organisms responsible for capturing light energy and converting it into chemical energy through photosynthesis.

ts to
capture light energy. Photosynthesi

Light Reactions of Photosynthesis : Light reactions of photosynthesis occur in the thylakoid membranes, where light energy is converted into chemical energy in the form of ATP and NADPH, and oxygen is released as a byproduct.

Photosynthesis equation : The chemical equation for photosynthesis is 6CO2 + 6H2O → C6H12O6 + 6O2, showing how carbon dioxide and water are converted into glucose and oxygen using light energy, primarily within the chloroplasts of plant cells.

Phases of photosynthesis : Photosynthesis occurs in two phases: light-dependent reactions, converting light energy into chemical energy as ATP and NADPH, and light-independent reactions, using these to form glucose.

Photosynthesis involves photosystems and electron transport : Photosystem I and II are made of light-absorbing pigments and proteins crucial for light reactions, facilitating electron movement and energy transfer in photosynthesis.

s begins when sunlight
is captured. The captured energy is stored in two energy
storage molecules—ATP and NADPH—that will be used
in light-independent reactions.
What happens in chloroplasts?
Chloroplasts are large organelles that capture light
energy from the Sun. They are found in plants and other
photosynthetic organisms. The fi gure below shows
a chloroplast.
A chloroplast is a disc-shaped organelle that contains two
compartments. Thylakoids (THI la koyds) are fl attened

thylakoids : Flattened saclike membranes within chloroplasts where the light-dependent reactions of photosynthesis take place.

Thylakoid Membrane : The site within the chloroplast where the light-dependent reactions of photosynthesis occur, containing photosystems I and II.

saclike membranes.

thylakoids : Flattened saclike membranes within chloroplasts where the light-dependent reactions of photosynthesis take place.

Thylakoid Membrane : The site within the chloroplast where the light-dependent reactions of photosynthesis occur, containing photosystems I and II.

The thylakoids are arranged in stacks
called gran

grana : Stacks of thylakoids within the chloroplasts where light reactions occur.

a. The fl uid-fi lled space outside the grana is the
strom

stroma : A fluid-filled space in chloroplasts surrounding the grana where light-independent reactions of photosynthesis occur.

a. Phase one takes place in the thylakoids. Phase two
takes place in the stroma.
2. Name Which organism
has chloroplasts

chloroplasts : Organelles found in plant cells and other photosynthetic organisms responsible for capturing light energy and converting it into chemical energy through photosynthesis.

? (Circle
your answer.)
a. mushroom
b. oak tree
c. earthworm
Picture This
3. Illustrate In the box,
draw an enlarged picture
of a granum

Granum : A granum is a stack of thylakoids within the chloroplasts where the light-dependent reactions of photosynthesis occur.

.
4. Explain Why do the
leaves of some trees
change colors in autumn

Changing leaf color in autumn : In autumn, the breakdown of chlorophyll reveals other pigments, such as carotenoids, resulting in leaves changing color to red, yellow, or orange.

?
Gran

grana : Stacks of thylakoids within the chloroplasts where light reactions occur.

um
Thylakoid

thylakoids : Flattened saclike membranes within chloroplasts where the light-dependent reactions of photosynthesis take place.

Thylakoid Membrane : The site within the chloroplast where the light-dependent reactions of photosynthesis occur, containing photosystems I and II.

Location of
phase one
Strom

stroma : A fluid-filled space in chloroplasts surrounding the grana where light-independent reactions of photosynthesis occur.

a—
location of
phase two
Outer
membrane
Inner
membrane
Chloroplas

chloroplasts : Organelles found in plant cells and other photosynthetic organisms responsible for capturing light energy and converting it into chemical energy through photosynthesis.

chlorophylls : The primary light-absorbing pigments in plants that capture light energy for photosynthesis, giving plants their green color.

t
What is the role of pigments in photosynthesis

Photosynthesis equation : The chemical equation for photosynthesis is 6CO2 + 6H2O → C6H12O6 + 6O2, showing how carbon dioxide and water are converted into glucose and oxygen using light energy, primarily within the chloroplasts of plant cells.

Phases of photosynthesis : Photosynthesis occurs in two phases: light-dependent reactions, converting light energy into chemical energy as ATP and NADPH, and light-independent reactions, using these to form glucose.

?
Thylakoids contain light-absorbing color

thylakoids : Flattened saclike membranes within chloroplasts where the light-dependent reactions of photosynthesis take place.

ed molecules known
as pigments. Different pigments absorb different wavelengths
of light. Chlorophylls are the major light-absorbing pigments
in plants. They absorb energy from violet-blue light and refl ect
green light, giving plants their green color.
Accessory pigments help plants absorb additional light.
For instance, carotenoid

carotenoids : Accessory pigments in plants that absorb blue and green light and reflect yellow, orange, and red, contributing to the colors seen in leaves during autumn.

s (kuh ROH tuh noyds) absorb blue
and green light and refl ect yellow, orange, and red light.
Carotenoids give carrots and sweet potatoes their orange color

Changing leaf color in autumn : In autumn, the breakdown of chlorophyll reveals other pigments, such as carotenoids, resulting in leaves changing color to red, yellow, or orange.

.
Accessory pigments are the reason leaves change colors in

Changing leaf color in autumn : In autumn, the breakdown of chlorophyll reveals other pigments, such as carotenoids, resulting in leaves changing color to red, yellow, or orange.

autumn

Changing leaf color in autumn : In autumn, the breakdown of chlorophyll reveals other pigments, such as carotenoids, resulting in leaves changing color to red, yellow, or orange.

. In green leaves, there is so much chloro

chlorophylls : The primary light-absorbing pigments in plants that capture light energy for photosynthesis, giving plants their green color.

phyll that it
masks the other pigments. In autumn, as trees prepare to lose
their leaves, the chlorophyll molecules break down, revealing
the colors of other pigments. The colors red, yellow, and
orange can be seen.
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Chapter 8 Cellular Energy Reading Essentials
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
How does electron transport work?
Photosystem I and phot

Photosystem I and Photosystem II : Photosystem I and Photosystem II are complexes of proteins and pigments in the thylakoid membrane crucial for the light-dependent reactions of photosynthesis. They absorb light energy and facilitate the transport of electrons through electron transport chains.

osystem II

Photosystem I and Photosystem II : Photosystem I and Photosystem II are complexes of proteins and pigments in the thylakoid membrane crucial for the light-dependent reactions of photosynthesis. They absorb light energy and facilitate the transport of electrons through electron transport chains.

are made of pigmen

Pigment : Pigments are light-absorbing colored molecules found in the thylakoid membranes of chloroplasts. They capture different wavelengths of light, with chlorophyll being the primary pigment that absorbs violet-blue light and reflects green.

ts
that absorb light and proteins that are important in light
reactions. They are in the thylak

thylakoids : Flattened saclike membranes within chloroplasts where the light-dependent reactions of photosynthesis take place.

Thylakoid Membrane : The site within the chloroplast where the light-dependent reactions of photosynthesis occur, containing photosystems I and II.

oid membrane

thylakoids : Flattened saclike membranes within chloroplasts where the light-dependent reactions of photosynthesis take place.

Thylakoid Membrane : The site within the chloroplast where the light-dependent reactions of photosynthesis occur, containing photosystems I and II.

. Follow
along in the fi gure below as you read about their role in
photosynthesis

Photosynthesis equation : The chemical equation for photosynthesis is 6CO2 + 6H2O → C6H12O6 + 6O2, showing how carbon dioxide and water are converted into glucose and oxygen using light energy, primarily within the chloroplasts of plant cells.

.
Photosynthesis begins when light energ

Light Reactions of Photosynthesis : Light reactions of photosynthesis occur in the thylakoid membranes, where light energy is converted into chemical energy in the form of ATP and NADPH, and oxygen is released as a byproduct.

Phases of photosynthesis : Photosynthesis occurs in two phases: light-dependent reactions, converting light energy into chemical energy as ATP and NADPH, and light-independent reactions, using these to form glucose.

Photosynthesis involves photosystems and electron transport : Photosystem I and II are made of light-absorbing pigments and proteins crucial for light reactions, facilitating electron movement and energy transfer in photosynthesis.

y causes electrons in

Light Reactions of Photosynthesis : Light reactions of photosynthesis occur in the thylakoid membranes, where light energy is converted into chemical energy in the form of ATP and NADPH, and oxygen is released as a byproduct.

Phases of photosynthesis : Photosynthesis occurs in two phases: light-dependent reactions, converting light energy into chemical energy as ATP and NADPH, and light-independent reactions, using these to form glucose.

Photosynthesis involves photosystems and electron transport : Photosystem I and II are made of light-absorbing pigments and proteins crucial for light reactions, facilitating electron movement and energy transfer in photosynthesis.

photosystem

Light Reactions of Photosynthesis : Light reactions of photosynthesis occur in the thylakoid membranes, where light energy is converted into chemical energy in the form of ATP and NADPH, and oxygen is released as a byproduct.

Phases of photosynthesis : Photosynthesis occurs in two phases: light-dependent reactions, converting light energy into chemical energy as ATP and NADPH, and light-independent reactions, using these to form glucose.

Photosynthesis involves photosystems and electron transport : Photosystem I and II are made of light-absorbing pigments and proteins crucial for light reactions, facilitating electron movement and energy transfer in photosynthesis.

II to go into a high energy state. The light ener

ATP is made during photosynthesis when light energy causes water molecules to split : Light energy splits water into oxygen and hydrogen ions, where protons move through ATP synthase channels, forming ATP.

gy

ATP is made during photosynthesis when light energy causes water molecules to split : Light energy splits water into oxygen and hydrogen ions, where protons move through ATP synthase channels, forming ATP.

also causes a water molecule to split, releasing an electron

ATP is made during photosynthesis when light energy causes water molecules to split : Light energy splits water into oxygen and hydrogen ions, where protons move through ATP synthase channels, forming ATP.

into the electron transport system, a hydrogen ion into the
thylakoid space, and oxygen as a waste product. The excited
electrons move from photosystem II and move along a series
of electron-carriers to photosystem I. Photosystem I absorbs
more light, and the excited electrons move along electron-
carriers again. Finally, the electrons are moved to NADP

nadph : An energy-rich molecule that carries electrons and is used in the synthesis of carbohydrates in photosynthesis.

,
forming the energy-storage molecule NADPH.
How is ATP made during photosynthesis?
ATP is made when light energy causes the water molecule
to split into oxygen and two hydrogen ions (H), or protons.
Protons build up inside the thylak

Thylakoid Membrane : The site within the chloroplast where the light-dependent reactions of photosynthesis occur, containing photosystems I and II.

oid

Thylakoid Membrane : The site within the chloroplast where the light-dependent reactions of photosynthesis occur, containing photosystems I and II.

. Protons diffuse through
ion channels into the str

stroma : A fluid-filled space in chloroplasts surrounding the grana where light-independent reactions of photosynthesis occur.

oma where the concentration is lower.
These channels are enzymes called ATP synthases.

ATP Synthase : ATP synthase is an enzyme located in the thylakoid membrane that catalyzes the formation of ATP from ADP and inorganic phosphate, powered by the flow of protons through its channel.

As protons
move into the stroma, ATP is formed.
5. Describe Of what
are photosystem I and

Photosystem I and Photosystem II : Photosystem I and Photosystem II are complexes of proteins and pigments in the thylakoid membrane crucial for the light-dependent reactions of photosynthesis. They absorb light energy and facilitate the transport of electrons through electron transport chains.

photosystem II

Photosystem I and Photosystem II : Photosystem I and Photosystem II are complexes of proteins and pigments in the thylakoid membrane crucial for the light-dependent reactions of photosynthesis. They absorb light energy and facilitate the transport of electrons through electron transport chains.

made?
Picture This
6. Identify On the fi gure,
highlight the path that
electrons follow. What
molecule is the electrons
nal destination?
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Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Phase Two: The Calvin Cycle

Calvin Cycle : The Calvin Cycle is a series of light-independent reactions in photosynthesis where atmospheric CO2 and energy stored in ATP and NADPH are used to synthesize glucose and other sugars.

NADPH and A

nadph : An energy-rich molecule that carries electrons and is used in the synthesis of carbohydrates in photosynthesis.

TP are temporary storage molecules. During
phase two, also known as the Calv

Calvin cycle stores energy in organic molecules : The Calvin cycle, also known as light-independent reactions, uses ATP and NADPH to convert carbon dioxide into sugars without the need for sunlight.

in cy

Calvin cycle stores energy in organic molecules : The Calvin cycle, also known as light-independent reactions, uses ATP and NADPH to convert carbon dioxide into sugars without the need for sunlight.

cle

Calvin cycle stores energy in organic molecules : The Calvin cycle, also known as light-independent reactions, uses ATP and NADPH to convert carbon dioxide into sugars without the need for sunlight.

, the ener

Calvin cycle stores energy in organic molecules : The Calvin cycle, also known as light-independent reactions, uses ATP and NADPH to convert carbon dioxide into sugars without the need for sunlight.

gy in these

Calvin cycle stores energy in organic molecules : The Calvin cycle, also known as light-independent reactions, uses ATP and NADPH to convert carbon dioxide into sugars without the need for sunlight.

molecules is stor

Calvin cycle stores energy in organic molecules : The Calvin cycle, also known as light-independent reactions, uses ATP and NADPH to convert carbon dioxide into sugars without the need for sunlight.

ed in organic

Calvin cycle stores energy in organic molecules : The Calvin cycle, also known as light-independent reactions, uses ATP and NADPH to convert carbon dioxide into sugars without the need for sunlight.

molecules, such as glucose.
What happens in the Calvin cycle?
The Calvin cycle builds sugars out of carbon dioxide and
water using the energy stored in ATP and NADPH. The Calvin
cycles reactions do not r

Light-independent Reactions : Also known as the Calvin Cycle, the light-independent reactions occur in the stroma of chloroplasts, using the ATP and NADPH produced in the light-dependent reactions to synthesize glucose.

equire sunlight,

Light-independent Reactions : Also known as the Calvin Cycle, the light-independent reactions occur in the stroma of chloroplasts, using the ATP and NADPH produced in the light-dependent reactions to synthesize glucose.

which is why they ar

Light-independent Reactions : Also known as the Calvin Cycle, the light-independent reactions occur in the stroma of chloroplasts, using the ATP and NADPH produced in the light-dependent reactions to synthesize glucose.

e
also referred t

Light-independent Reactions : Also known as the Calvin Cycle, the light-independent reactions occur in the stroma of chloroplasts, using the ATP and NADPH produced in the light-dependent reactions to synthesize glucose.

o as light-independent

Light-independent Reactions : Also known as the Calvin Cycle, the light-independent reactions occur in the stroma of chloroplasts, using the ATP and NADPH produced in the light-dependent reactions to synthesize glucose.

reactions.
In the Calvin cycle, carbon dioxide molecules combine
with six 5-carbon compounds to make twelve 3-carbon
molecules. The chemical energy stored in ATP and NADPH
is passed to the 3-carbon molecules. Two 3-carbon molecules
leave the cycle to be used to make glucose and other organic
compounds. The enzyme rubisco

Rubisco : Rubisco is an enzyme involved in the Calvin Cycle that catalyzes the fixation of CO2 to ribulose bisphosphate, playing a crucial role in converting inorganic carbon to organic forms.

changes ten 3-carbon
molecules into six 5-carbon molecules to continue the cycle.
Because rubisco changes carbon dioxide molecules into
organic molecules that can be used by the cell, it is considered
one of the most important enzymes. Sugar formed in the
Calvin cycle

Calvin Cycle : The Calvin Cycle is a series of light-independent reactions in photosynthesis where atmospheric CO2 and energy stored in ATP and NADPH are used to synthesize glucose and other sugars.

can be used as energy and as building blocks
for complex carbohydrates, such as starch.
Alternative Pathways

Photosynthesis equation : The chemical equation for photosynthesis is 6CO2 + 6H2O → C6H12O6 + 6O2, showing how carbon dioxide and water are converted into glucose and oxygen using light energy, primarily within the chloroplasts of plant cells.

Photosynthesis might be diffi

Photosynthesis equation : The chemical equation for photosynthesis is 6CO2 + 6H2O → C6H12O6 + 6O2, showing how carbon dioxide and water are converted into glucose and oxygen using light energy, primarily within the chloroplasts of plant cells.

cult for plants that grow in
hot, dry environments. Many plants in extreme climates have
evolved other photosynthesis pathways.
Tropical plants such as sugar cane

Sugar cane : A tropical plant that utilizes the C4 pathway for photosynthesis to efficiently manage water in hot climates.

and corn

Corn : A C4 plant well known for efficient photosynthesis in sunny, hot environments.

use the C4
path

C4 Pathway : The C4 pathway is a photosynthetic process in some plants that fixes carbon dioxide into 4-carbon compounds, allowing efficient photosynthesis at low CO2 concentrations, minimizing water loss in hot climates.

way. Instead of the 3-carbon molecules of the Calvi

Calvin Cycle : The Calvin Cycle is a series of light-independent reactions in photosynthesis where atmospheric CO2 and energy stored in ATP and NADPH are used to synthesize glucose and other sugars.

n
cycle

Calvin Cycle : The Calvin Cycle is a series of light-independent reactions in photosynthesis where atmospheric CO2 and energy stored in ATP and NADPH are used to synthesize glucose and other sugars.

, C4 plants fi x carbon dioxide into 4-carbon molecules.
Less water is lost in the C

C4 pathway reduces water loss in plants : C4 plants like sugar cane and corn fix carbon dioxide into 4-carbon molecules, which is more water-efficient and optimal for hot climates.

4 pathway. These plants keep their

C4 pathway reduces water loss in plants : C4 plants like sugar cane and corn fix carbon dioxide into 4-carbon molecules, which is more water-efficient and optimal for hot climates.

. These plants keep their
stomata closed during hot days to minimize water loss.
What are CAM plants?
Another alternative pathwa

CAM Pathway : The CAM pathway is a photosynthetic adaptation in some plants to arid conditions, where CO2 is absorbed at night and stored for use during daylight in the Calvin Cycle.

y is called the CAM

CAM Pathway : The CAM pathway is a photosynthetic adaptation in some plants to arid conditions, where CO2 is absorbed at night and stored for use during daylight in the Calvin Cycle.

pathway.
CAM plants live in deserts, salt marshes, and other environments
where access to water is limited. Cac

Cacti : CAM plants adapted to deserts that minimize water loss by opening their stomata at night.

ti and orchi

Orchids : A diverse group of flowering plants, some of which use CAM photosynthesis to adapt to varied environments.

ds are CAM
plants. Carbon dioxide enters the leaves of CAM plants only
at night, when the atmosphere is cooler and more humid.
The plants also fi x carbon dioxide into organic compounds at
night. During the day, carbon dioxide is released from organic
compounds in the plants. The carbon dioxide enters the Calvin

Calvin Cycle : The Calvin Cycle is a series of light-independent reactions in photosynthesis where atmospheric CO2 and energy stored in ATP and NADPH are used to synthesize glucose and other sugars.

cycle

Calvin Cycle : The Calvin Cycle is a series of light-independent reactions in photosynthesis where atmospheric CO2 and energy stored in ATP and NADPH are used to synthesize glucose and other sugars.

at that point. The CAM pat

CAM Pathway : The CAM pathway is a photosynthetic adaptation in some plants to arid conditions, where CO2 is absorbed at night and stored for use during daylight in the Calvin Cycle.

CAM pathway minimizes water loss while allowing adequate carbon uptake : CAM plants, such as cacti and orchids, open their stomata at night to take in carbon dioxide and fix it in organic compounds, reducing water loss in arid environments.

hway minimizes water loss,

CAM Pathway : The CAM pathway is a photosynthetic adaptation in some plants to arid conditions, where CO2 is absorbed at night and stored for use during daylight in the Calvin Cycle.

CAM pathway minimizes water loss while allowing adequate carbon uptake : CAM plants, such as cacti and orchids, open their stomata at night to take in carbon dioxide and fix it in organic compounds, reducing water loss in arid environments.

while allowing for adequate carbon uptake.

CAM Pathway : The CAM pathway is a photosynthetic adaptation in some plants to arid conditions, where CO2 is absorbed at night and stored for use during daylight in the Calvin Cycle.

CAM pathway minimizes water loss while allowing adequate carbon uptake : CAM plants, such as cacti and orchids, open their stomata at night to take in carbon dioxide and fix it in organic compounds, reducing water loss in arid environments.

7. Name the main energy-
storing products of each

Light Reactions of Photosynthesis : Light reactions of photosynthesis occur in the thylakoid membranes, where light energy is converted into chemical energy in the form of ATP and NADPH, and oxygen is released as a byproduct.

Photosynthesis equation : The chemical equation for photosynthesis is 6CO2 + 6H2O → C6H12O6 + 6O2, showing how carbon dioxide and water are converted into glucose and oxygen using light energy, primarily within the chloroplasts of plant cells.

Phases of photosynthesis : Photosynthesis occurs in two phases: light-dependent reactions, converting light energy into chemical energy as ATP and NADPH, and light-independent reactions, using these to form glucose.

Photosynthesis involves photosystems and electron transport : Photosystem I and II are made of light-absorbing pigments and proteins crucial for light reactions, facilitating electron movement and energy transfer in photosynthesis.

phase of photosynthesis

Light Reactions of Photosynthesis : Light reactions of photosynthesis occur in the thylakoid membranes, where light energy is converted into chemical energy in the form of ATP and NADPH, and oxygen is released as a byproduct.

Photosynthesis equation : The chemical equation for photosynthesis is 6CO2 + 6H2O → C6H12O6 + 6O2, showing how carbon dioxide and water are converted into glucose and oxygen using light energy, primarily within the chloroplasts of plant cells.

Phases of photosynthesis : Photosynthesis occurs in two phases: light-dependent reactions, converting light energy into chemical energy as ATP and NADPH, and light-independent reactions, using these to form glucose.

Photosynthesis involves photosystems and electron transport : Photosystem I and II are made of light-absorbing pigments and proteins crucial for light reactions, facilitating electron movement and energy transfer in photosynthesis.

.
8. Name two places where
CAM plants live.
Reading Essentials Chapter 8 Cellular Energy
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