Photosynthesis:
The Calvin Cycle
Life from Air
Take CO2 out of atmosphere and fix it into organic
molecules present in stroma of chloroplast and
generate organic molecules for plants use
Melvin Calvin: Berkeley professor who discovered steps
of Calvin cycle in 50s, won noble prize in 1961
AP Biology
2007-2008
Remember what it means to be a plant…
Need to produce all organic molecules
necessary for growth
carbohydrates, lipids, proteins, nucleic acids
Need to store chemical energy (ATP)
produced from light reactions
in a more stable form
can be moved around plant
saved for a rainy day
carbon + water + energy
dioxide
light
AP Biology6CO2 + 6H2O +
energy
glucose + oxygen
C6H12O6 + 6O2
Light reactions
Convert solar energy to chemical
energy
energy
ATP
NADPH
ATP
reducing power
Reduce CO2, generate organic molecules for
plant use
What can we do now?
build stuff !!
lightreact.io
AP Biology
TinFyTacT
photosynthesisy
How is that helpful?
Want to make C6H12O6
synthesis
How? From what?
What raw materials are available?
I
CO2
carbon fixation
Carbon Fixation
As well as ATP from light reactions
In Calvin cycle, once NADPH is oxidized and drops
electrons it’s converted back to NADP that goes
back to light reactions to collect more electrons
(recycling NADP and ADP to go to light reactions)
When NADPH is oxidized it reduced carbon dioxide
NADPH
NADP
C6H12O6
AP Biology
reduces CO2
NADP
Carbon as CO2 gas out of atmosphere into organic molecules in living things (carbon fixation)
From CO2
C6H12O6
CO2 has very little chemical energy
LL
C H O contains a lot of chemical energy
Tyr.edinTTitttTTondson
ox.Tgen
fully oxidized
en.TT
g
6
12
6
highly reduced
TSUNG
txstored.in
TfTar TIS
Synthesis = endergonic process
e
put in a lot of energy goingFT
g
Reduction of CO2 C6H12O6 proceeds in
many small uphill steps
tFfgF_Tdgg
each catalyzed by a specific enzymeuseators.ters
using energy stored in ATP & NADPH
AP Biology
From Light reactions to Calvin cycle
Calvin cycle can’t take place without products of light reactions...drive reactions
Calvin cycle
Chloroplast stroma
____________________
L
g
tx.int
Need products of light reactions to
drive synthesis reactions
ATP
________________
________________
NADPH
eFTdtodriveCalvincycle
ATP
Calvin cycle not dark reaction b/c
plant can’t generate ATP or NADPH
within chloroplasts in dark
thylakoid
AP Biology
stroma
C
Calvin cycle
3Stagesphases
1C
C C C C C
3.
Regeneration
3. Regeneration
of RuBP
of RuBP
starch,
sucrose,
cellulose
& more
H H H
|
| |
C–C–C
AP Biology
C C C C C
RuBP
ribulose bisphosphate
5C
3 ATP
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
CO2
5C
RuBisCo
RuBisCo
glyceraldehyde-3-P
G3P
3C
C C C
6 NADP
6C
PGA
phosphoglycerate
C C C C C C
C C C C C C
3C
C
C
C
C
C
C
C
C
C
C
C
C
6 ATP
2.
Reduction
2. Reduction
6 NADPH
1.
1. Carbon
Carbon Fixation
fixation
C C C C C C
ribulose
bisphosphate
carboxylase
3 ADP
used
to make
glucose
C=C=C
C C C C C
C
3C
6 ADP
C
C
C
C
C
C
H
|
H
|
H
|
Each CO2 added to 1 5 C
in chloroplast stroma
s
caninaiscoverea
Enzyme fixes/attaches CO2 to RuBP, most abundant enzyme/protein
(thousands of copies in each chloroplast in every mesophyll cell
(30-40 chloroplasts)in a plant
1 CO2 + 5 C = 6 C
2 phosphate groups destabilize add C to 5 C chain
po gyc te
e
E
gasp
Back
ATP & NADPH made in light
reactions used, 6 3-PGA
phosphorylated by 6 ATP
(1 ATP per 1 3-PGA
phosphorylated, make 3 C
w/ 2 phosphate groups, 18
C),reduced by NADPH &
added electrons then
oxidized NADPH recycles
NADP+ & ADP back to light
reactions, make 6 G3P
(intermediate molecule in
cellular respiration
glycolysis), 15 C to 18 C
(3 CO2 = 1 net G3P leaves
+ 5 G3P stay (15 C back))
a
compounatorade
starting
rema.in
gtxg
e
ftE
or
reactions
Calvin cycle uses more ATP (+3) than NADPH
Remember
G3P?
glycolysis
Plants generate G3P, run glycolysis backwards
to converts G3P into glucose
glucose
C-C-C-C-C-C
2 ATP
2 ADP
fructose-1,6bP
P-C-C-C-C-C-C-P
DHAP
P-C-C-C
G3P
glyceraldehyde
3-phosphate
C-C-C-P
2 NAD+
2
4 ADP
AP Biology
Photosynthesis
pyruvate
C-C-C
4 ATP
cam
4or
cosphotosynthesiscart.c
To G3P and Beyond!
To G3P
and beyond!
Glyceraldehyde-3-P
Tt
sY
end product of Calvin cycle
g 3 carbon sugar
energy rich
C3 photosynthesis
“___________________”
G3P is an important intermediate
G3P
glucose
carbohydrates
iii
AP Biology
it's
lipids
phospholipids, fats, waxes
amino acids
proteins
nucleic acids
DNA, RNA
RuBisCo
Enzyme which fixes carbon from air
__________________________________
ribulose bisphosphate carboxylase
the most important enzyme in the world!
it makes life out of air!
definitely the most abundant
enzyme
__
I’m green
with envy!
AP Biology
It’s not easy
being green!
Accounting
The accounting is complicated
3 turns of Calvin cycle = 1 G3P
3 CO2
1 G3P (3C)
Hunt
It
6 turns of Calvin cycle = 1 C6H12O6 (6C)
6 CO2
1 C6H12O6 (6C)
18 ATP + 12 NADPH
ftp.E.EE
1 C6H12O6
any ATP left over from light reactions
will be used elsewhere by the cell
AP Biology
e
EE
Photosynthesis summary
Light reactions
__________________
Produced ATP
Produced NADPH
__________________
Consumed H2O
__________________
Produced O2 as byproduct
__________________
Calvin cycle
Consumed CO2
__________________
Produced G3P (sugar)
__________________
Regenerated ADP
__________________
Regenerated NADP
__________________
AP Biology
ADP
NADP
Light Reactions
H 2O +
thylakoid
light
energy
H2O
sunlight
Energy Building
Reactions generate
NADPH
ATP
H2o
splits
waste
AP Biology
O2
used
forcellularrespirationorleave
stomata
photosynthesis
through
after
ATP + NADPH + O2
Produces ATP
_______________
Produces NADPH
_______________
_______________
Releases O2 as a waste
product
_______________
Calvin Cycle
stroma
CO2 + ATP + NADPH
C6H12O6 + ADP + NADP
used
Builds sugars
____________
____________
Uses ATP and NADPH
____________
Recycles
ADP and NADP
____________
____________
CO2
Recycled
ADP
NADP
Sugar
Building
Reactions
back to make
more ATP &
NADPH
NADPH
ATP
pluscoutatmospnereinto
compounds
instroma
organic
generate
Esp
AP Biology
sugars
aaroontixation
Putting it all together
light
CO2 + H2O + energy
H2O
CO2
sunlight
ADP
Energy NADP
Building
Reactions
Sugar
Building
Reactions
NADPH
ATP
AP Biology
O2
sugars
C6H12O6 + O2
Plants make both:
Energy
____________
____________
ATP and NADPH
Sugars
____________
even though
this equation
is a bit of a lie…
it makes a
better story
create
cycleinplanet
energy
Energy cycle
sun
Photosynthesis day
Photosynthesis
productor
light
CO2 + H2O + energy
atmosphere
soil
reactantscr
C6H12O6 + O2
Plants
________________
CO2
CO
2
HH2O
2O
Glucose
navemitanonaria
Animals, plants
________________
producers
C6H12O6 + O2
reactant
p
ATP
+
CO
+
energy e 2 H2O
CellularRespiration
respiration day
Cellular
might
AP Biology
The Great Circle
of Life,Mufasa!
ATP
O2
O
2
Summary of photosynthesis
6CO2 + 6H2O + light
energy
C6H12O6 + 6O2
Where did the CO2 come from?
Where did the CO2 go?
Where did the H2O come from?
Where did the H2O go?
Where did the energy come from?
What’s the energy used for?
What will the C6H12O6 be used for?
Where did the O2 come from?
Where will the O2 go?
What else is involved…not listed in this equation?
Atmosphere
Stroma, attach to RuBP to generate G3P to make glucose
Soil, absorbed by roots up to leaves by xylem used in light reactions
as source of electrons
Electrons used in ETC of light reactions to make proton gradient used to make ATP then in NADPH molecules to
drop electrons at Calvin cycle in organic compounds to G3P and glucose, O2 released as waste product, protons
from water remain in thylakoid build up gradient
Sun, photosynthesis is solar powered
Help reduce carbon dioxide and form G3P
Energy molecule, broken down in cellular respiration to generate ATP
Splitting of water
Leave chloroplast, leave cell, exit leaf through stomata
ATP & NADPH
AP Biology
Supporting a biosphere
On global scale,
photosynthesis is the
most important process
for the continuation of life on Earth
each year photosynthesis…
captures 121 billion tons of CO2
synthesizes 160 billion tons of carbohydrate
heterotrophs are dependent on plants as
food source for fuel & raw materials
AP Biology
The poetic perspective…
artist
All the solid material of every plant
was built by sunlight out of thin air
All the solid material of every animal
was built from plant material
air
AP Biology
sun
Then all the plants, cats,
dogs, elephants & people …
are really particles of air woven
together by strands of sunlight!
If plants can do it…
You can learn it!
Ask Questions!!
AP Biology
2007-2008