Photosynthesis – Part I
Spring 2013 - Althoff Reference: Mader & Windelspecht Ch. 7)
Lec
07
Definitions
• Photosynthesis converts ____________ into the
________________ of a ________________
• Photosynthetic
Organisms
• Process of
Photosynthesis
Plants
• ____________ = photosynthetic organisms
that produce their _______________
examples: ________________
________________
________________
• Autotrophs = _______________
The opposite of AUTOTROPHS are…
• _______________ = ____________
…they cannot make their own food…aka
____________________ carbohydrates.
Algae
Cyanobacteria
• Heterotrophs, as do autotrophs, use
___________________ produced by
photosynthesis as a source of building
blocks for growth and repair…as well as a
source of chemical energy for __________
work.
_________________
_________________
Photosynthesis by product….
Fungi
=
___
Insects
Value to all organisms
• Carry on
____________
____________
Mussels
Birds, Fish,
Mammals, etc.
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Besides the O2 “byproduct” of
photosynthesis…there are other benefits to
humans:
Photosynthesis takes place in the “green”
portions of plants (aka leaves)
• For flowering plants (most of what is on
earth), ____________ tissue is present
that specializes in photosynthesis.
mesophyll
Chloroplast
Actual chloroplast
~37,000 x
•
•
•
•
•
Building materials (think lumber)
Fabrics (think cotton)
Paper
Pharmaceuticals
Aesthetic value (think flowers)
Entry of raw materials for
photosynthesis….
Top of leaf
• CO2 in air enters
through ________
• H2O in soil enters
through _______,
then up ________
______ (aka vein)
• CO2 and H2O,
once in the leaf,
________ into
_______________
mesophyll
bubbles
from Elodea
leaves
Chloroplast structure
• ___________
___________:
outer and inner
• __________ semifluid interior
• __________ –
flattened sacs
• _______ (gramum
pl.)– stacked
thylakoids
double membrane
O2
2
Grana close up….
Thylakoids
thylakoid
membrane
thylakoid
space
independent
thylakoid
in a
granum
overlapping
thylakoid
in a
granum
Thylakoids and Stroma
• The __________________ actually
contains the chlorophyll…and other
pigments capable of absorbing solar
energy.
• The ________ contains an energy-rich
solution where CO2 is first attached to an
organic compound…then reduced to a
carbohydrate.
• Spacing of thylakoids thought to be
connected to the ____________________
thylakoids within a chloroplast….
• The result is a _________________
…providing a tremendous amount of
surface area for photosynthesis to occur.
Photosynthesis: The Process
• The equation implies that photosynthesis
involves ________ (=oxidationreduction)…and the movement of
electrons from one molecule to another
• This means a) CO2 gains an electron and
b) H20 loses one….a ____ is “transferred”
Photosynthesis: The Process
Two Important Coenzymes
• In photosynthesis, solar energy is used to
generate the ___________________ the
CO2 to a __________________.
• ________ is the coenzyme of oxidationreduction active during photosynthesis.
When reduced it accepts 2 electrons and
and 1 hydrogen atom to become _______
• When NADPH oxidizes, it give up its
electrons
• Keep in mind, this carbohydrate
represents the _______ produced by land
plants, algae, and cyanobacteria that
feeds _____ the biosphere.
• NADP+
+
2e-
+ H+
 NADPH
3
Back to the Elodea leaf…
• What molecule
supplies the
electrons that
reduce NADP+
during
photosynthesis?
Two Sets of Reactions
• _________________—so named because
they only occur when solar energy is
available. Associated with “_______”
energy
• __________________________—named
for Melvin Calvin who discovered the
enzymatic reaction that reduces CO2.
Associated with “____________” energy
The _____________
_________________
that is split!
CALVIN CYCLE
REACTIONS
LIGHT REACTIONS
O2
CH2O
Light Reactions
Light Reactions
• Sunlight/solar energy
__________ by
chlorophyll that drives
photosynthesis
• Solar energy “________”
the electrons that move
down an _________
_______________. As it
does, energy released is
captured as _____
molecules.
Mader Fig. 6.12 p114
Calvin Cycle
To summarize….
• Solar energy  _________________
(ATP, NADPH)
• But, O2 is given off, too
• Enzymes present speed up the reduction
of CO2 during __________________
• Occurs in the ____________________ of
the chloroplast stroma
• When reduction results in
carbohydrate…it can later be converted
to glucose…this is achieved by using
ATP and NADPH _____ the light
reactions
O2
4
Calvin Cycle Reactions
To summarize….
• _________ energy __________ energy
(ATP, NADPH)
(carbohydrate)
CH2O
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