AP Biology
John D. O’Bryant School of
Mathematics and Science
November 7, 2012
AP Biology
Agenda
 Do Now (Table of Contents)
 HW discussion; Lab discussion
 Photosynthesis: Modeling
AP Biology
Table of Contents
(Notes/Classwork)
Date
Topic
11/1/12
Cellular Respiration summary; Photosynthesis:
Overview
11/2/12
Photosynthesis: Overview, Light Reactions;
Pigment lab
11/5/12
Photosynthesis: Calvin Cycle, Light Reactions
11/6/12
Photosynthesis: Modeling
11/7/12
Photosynthesis: Calvin Cycle, Modeling
Page
number
HW
1. What is photorespiration? How is the problem of photorespiration solved in some
species of plants?
2. Discuss the consequences of global climate change to photorespiration.
3. Explain why it takes six turns of the Calvin Cycle to produce a molecule of
glucose.
4. Do a little accounting.
a. How many CO2, H2O, NADPH, and ATP molecules are needed to produce a
molecule of glucose?
b. How many O2 molecules are produced in the production of one molecule of
glucose?
c. How many turns of the Calvin Cycle are needed to produce one molecule of
glucose?
5. Describe the major differences between C3, C4, and CAM plants.6.
Use two examples from photosynthesis to explain the relationship between
structure and function in living organisms.
AP Biology
Modeling Photosynthesis
Task:
In pairs, build a dynamic model of C3 photosynthesis using cutout pieces
of paper to represent the molecules, ions, and membrane transporters or
pumps. You should be able to manipulate or move carbon dioxide and
water and its breakdown products through the various steps of the
process.
AP Biology
Quiz
 1. Cyclic electron flow may be photoprotective (protective to lightinduced damage). Which of the following experiments could provide
information on this phenomenon?
A) using mutated organisms that can grow but that cannot carry
out cyclic flow of electrons and compare their abilities to
photosynthesize in different light intensities
B) using plants that can carry out both linear and cyclic electron flow, or
only one or another of thee processes, and measuring their light
absorbance
C) using bacteria that have only cyclic flow and look for their
frequency of mutation damage
D) using bacteria with only cyclic flow and measuring the number and
types of photosynthetic pigments they have in their membranes
E) using plants with only photosystem I operative and measure
how much damage occurs at different wavelengths.

AP Biology
Quiz
 2. What is the primary function of the Calvin cycle?

A) use ATP to release carbon dioxide
B) use NADPH to release carbon dioxide
C) split water and release oxygen
D) transport RuBP out of the chloroplast
E) synthesize simple sugars from carbon dioxide
AP Biology
Quiz
 3. Which of the following requires ATP?

A) light reactions alone
B) the Calvin cycle alone
C) both the light reactions and the Calvin cycle
D) neither the light reactions nor the Calvin cycle
E) photophosphorylation
AP Biology
Quiz
 4. Which of the following produces NADH?

A) light reactions alone
B) the Calvin cycle alone
C) both the light reactions and the Calvin cycle
D) neither the light reactions nor the Calvin cycle
E) photophosphorylation
AP Biology
Quiz
 5. Which of the following produces NADPH?

A) light reactions alone
B) the Calvin cycle alone
C) both the light reactions and the Calvin cycle
D) neither the light reactions nor the Calvin cycle
E) photophosphorylation
AP Biology
Quiz
 6. Which of the following requires CO2?

A) light reactions alone
B) the Calvin cycle alone
C) both the light reactions and the Calvin cycle
D) neither the light reactions nor the Calvin cycle
E) photophosphorylation
AP Biology
Quiz
 7. The pH of the inner thylakoid space has been measured, as
have the pH of the stroma and of the cytosol of a particular plant
cell. Which, if any, relationship would you expect to find?

A) The pH within the thylakoid is less than that of the stroma.
B) The pH of the stroma is higher than that of the other two
measurements.
C) The pH of the stroma is higher than that of the thylakoid
space but lower than that of the cytosol.
D) The pH of the thylakoid space is higher than that anywhere
else in the cell.
E) There is no consistent relationship.
AP Biology
AP Biology
2007-2008
Photosynthesis:
Life from Light and Air
AP Biology
2007-2008
Ghosts of Lectures Past
(storage)
AP Biology
2007-2008
Stomates
AP Biology
Photosynthesis:
The Calvin Cycle
Life from Air
AP Biology
2007-2008
Whoops!
Wrong
Calvin…
The
Calvin
Cycle
AP Biology
1950s | 1961
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
 that can be moved around plant
 saved for a rainy day

carbon + water + energy  glucose + oxygen
dioxide
light  C H O + 6O
AP Biology6CO2 + 6H2O +
6 12 6
2
energy
Light reactions
 Convert solar energy to chemical
energy
ATP

ATP  energy

NADPH  reducing power
 What can we do now?
  build stuff !!
AP Biology
photosynthesis
How is that helpful?
 Want to make C6H12O6
synthesis
 How? From what?
What raw materials are available?

CO2
NADPH
carbon fixation
reduces CO2
NADP
C6H12O6
AP Biology
NADP
From CO2  C6H12O6
 CO2 has very little chemical energy

fully oxidized
 C6H12O6 contains a lot of chemical energy

highly reduced
 Synthesis = endergonic process

put in a lot of energy
 Reduction of CO2  C6H12O6 proceeds in
many small uphill steps
each catalyzed by a specific enzyme
 using energy stored in ATP & NADPH

AP Biology
From Light reactions to Calvin cycle
 Calvin cycle

chloroplast stroma
 Need products of light reactions to
drive synthesis reactions
stroma
ATP
 NADPH

ATP
thylakoid
AP Biology
C
C
Calvin cycle
C C C C C
1C
C C C C C
3. Regeneration
C C C C C
of RuBP
RuBP
starch,
sucrose,
cellulose
& more
ribulose bisphosphate
3 ATP
H H H
|
| |
C–C–C
AP Biology
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
CO2
1. Carbon fixation
C C C C C C
RuBisCo
ribulose
bisphosphate
carboxylase
3 ADP
used
to make
glucose
C=C=C
5C
C
C C C C C C
6C
C C C C C C
5C
glyceraldehyde-3-P
G3P
C C C
PGA
phosphoglycerate
3C
6 NADP
C
C
C
C
C
C
6 ATP
2. Reduction
6 NADPH
3C
C
C
C
C
C
C
3C
6 ADP
C
C
C
C
C
C
H
|
H
|
H
|
Remember
G3P?
glycolysis
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
To G3P and Beyond!
 Glyceraldehyde-3-P
To G3P
and beyond!
end product of Calvin cycle
 energy rich 3 carbon sugar
 “C3 photosynthesis”

 G3P is an important intermediate
 G3P   glucose   carbohydrates
  lipids   phospholipids, fats, waxes
  amino acids   proteins
  nucleic acids   DNA, RNA
AP Biology
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)

6 turns of Calvin cycle = 1 C6H12O6 (6C)

6 CO2  1 C6H12O6 (6C)

18 ATP + 12 NADPH  1 C6H12O6

AP Biology
any ATP left over from light reactions
will be used elsewhere by the cell
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
light  ATP + NADPH + O
2
energy
H 2O +
H2O
sunlight
Energy Building
Reactions
NADPH
ATP
AP Biology
O2
 produces ATP
 produces NADPH
 releases O2 as a
waste product
Calvin Cycle
CO2 + ATP + NADPH  C6H12O6 + ADP + NADP
CO2
ADP
NADP
Sugar
Building
Reactions
NADPH
ATP
AP Biology
sugars
 builds sugars
 uses ATP &
NADPH
 recycles ADP
& NADP
 back to make
more ATP &
NADPH
Putting it all together
light
CO2 + H2O + energy  C6H12O6 + O2
H2O
CO2
sunlight
ADP
Energy NADP
Building
Reactions
Sugar
Building
Reactions
NADPH
ATP
AP Biology
O2
sugars
Plants make both:
 energy
 ATP & NADPH
 sugars
even though
this equation
is a bit of a lie…
it makes a
better story
Energy cycle
sun
Photosynthesis
light
CO2 + H2O + energy  C6H12O6 + O2
plants
CO2
glucose
H2O
animals, plants
ATP
C6H12O6 + O2  energy + CO2 + H2O
Cellular Respiration
AP Biology
The Great Circle
of Life,Mufasa!
ATP
O2
Summary of photosynthesis
6CO2 + 6H2O + light  C6H12O6 + 6O2
energy










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?
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

AP Biology
heterotrophs are dependent on plants as
food source for fuel & raw materials
The poetic perspective…
 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
Plant pigment lab
AP Biology