Photosynthesis
Chapter 8
Objectives:
3.0 Identify reactants and products associated with
photosynthesis and cellular respiration and the purposes of
these two processes.
AOD B.3.1 Identify the function of photosynthesis and
cellular respiration.
AOD B.3.2 Describe photosynthesis and cellular respiration,
including their reactants and products.
AOD B.3.3 Recognize the relationship between reactants and
products associated with photosynthesis and cellular
respiration.
AOD B.3.4 Recognize a given formula as either
photosynthesis or cellular respiration.
What Do You Know?
Complete “Before Reading”
portion of Photosynthesis
Anticipation/Reaction Guide.
Section 8-1
• Are plants autotrophs,
chemotrophs, or heterotrophs?
• Energy can be found in many
forms: light, heat, electricity,
chemical bonds.….
• Which form(s) is(are) used by
plants?
• ATP (adenosine triphosphate)
– composed of adenine, ribose,
and 3 phosphate groups:
• ATP is converted to ___, ____,
and ____.
Source:
http://faculty.ccbcmd.edu/bi
otutorials/energy/adpan.html
• Cells only store enough ATP for
a few seconds of activity:
active transport, synthesis of
proteins or nucleic acids,
movements within the cell,
etc..
• ATP is great for transferring
energy, but not storing it.
• Glucose can store 90 times
more chemical energy than
ATP.
Section 8-2
• What do plants need to carry
out photosynthesis?
Water (H2O), carbon dioxide
(CO2) , and sunlight --- These
are called reactants.
• What do plants produce in
photosynthesis?
Glucose (C6H12O6) and oxygen
(O2) --- These are the
products.
Important Historical
Discoveries
• Jan van Helmont (1643):
– Common belief: plants took
material out of the soil to grow.
– Van Helmont grew a tree for 5
years. By comparing the mass
of the dry soil and seedling to
the mass of the soil and small
tree, he concluded that most of
the gain in mass came from
water.
• Joseph Priestly (1771):
– Put a lit candle under a bell jar. What
do you think happened?
– Determined the air in the jar was
“injured”.
– Wanting to see the effects of “injured
air” on living material, he placed a mint
sprig under the jar for a few days.
– When it remained green, he relit the
candle, and it remained lit for a while.
– He concluded the plant “cured” the
injured air.
– What actually occurred?
• Jan Ingenhousz (1779):
– Repeated Priestley’s experiments
using aquatic plants
– Found the plants only produced
gas bubbles when the plant was
exposed to sunlight
– http://www.reading.ac.uk/virtua
lexperiments/ves/preloaderphotosynthesis-full.html
• Melvin Calvin (1948):
– Traced the path taken by carbon
to form glucose in plants.
Photosynthesis Equation
6CO2 + 6H2O
sunlight
C6H12O6 + 6O2
Entrance Slip: Which scientist is
responsible for the discovery of
the different parts of this
equation?
Water Weed Lab – Virtual
Photosynthesis Inquiry
• http://www.cbsd.org/sites/teacher
s/hs/mgleicher/Class%20Documen
ts/Labs/Lab%20%20Water%20Weed.pdf
• Complete lab write-up in your
lab notebook.
• See if your results match up
with the information found on
p.207 of your textbook.
Lab Review
• What color of light will NOT
produce photosynthesis in
plants?
• WHY?????
• Green light is not ABSORBED
by plants. WHY NOT???
• Why are leaves green?
• Why do leaves turn red, yellow,
and orange in the fall?
Spinach Chromatography
Source:
http://www.chemistryl
and.com/CHM130Field
Lab/Lab5/Lab5.html
Section 8-3
• Photosynthesis Overview handout
• Photosynthesis – Biology in a Few
Minutes:
http://www.youtube.com/watch?v=BeUmj8d6
Mag&feature=related&continue_action=afvxnC
ArL3KfYDYfH0vIq5jDaERLtzjb5GDbVUH6nVH6t
BB8lP3QfqliBotcIa747RJlWQzLFT4nhJ_U2URLgl
OUUOSynR1CEMIXwl7BHPA=
• Photosynthesis (BozemanScience):
http://www.youtube.com/watch?v=g78
utcLQrJ4&feature=relmfu
Inside a Chloroplast
• Thylakoids:
– saclike photosynthetic
membranes
– Arranged in stacks called grana
• Photosystems:
– Clusters of chlorophyll and other
pigments
– The light-collecting units of the
chloroplasts
2 Photosystems
• “Light-dependent reactions”:
– Take place in the thylakoid
membranes
– Requires: light and H2O
• Photosystem II:
– Light activates/energizes
electrons, which then enter the
electron transport chain.
– Electrons are replaced by H2O, as
it breaks down into 2 e-’s, 2 H+’s,
and 1 oxygen atom.
Electron Transport Chain
• Light hitting chlorophyll excites
electrons, causing them to gain
energy.
• Electron carriers take these
electrons from the chlorophyll
to other molecules in…….
• Photosystem I:
– Light energy reenergizes the
electrons
– e-’s cause more H+ to be pumped
into the thylakoid lumen, making it
positive, and stroma negative.
– NADP+ can hold 2 e-’s and H+, and
become NADPH, storing energy.
– H+ is transported back outside the
membrane, in an effort to
reestablish equilibrium, by a
protein called ATP synthase,
converting ADP to ATP.
Photosystems I and II
http://nathanielzhu.hubpages.com/hub/Understanding-LightDependant-Photosynthesis
Electron Transport Chain
• http://www.mhhe.com/biosci/genb
io/biolink/j_explorations/ch09expl.
htm
• Recap:
– Light-dependent reactions use
____, ___, _____, ____, and
_____.
– They produce high energy ____
and ______, and release ______
as a waste product.
Calvin Cycle
• Light-independent (AKA,
Calvin cycle)
– Take place in the chloroplast
stroma – fluid-filled space
outside the thylakoid
membranes
– Requires CO2
– Uses the high-energy products
of the light-dependent
reactions! (?????)
• CO2 from the air combines with 5carbon sugars to form 3-carbon
sugars.
• ATP and NADPH convert these
sugars to higher energy sugars.
• 2 of these sugars form the 6carbon glucose molecule and
other compounds needed for plant
metabolism and growth.
• Other 3-carbon sugars are
converted back to 5-carbon to
repeat the cycle.
Calvin Cycle Review
• If ATP’s energy is used, what
does the ATP become?
• NADPH is converted back to
_____.
• Is light used in the Calvin
cycle?
• What atmospheric gas is used
in the Calvin cycle?
• What are the end products?