PHOTOSYNTHESIS Notes
KEY WORDS/
QUESTIONS
Who:
NOTES
All plants, and some specialized bacteria known as
cyanobacteria.
Where:
Above is a cool diagram showing exactly where these
processes are located in the plant. Photosynthesis can
be broken down into two main parts: Light Dependent
Reaction and the Light Independent Reaction.
Light Dependent Reaction (LDR): Occurs on the
thylakoid membranes since it involves pigments and
proteins, and these reside on the phospholipid bilayer
of the thylakoid. (Aargh...all that vocab!)
Light Independent Reaction (LIR) NOT DARK REACTION!!!:
Occurs in the stroma of the chloroplast, because it
uses special enzymes and molecules and that is where
they reside.
Why:
For plants: To make energy in the form of sugar
(glucose) and ATP (adenosine tri phosphate)
ADP (adenosine di phosphate)
AMP (adenosine mono phosphate)
A
-
P – P - P
For humans: so we can get energy from eating the
plants that have made the sugar and ATP
PHOTOSYNTHESIS Notes
How:
Part I: _Light
Dependent
Reaction
Occurs where in
the leaf? On the
membranes of the
thylakoid discs
in the
chloroplast
Key parts to review:
*Chlorophyll molecules (seen during the chromatography
lab) are those molecules that trap the photons.
*Photosystems: two separate ones to respond to
different wavelengths of light, thus enhancing the
plants ability to make the most use out of the visible
light range.
*PSII’s job is to pass the electron via the carriers
and as a result, build up a hydrogen ion concentration
difference that will eventually lead to the production
of ATP.
*PSI’s job is to take more electrons and produce NADPH.
(Note: the “H” comes from the splitting of water and
the NADPH is a glorified dump truck that delivers the H
to the right place)
*Purpose of splitting water is to replace the electrons
lost from the initial photon excitement of the
chlorophyll in PS2.
*OVERALL PURPOSE OF THE LDR: make the molecules
necessary for the LIR to occur.
PHOTOSYNTHESIS Notes
How:
Part 2:
_________________
____
When:
Don’t worry! I’m not having them memorize the names of
each of the molecules! Only RuBP and Rubisco. I like
this diagram b/c it will help them to see how the
enzyme Rubisco “fixes” the carbon dioxide to RuBP
forming an unstable six carbon compound (not shown)
which breaks apart immediately into the three carbon
compound (phosphoglycerate). They can see how the ATP
and NADPH come in to help modify and reform the carbon
compounds into an eventual glucose molecule and the
regeneration of RuBP
LDR: occurs only during the daylight hours since it
requires the photons to function.
LIR: can occur regardless of the status of light, just
as long as there is ATP and NADPH to run the Calvin
Cycle.
http://www.cst.cmich.edu/users/baile1re/bio101fall/enzphoto/photoanima.htm
#
http://faculty.nl.edu/jste/calvin_cycle.htm
http://iws.ccccd.edu/rorr/1406%20Spring%2007/Chp10CalvinCycle_A.swf