Date: December 10, 2015
Aim #34: How do plants carry out the process of
photosynthesis?
Do Now: Warm-Up Notebook
Date
Title of Activity
12/10
Light! Pigments! Action!
Page #
60
HW:
1) Article- Changing Colors of Leaves
2) Bring in headphones/ear buds for computer lab please 
3) Missing work?? Please get in ASAP
4) Plant Packet (follow calendar of suggested deadlines!!)
Aim #34: How do plants carry out
the process of photosynthesis?
1) What is the formula of Aerobic Cell
Respiration?
C6H12O6 + 6O2  6CO2 + 6H2O + 38ATP
2) What is the formula of Photosynthesis?
Light + 6H2O + 6CO2 ----------> C6H12O6+ 6O2
3) What is the difference between the two?
Cell Respiration- there is a “fall” of electrons from
glucose to O2 (ETC) that releases energy to form
ATP.
Photosynthesis- energy from sunlight is used to boost
electrons from water “uphill” to produce glucose.
4) Where in the cell does photosynthesis take
place?
Inner
Stroma Membrane
Grana
Thylakoid
Outer Membrane
Chloroplast
5) Two Main Stages of Photosynthesis:
a) Light Reactions- convert the energy in
sunlight to chemical energy. It takes place in
the membrane of the thylakoids.
b) Calvin Cycle- makes glucose from the
atoms of CO2, plus the H atoms and high
energy electrons of NADPH & ATP produced
during the light reactions. Takes place in the
stroma.
Photosynthesis
https://www.youtube.com/watch?v=W-PgR8dYpOo
(3 minutes)
6) Details of the Light Reactions:
Light + 6H2O + 6CO2 ----------> C6H12O6+ 6O2
O2 released into atmosphere
+ H2 O
H atoms & electrons
Light splits water into oxygen, H atoms, and electrons
This is called photolysis
Light Reactions:
H atoms & electrons + NADP+
ETC
ATP
NADPH
7) What is Chlorophyll?
Are the pigments (chemical
compounds that give a
substance its color) found in
the chloroplasts.
There are different types of
pigments in the
chloroplasts.
Ex: Chlorophyll a, Chlorophyll b, Carotenoids
8) What is the role of the chlorophyll pigments
in the light reactions?
Within the thylakoid membrane, chlorophyll and other
molecules are arranged in clusters called photosystems
The clusters of pigment molecules act like a light
gathering panel (solar collector)
What is the role of Chlorophyll?
Energy
Ground State
Excited State
Ground
State
Each time a pigment molecule absorbs light energy,
its electrons gain energy and become “excited”.
Almost immediately, the excited electron falls back to
the ground state & transfers the energy to its
neighboring molecule
What is the role of Chlorophyll?
This transfer of energy to neighboring pigment
molecules sets off a chain reaction.
The chain reaction will continue until it reaches the
reaction center of the photosystem.
Here the electron is captured by the primary electron
acceptor.
What does the primary electron acceptor do
with the electrons?
The electrons are sent down an electron transport
chain which helps produce some ATP.
Next, the electrons are passed on to a second
photosystem.
This photosystem passes the light-excited electrons
to NADP+ and combine with the H+ from H2O
forming NADPH.
Let’s take a look at this:
Primary Electron Acceptor
ETC
Electron
Acceptor
(protein)
ePhotosystem
H
O+2
Electron Transport Chain
Electron
eAcceptor
(protein)
Electron
Acceptor
Electron
Acceptor
9) Details of the Calvin Cycle (Dark Reaction or
Carbon Fixation):
2)Calvin Cycle- makes glucose from the
atoms of CO2, plus the H atoms and high
energy electrons of NADPH & ATP produced
during the light reactions. Takes place in the
stroma.
CO2 + NADPH + ATP  G3P Glucose
Comes from
atmosphere
Comes from
Light Reactions
Light Reactions & Calvin Cycle:
Calvin Cycle
Photosynthesis Summary
Sunlight  Chemical bonds in
glucose
Materials used carbon dioxide, and water
Energy
Materials
produced
Time frame
Glucose, water, and oxygen
Location
chloroplasts
Importance
Stores energy from sun… made
available to other organisms
Daylight hours
Light Energy
Water
Carbon Dioxide
Oxygen
Glucose
A more detailed summary:
AKA
Light dependent
reaction
Light independent
reaction
Light reaction
Dark reaction, Calvin
Cycle or carbon fixation
Location Grana
Stroma
What’s
going
on…
•Enzyme Rubisco
converts inorganic CO2
into organic glucose by
combining two PGAL
molecules (a 3 C
molecule)
•Water is split
(photolysis)
•Oxygen is released
into atmosphere
•NADPH and ATP are
made to be used in
Light Independent
reaction
Amoeba Sisters
https://www.youtube.com/watch?v=uixA8ZXx0KU
(~8 minutes)
Light-dependent reaction
1. In thylakoid spaces of the grana in the
chloroplast.
2. Sunlight strikes the chlorophyll contained within
the thylakoid spaces which causes electrons to
become excited and infused with energy.
3. Electrons are transferred down an electron
transport chain.
4. The energy in the electrons is used to set up a
proton gradient across the membrane of the
thylakoid spaces.
5. Protons flowing back across the thylakoid
membrane according to the concentration
gradient are harnessed to produce ATP and
NADPH (the reduced form of NADP).
6. As a by-product of this process, molecules of water are split into
molecular hydrogen and oxygen (photolysis).
7. The plant needs the hydrogen to produce ATP.
8. The oxygen you’re breathing right now is some of that waste
product.
9. The purpose of the light reaction is to make the
usable energy necessary to run the lightindependent reaction.
Light-independent reaction
1. AKA the Calvin cycle, or carbon fixation or
dark reaction
2. The reaction takes place in the stroma of the
chloroplast
3. In the dark reaction, the carbon from carbon
dioxide is added to the five-carbon sugar
ribulose bisphosphate (RuBP) to produce a sixcarbon compound.
4. This unstable six-carbon sugar is immediately
split into two three-carbon molecules, which in a
chain reaction using the ATP and NADPH from
the light reaction are modified to form
glyceraldehyde 3-phosphate.
5. The glyceraldehyde 3-phosphate can be synthesized
into carbohydrates such as glucose.
6. One of the glyceraldehyde 3-phosphate molecules is
made into carbohydrates, while the other molecules
remain in the Calvin cycle to serve as raw materials for
the next round of production.