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antennae complex - The region of the chloroplast thylakoid containing a few hundred
chlorophyll a, chlorophyll b and carotenoid molecules linked together by proteins embedded in the membrane. The antennae complex is the main unit involved in harvesting light
energy during photosynthesis. It acts as a funnel to transfer excited electrons to the reaction center, which passes them along to the eltectron transport chain.
Graphic representation of antennae complex
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ATP (adenosine triphosphate) – A relatively stable, high energy molecule used to fuel
chemical reactions within cells. ATP is the ‘universal energy carrier’ molecule in nature,
performing energy exchange and energy transport functions in all living things. ATP is an
adenine-containing nucleoside triphosphate that releases free energy when one of its
phosphate bonds is hydrolyzed – a reaction that yields ADP, Adenosine diphosphate, as a
product. The ADP is recycled to ATP through the addition of an activated phosphate
group coupled to energy-producing reactions.
NH2
N
N
O–
–
O
P
O–
O
P
O–
O
P
O
N
CH2
N
O
O
O
O
OH
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ATP-synthase - A protein complex embedded in the membrane of the thylakoids that
produces ATP by harvesting the proton motive force – potential energy from a hydrogen
ion gradient accross the thylakoid membrane. As these H+ ions channel back through
ATP synthase, the enzyme system harvests the potential energy, converting it into chemical bond energy as a phosphate is added to ADP. ATP synthase performs a similar function in cellular respiration at the innner membrane of the mitochondrion.
Graphic depiction of ATP synthase.
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bundle sheath cells - Cells that surround (and sheath) the vascular bundles in plant
leaves. In most plants, these cells primarily provide protection for the plant’s water carrying system. However, many plants that live in hot, dry climates, have enlarged and
tightly-packed bundle sheath cells. Chloroplasts in these cells are the main location for
the Calvin cycle. Such plants use their mesophyll cells primarily to capture and transfer
CO 2 to the bundle sheath cells. The CO 2 is incorporated into a four carbon compound,
giving these plants the designation, C 4 plants.
upper epidermis
palisade mesophyll cells
vascular tissue - vein
bundle sheath cells
spongy mesophyll
Stoma
lower epidermis
air
Graphic cutaway of leaf.
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C 3 plants - The ‘normal’ biochemical pathway for incorporating carbon dioxide CO 2 in
plant cells involves the reaction of CO 2 with the five-carbon sugar, ribulose biphosphate.
This reaction is catalyzed by the enzyme, rubisco, and the six-carbon intermediate
formed rapidly splits into two molecules of the three-carbon compound, 3-phosphoglycerate. This three-carbon molecule enters the Calvin cycle - a series of linked reactions
which ultimately forms new molecules of sugar for use in the plant. Most plants utilize
this pathway, and are called C 3 plants in reference to the three-carbon intermediate first
formed during carbon fixation.
CO*
CH2
C
O
Modes of Carbon Fixation Poster
P
O
O-
(catalyzed by)
O
C
O
rubisco
CHOH
CHOH
CHOH
CH2
C
O-
CH2 O
O
P
Ribulose $%&'bisphosphate
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CHOH
P
CH2 O
P
'Phosphoglycerate
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C 4 plant - Many plants that live in hot, dry
climates are adapted to overcome a shortfall of the ribulose bisphosphate/rubisco
system used to fix CO 2 in photosynthesis.
The problem lies in the need for these
plants to shut their stomata to avoid water
loss, which in turn, causes oxygen to build
up and bind with rubisco, drastically cutting
down the efficiency of carbon fixation. C 4
plants have enlarged and tightly-packed
bundle sheath cells where chloroplasts act
as the main location for the Calvin cycle.
Such plants use their mesophyll cells primarily to capture and transfer CO 2 to the
bundle sheath cells, which arrives in the
form of a four carbon compound, giving
these plants the designation, C 4 plants. C 4
plants include corn, cactuses, many
suculents, and a variety of other plants.
CO2
PEP carboxylase
Air
Space
ADP
Malate
ATP
Pyruvate
CO2
Bundle
Sheath Cell
Calvin
Cycle
Sugar
Vascular
Tissue
(Vein)
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Mesophyll
Cell
Oxalocetate
PEP
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Calvin cycle - The major metabolic
pathway used in plants used to turn
CO 2 into sugar during photosynthesis.
Carbon dioxide entering the cycle is
first ‘fixed’ by reaction with a 5-carbon
sugar (ribulose 1,5-bisphosphate),
forming two 3-carbon intermediates.
These are converted into simple
3-carbon sugars by chemical reduction.
For every 3 CO 2 molecules entering the
cycle, one PGAL (G3P) is removed from
the cycle and used in the cell. The remaining 5 molecules of PGAL continue
the cycle by re-forming 3 molecules of
ribulose 5-bisphosphate, a 5-carbon
intermediate.
3 CO*
( molecules of)
Ribulose $%&'bisphosphate
3
ADP
(+ molecules of)
'Phosphoglycerate
6
3
ATP
ATP
6 ADP
( molecules of)
(+ molecules of)
$%'bisphosphoglycerate
Ribulose &-phosphate
The Calvin Cycle
2 P
6 NADH0H0
6 NAD0
6 P
(& molecules of)
Glyceraldehyde 'phosphate
(+ molecules of)
Glyceraldehyde 'phosphate
(Recycled PGAL)
Calvin Cycle Poster
($ molecule of)
Glyceraldehyde 'phosphate
(Harvested PGAL)
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PGAL
(G3P)
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CAM plants - (Crassulacean Acid Metabolism Plants) - Plants that fix carbon dioxide
during the night and store it as 4-carbon organic acids to be used as a source of CO 2
during the day. This group of plants includes cacti, pineapples and members of the
stonecrop family, Crassulaceae (thus the name). These plants tend to live in hot dry
environments, and are adapted to close their stomata during the day and open them at
night, when the plant is less likely to suffer water loss. During the day, when the stomata
are closed, the 4-carbon acids release CO 2 in the plant for use in the Calvin cycle.
Modes of Carbon Fixation Poster
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carbohydrates - Sugars and their sugar polymers. The general formula for a carbohydrate is (CH 2O) n.
H
CH 2O
H
CH 2O
H
CH 2O
H
CH 2O
H
CH 2O
H
CH 2O
OH
OH
OH
O
OH
OH
OH
O
O
OH
OH
O
O
OH
OH
O
O
O
O
O
O
Starch: a polysaccharide carbohydrate
OH
OH
HO
OH
O
H
C
H
C
HOCH2
CH2OH
O
OH
HO
glyceraldehyde
H
H
OH
OH
glucose
(cyclic conformation)
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H
H
OH
CH2OH
OH
O
OH
OH
ribose
(cyclic conformation)
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carbon-fixation reactions - The Calvin cycle fixes the carbon of CO 2 in a reaction that
combines it with a 5-carbon sugar, ribulose bisphosphate or RuBP. The resulting six
carbon intermediate is unstable and immediately splits into two molecules of 3-phosphoglycerate.
Modes of Carbon Fixation Poster
CO*
CH2
C
O
P
O-
O
C
CHOH
O
C
CHOH
CHOH
CH2
O-
CH2 O
O
P
Ribulose $%&'bisphosphate
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O
CHOH
P
CH2 O
P
'Phosphoglycerate
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carotenoid - A pigment molecule that, like chlorophyll, captures light energy in the form
of photons. Plants containing carotenoids often appear yellow-orange.
O
O
One type of carotenoid molecule
(of many different types).
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cellular respiration - The catabolic process where cells release stored energy by breaking down complex molecules using oxygen as a reactant. In eukaryotic cells, these
metabolic reactions take place in the mitochondrion.
Overview of Cellular Respiration
electrons carried on NADH
glucose
Glycolysis
pyruvate
electrons carried
on NADH and FADH*
Krebs
cycle
ATP
Electron
Transport
Chain
Mitochondrion
ATP
Cytoplasm
ATP
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chlorophyll - A pigment that captures energy from sunlight for use in photosynthesis.
Chlorophyll has a porphyrin ring structure (five nitrogen-containing rings linked together)
and a long hydrophobic tail. There are different kinds of chlorophyll with slightly different
molecular structures – chlorophyll a, cholorphyll b and chlorophyll c. Each one absorbs a
distinctive range of wavelengths absorbed. Chlorophyll a is found in all photosynthetic
eukaryotes, cyanobacteria and prochlorophytes (another group of photosynthetic bacteria). Chlorophyll b is found in plants and green algae but not in diatoms, brown algae or
red algae. Among prokaryotes it is present in prochlorophytes but not in cyanobacteria.
Chlorophyll c is found in brown algae, diatoms, and some other single celled algae but
not in plants or prokaryotes.
Photosynthesis Poster
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chloroplast – The organelle in plants, and some green algae, that contains chlorophyll A
and B and is the location of the reactions of photosynthesis. Chloroplasts also store
starch for use by the cell. The chloroplast is one type of plastid. Some algae (such as
diatoms, brown algae, red algae, dinoflagellates, and others) have plastids where photosynthesis occurs, but these are called photosynthetic plastids, not ‘chloroplasts’.
Photosynthesis Poster
Photomicrograph of chloroplasts in
moss cells.
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circadian rhythms - The physiological cycle of approximately 24 hours. These cycles
are present in all eukaryotic organisms. Circadian rhythms persist even in the absence of
external stimuli such as sunlight.
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cyclic electron flow - When photosynthesis is functioning at full capacity, electrons flow from the excited chlorophyll through electron
transport chains associated with
both Photosystems 2 and 1, and
then on to form the reduced energy
carrier, NADPH. Excited electrons
from chlorophyll are replaced by
electrons from water – they do not
cycle back to chlorophyll directly.
This is non-cyclic electron flow.
Non-cyclic electron flow creates
equal quantities of ATP and NADPH
formed by non-cyclic photophosphorylation.
A second pathway, using only Photosystem 1, allows the excited electrons to return
directly to chlorophyll via the electron transfer chain. In this pathway, ATP is formed, but
not NADPH, and H 2O does not supply ‘replacement’ electrons. This alternate pathway is
called cyclic electron flow, and it is used when the cell requires additional ATP to compensate for increasing concentrations of NADPH created as the Calvin cycle uses more
ATP than NADPH. In this pathway, the formation of ATP is called: cyclic photophosphorylation.
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cyclic photophosphorylation - When photosynthesis is functioning at full capacity,
electrons flow from the excited chlorophyll through the electron transport chains
associated with both Photosystems 2 and 1, and then on to form the reduced energy
carrier, NADPH. Excited electrons from chlorophyll are replaced by electrons from water
– they do not cycle back to chlorophyll directly. This is non-cyclic electron flow.
Non-cyclic electron flow creates equal quantities of ATP and NADPH formed by non-cyclic photophosphorylation.
A second pathway, using only Photosystem 1, allows the excited electrons to return
directly to chlorophyll via the electron transfer chain. In this pathway, ATP is formed, but
not NADPH, and H 2O does not supply ‘replacement’ electrons. This alternate pathway is
called cyclic electron flow, and it is used when the cell requires additional ATP to
balance increasing concentrations of NADPH created by the Calvin cycle (which uses
more ATP than NADPH). In this pathway, the formation of ATP is called: cyclic photophosphorylation.
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cytochromes - A group of proteins that have an iron containing heme group integrated
into their conformational structure. Cytochromes are efficient at holding electrons in the
electron transport chain due to the binding capabilities of the heme group. A cytochrome
complex is present in the electron transport chain of photosynthesis and several
cytochromes are present in the electron transport chain of cellular respiration.
Cytochrome complexes on the inner
membrane of the mitochondrion
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electron transport chain - A group of proteins embedded in the membrane of the
thylakoid that harvest energy from excited electrons in Photosystem 1 and Photosystem
2. Each electron transport chain molecule oscillates between the reduced and oxidized
state as it accepts and donates electrons. Some redox reactions in the chain are linked
to the pumping of H+ ions across the thylakoid membrane, thereby forming the hydrogen
ion gradient that drives ATP production.
Graphic of electron transport proteins in thylakoid
membrane.
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endosymbiont – An organism that lives symbiotically within a host is an endosymbiont.
From the Greek roots endon = within, and sumbioun = living together. Many endosymbionts actually live inside the cells of their host. This form of ‘living together’ is very
common among living organisms. For example, lichens are made up of symbiotic fungi
and algae species. Another important example is the endosymbiotic relationship between
large reef-making corals and algal cells living inside their tissues.
Paramecium bursaria – a species of ciliate
protozoan that harbors endosymbiotic algae.
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endosymbiotic theory – A theory describing the evolutionary origin of cell organelles
such as the mitochondrion and chloroplast. The theory suggests that ancient unicellular
organisms consumed other unicellular organisms through phagocytosis and that these
smaller engulfed cells adapted over time to living inside the larger host cell. Eventually,
the endosymbiont cells became integrated into the host cell, with host and symbiont
becomming functionally interdependent. An overwhelming amount of evidence supports
endosymbiotic origins for both the mitochondrion and the plastids (including the
chloroplast).
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ferredoxin - An iron-containing protein in the electron transport chain of Photosystem I in
photosynthesis.
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glucose - A six–carbon aldose monosaccharide with the empirical formula C 6H 12O 6. This
sugar is the major nutrient for cells. Photosynthesis makes glucose from CO 2 and sunlight. Cellular respriation and fermentation break it down for the cell’s use.
O
H
C
CH2OH
H
C
OH
HO
C
H
H
C
OH
H
C
OH
H
C
OH
O
HO
OH
OH
OH
glucose
(cyclic conformation)
H
glucose
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glyceraldehyde phosphate (P-GAL) =
glyceraldehyde 3-phosphate (G3P) - An
extremely important intermediate in many
energy-releasing or energy-storing reactions
of the cell. Names and abbreviations for this
molecule include phosphoglyceraldehyde,
PGAL or glyceraldehyde 3-phosphate, G3P.
In glycolysis it is formed by the splitting of
fructose 1,6-bisphosphate. PGAL is then
passed on to the energy-yielding phase of
glycolysis. In photosynthesis, PGAL, the
main sugar created by the Calvin cycle is a
building block molecule for other sugars
such as glucose, fructose and sucrose.
3 CO*
( molecules of)
Ribulose $%&'bisphosphate
3
3
ADP
6
C
H
OH
H
C
C
6 ADP
( molecules of)
(+ molecules of)
$%'bisphosphoglycerate
Ribulose &'phosphate
The Calvin Cycle
2 P
6 NADH0H0
6 NAD0
6 P
(+ molecules of)
Glyceraldehyde 'phosphate
(Recycled PGAL)
O
P
($ molecule of)
Glyceraldehyde 'phosphate
H
ATP
ATP
(& molecules of)
Glyceraldehyde 'phosphate
O
(+ molecules of)
'Phosphoglycerate
H
Glyceraldehyde 'phosphate
Calvin Cycle Poster
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PGAL
(G3P)
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grana - Stacks of thylakoids inside the chloroplast that are surrounded by the stroma.
Graphic cross-section through a chloroplast showing the stacks of thylakoids that form the grana.
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ground state - The normal energy level for an unexcited molecule.
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guard cell - Cells that border the stomata in the epidermis of a leaf. The guard cells
swell and shrink according to the amount of water available in the plant. When they
shrink and go flaccid, the stomata pores close because there is no pressure on the guard
cell walls to hold them apart. When they swell, the increased turgidity forces the stomata
to open. In addition to the effects of water in the plant, guard cells are also stimulated by
light, CO 2 levels and circadian rhythms.
Photomicrograph of a single stoma showing
the guard cells .
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hydrogen ion gradient - A hydrogen ion gradient is created across the mitochondrial
membrane by electron transport proteins pumping hydrogen ions out ot the innner mitochondrial space. A similar process takes place in the chloroplast, where H+ ions are
pumped into the thylakoid space. The membrane protein, ATP synthase, can convert the
potential energy in this H+ gradient (also known as the proton motive force) into chemical
bond energy by catalyzing the addition of a phosphate group to ADP. This formation of
ATP is thus a chemiosmotic process.
hydrogen ion
(H+)
ATP synthase
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light independent reactions - Also called the dark reactions of photosynthesis, these
reactions take place in the stroma of chloroplasts and are independent of light absorption. The primary light-independent reactions are the reactions of the Calvin cycle, which
convert CO 2 ‘fixed’ in organic molecules, into reduced sugars, utilizing the reducing
power and chemical energy of NADPH and ATP produced by photosystems 1 and 2 and
the electron transport chain.
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light reactions - The light-dependent reactions in photosynthesis, also called the photosynthetic electron transfer reactions, require sunlight (or artificial light) to proceed. These
reactions convert solar energy into chemical energy in the form of ATP and NADPH. During these reactions, electrons from chlorophyll excited by light absorption are replaced by
electrons from a water molecule in a reaction that yields H + ions and oxygen gas, O 2.
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mesophyll cell - The cells present in the mesophyll (or middle) tissue of a leaf. In most
plants, mesophyll cells hold the majority of chloroplasts used in photosynthesis.
upper epidermis
palisade mesophyll cells
bundle sheath cells
Stoma
lower epidermis
air
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NADPH - The reduced form of the energy carrier molecule NADP +, nicotinamide adenine
dinucleotide phosphate. In photosynthesis, NADPH is produced in the photosystem electron transport chain and used up in the Calvin cycle.
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NADP + reductase - The enzyme that catalyzes the transfer of electrons from ferredoxin
to NADP +, creating NADPH.
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non-cyclic electron flow - When
Photosystem I
photosynthesis is functioning at full
Photosystem II
capacity, electrons flow from the exprimary electron
*e'
cited chlorophyll through the electron
acceptor
*e'
*e'
primary electron
'
*e
transport chains associated with both
*e'
acceptor
NADP00
el
'
*e
e
ct
Photosystems II and I, and then on to
ro
n
*e'
tr
*e'
NADPH
an
form the reduced energy carrier,
sp
*e'
or
t
NADPH. Excited electrons from chloch
ai
*e'
n
sunlight energy
*e'
rophyll are replaced by electrons
ADP
from water – they do not cycle back
ATP
P 866
to chlorophyll directly. This is noncyclic electron flow. Non-cyclic
P +56 reaction center
antennae complex
electron flow creates equal quantities
*e'
of ATP and NADPH formed by nonH*O
cyclic photophosphorylation.
*H0 0$/*O*
A second pathway, using only
Non'cyclic electron flow
Photosystem 1, allows the excited
electrons to return directly to chlorophyll via the electron transfer chain. In this pathway, ATP is formed, but not NADPH, and
H 2O does not supply ‘replacement’ electrons. This alternate pathway is called cyclic
electron flow, and it is used when the cell requires additional ATP to compensate for
increasing concentrations of NADPH created by the Calvin cycle (which uses more ATP
than NADPH). In this pathway, the formation of ATP is called: cyclic photophosphorylation.
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H0
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non-cyclic photophosphorylation - When photosynthesis is functioning at full capacity,
electrons flow from the excited chlorophyll through the electron transport chains associated with both Photosystems II and I, and then on to form the reduced energy carrier,
NADPH. Excited electrons from chlorophyll are replaced by electrons from water – they
do not cycle back to chlorophyll directly. This is non-cyclic electron flow. Non-cyclic
electron flow creates equal quantities of ATP and NADPH formed by non-cyclic photophosphorylation.
A second pathway, using only Photosystem 1, allows the excited electrons to return
directly to chlorophyll via the electron transfer chain. In this pathway, ATP is formed, but
not NADPH. Also, H 2O does not supply ‘replacement’ electrons. This alternate pathway is
called cyclic electron flow, and it is used when the cell requires additional ATP to compensate for increasing relative concentrations of NADPH created by the Calvin cycle
(which uses more ATP than NADPH). In this pathway, the formation of ATP is called:
cyclic photophosphorylation.
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PEP carboxylase - The enzyme that
catalyzes the addition of CO 2 to phosphoenolpyruvate (PEP) to form the four-carbon
compound, oxaloacetate. Oxaloacetate can
then store and transfer the CO 2 into other
cells where it can enter the Calvin cycle.
This carbon-fixation pathway is used
primarily by certain plants adapted to dry,
hot conditions; plants appropriately called
C 4 plants in reference to the four-carbon
intermediates, oxaloacetate and malate.
CO2
PEP carboxylase
Air
Space
Mesophyll
Cell
Oxalocetate
PEP
ADP
Malate
ATP
Pyruvate
CO2
Bundle
Sheath Cell
Calvin
Cycle
Sugar
Vascular
Tissue
(Vein)
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phosphoenolpyruvate (PEP) - In glycolysis,
CO2
a three-carbon intermediate that results from
the removal of water from 2-phosphoglycerate by the enzyme enolase. In preparation
for the light-independent reactions of photosynthesis, some plants fix CO 2 by reaction
Air
Space
with PEP to form a four-carbon compound,
oxaloacetate. Plants that use this pathway to
fix carbon are called C4 plants.
PEP carboxylase
Mesophyll
Cell
Oxalocetate
PEP
ADP
Malate
ATP
Pyruvate
CO2
Bundle
Sheath Cell
Calvin
Cycle
OC
O
C
O
Sugar
P
CH2
Phosphoenolpyruvate
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Vascular
Tissue
(Vein)
Carbon fixation in C4 plants.
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photophosphorylation - ATP synthesis driven by light energy. Non-cyclic photophosphorylation involves both Photosystem 1 and Photosystem 2 and yields ATP and NADPH and
results in the production of O 2. Cyclic photophosphorylation cycles energized electrons
back into the electron transport chain from Photosystem 1, producing ATP but producing
no NADPH or O 2.
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photorespiration - Although the enzyme ribulose bisphosphate carboxylase, Rubisco,
adds CO 2 to ribulose 1,5 bisphosphate, it can also bind with oxygen when CO 2 concentration is low and O 2 concentration is high. When this happens, a series of reactions called
photorespiration takes place, releasing CO 2 but producing no ATP or useful energy for
the cell. Photorespiration becomes a serious problem in hot dry climates when plants
shut down their stomata to conserve water - leading to the build up of O 2 and lack of CO 2.
C4 pathways and CAM pathways are adaptations in some plants that respond to the
potential problems created by photorespiration pathways.
Modes of Carbon Fixation Poster
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photosynthesis - The process of harnessing the sun’s light energy with chlorophyll and
other pigment molecules and converting it into chemical energy in the form of sugars.
Photosynthesis involves two sets of biochemical pathways: 1) the light-dependent reactions in which light energy is converted to
chemical energy in the energy carrier molecules, ATP and NADPH and
2) the light-independent reactions, in
which the energy contained in the
energy carriers is used to fix
carbon dioxide and convert it
(through chemical reduction)
into sugar storage
molecules.
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photosystem - A complex of proteins and chlorophyll molecules that catalyzes the conversion of light energy into chemical energy in photosynthesis. There are two
photosystems, Photosystem 2 (also called P680) and Photosystem 1 (also called P700).
Each consists of a reaction center – a complex of proteins and chlorophyll where light
energy is trapped for conversion into chemical energy – and an antenna complex – a
system of light-absorbing pigments that feed excited electrons to the reaction center.
The excited electrons are transferred to proteins in the electron transport chain.
Photosystem I
Photosystem II
primary electron
acceptor
*e'
*e'
el
ec
sunlight energy
*e'
primary electron
acceptor
*e'
tr
*e'
*e'
on
tr
an
*e'
sp
or
*e'
*e'
tc
*e'
ha
in
NADP00 H0
NADPH
*e'
ADP
ATP
P +56
reaction center
P 866
antennae complex
*e'
H*O
*H0 0$/*O*
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pigments - Substances that absorb visible light. Different pigments absorb different
wavelengths of light. The capture of light by a pigment moves an electron in the bonding
system of the absorbing molecule to a higher energy, or ‘excited’, state. In photosynthesis, the excited state electrons are captured, and their energy converted into chemical
bond energy. A number of pigments are involved in light capture in photosynthesis including: chlorophylls, xanthophylls, carotenoids and phycobilins.
Photosynthesis Poster
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primary electron acceptor - The first molecule to accept electrons from the reaction
center during redox reactions after the electrons are excited to a higher energy level by
light energy. The primary electron acceptor traps the excited electron before it can return
to chlorophyll, and subsequently return to the ground state.
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reaction center - A complex of proteins and chlorophyll where light energy is trapped for
conversion into chemical energy. The excited electrons are transferred to proteins in the
electron transport chain.
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redox reaction - Reactions in which electrons are transferred from one atom (in one
compound) to another atom (in a different compound). In all redox reactions both oxidation (loss of electrons) and reduction (gain of electrons) take place.
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ribulose bisphosphate (RuBP) - In photosynthesis, the five carbon sugar that
reacts with carbon dioxide to initiate the
fixation of carbon in the Calvin cycle. The
intermediate formed by the addition of
CO 2 breaks apart into two 3-carbon
3
compounds. Eventually, a 3-carbon
sugar, PGAL, is formed for each 3 molecules of CO 2 entering the cycle, and
ribulose bisphosphate is regenerated.
CH2
O
3 CO*
Calvin Cycle Poster
( molecules of)
Ribulose $%&'bisphosphate
3
ADP
(+ molecules of)
'Phosphoglycerate
6
6 ADP
( molecules of)
(+ molecules of)
$%'bisphosphoglycerate
Ribulose &'bisphosphate
The Calvin Cycle
P
2 P
C
(& molecules of)
Glyceraldehyde 'phosphate
P
Ribulose $%&'bisphosphate
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6 NAD0
(+ molecules of)
Glyceraldehyde 'phosphate
CHOH
O
6 NADH0H0
6 P
O
CHOH
CH2
ATP
ATP
($ molecule of)
Glyceraldehyde 'phosphate
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ribulose bisphosphate carboxylase, rubisco - In photosynthesis, the enzyme of the
Calvin cycle that catalyzes the addition of CO 2 to ribulose bisphosphate to yield an intermediate that quickly splits into two 3-carbon compounds. Found in all photosynthetic
organisms, rubisco is probably the most abundant enzyme on Earth.
Calvin Cycle Poster
CO*
CH2
C
O
P
O
O-
(catalyzed by)
O
C
O
rubisco
CHOH
CHOH
CHOH
CH2
C
O-
CH2 O
O
P
Ribulose $%&'bisphosphate
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CHOH
P
CH2 O
P
'Phosphoglycerate
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starch - a storage polysaccharide in plants. Starch is made up entirely of monomers of
glucose molecules joined by glycosidic linkages. The simplest form, amylose, is
unbranched. Amylopectin is a more complex branched polymer of starch. Plants store
starch as granules in plastids. Starch represents stored energy, because glucose is a
major cellular fuel.
H
CH 2O
H
CH 2O
H
CH 2O
H
CH 2O
H
CH 2O
O
O
OH
O
OH
OH
OH
H
CH 2O
OH
OH
OH
O
O
OH
OH
O
O
O
O
O
O
OH
OH
Starch: a polysaccharide carbohydrate
OH
HO
OH
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stomata (singular - stoma) - Pores in the epidermis of the underside of a leaf that
regulate gas exchange.
Photomicrograph of a group of stomata .
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stroma - The dense inner fluid of the chloroplast that supports the grana.
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sucrose - The disaccharide made of glucose and fructose monomers with a glycosidic
linkage connecting them.
CH2OH
HOCH2
O
O
HO
OH
HO
O
OH
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OH
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thylakoid - One of a series of membrane-surrounded sacs, stacked together in sandwichlike structures called grana within the chloroplast. Thylakoid membranes provide the surface for the light reactions of photosynthesis, while the space surrounding the thylakoids,
the stroma, is the location of the light-independent reactions of photosynthesis.
Cutaway graphics of the chloroplast showing thylakoids.
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thylakoid space - The compartment inside the thylakoid disc, surrounded by the
thylakoid membrane. Like the inter-membrane space of the mitochondrion, this space
provides a closed reservoir where hydrogen ions, H+, are pumped in as electrons travel
through the electron transport chain. The hydrogen ion gradient provides a proton motive
force of potential energy to drive the synthesis of ATP.
Thylakoid membrane
with embedded proteins of the electron
transport chain
Graphic cutaway of the thylakoid.
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visible spectrum - The visible spectrum includes all the wavelengths of light that can be
seen by the human eye. These wavelengths vary from 380 to 750 nm. When combined,
these colors produce white light.
Photosynthesis Poster
$6'& nm
$6' nm
Gamma rays
X'rays
$6 nm
$ nm
UV
$6+ nm::
Infrared
$6? nm
Microwaves
$6 m
Radio waves
Visible Light
56 nm:
;&6 nm
&66 nm
&&6 nm
+66 nm
+&6 nm
866 nm
8&6 nm
The Visible Light Spectrum with Wavelength in Nanometers
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wavelength - The distance between the crests of electromagentic waves. Wavelength
measurements range from less than a nanometer, nm (gamma rays), to more than a
kilometer, km (radio waves).
$6'& nm
$6' nm
Gamma rays
X'rays
$6 nm
$ nm
UV
$6+ nm::
Infrared
$6? nm
Microwaves
$6 m
Radio waves
Visible Light
56 nm:
;&6 nm
&66 nm
&&6 nm
+66 nm
+&6 nm
866 nm
8&6 nm
The Visible Light Spectrum with Wavelength in Nanometers
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