Photosynthesis
Chapter 7
Photosynthesis=
6CO2+12H2O--------C6H12O6+6H2O+6O2
Who photosynthesizes?
Cyanobacteria
Algae
Plants
Flowering Plants
Where does photosynthesis occur?
-leaves (vegetative structures)
Leaf Anatomy:
-Palisade Mesophyll tissue =
-Spongy Mesophyll tissue =
-Stomata=
-guard cells =
-Chloroplast:
thylakoid=
Chlorophyll=
grana=
stroma=
What is involved in Photosynthesis?
1. Visible Light =
ROYGBIV
-Photon=
-Waves & Color
-nanometers (nm)=
2. Pigments
-reflection & absorption
2 primary types of plant pigments:
1. Carotenoids=
2. Chlorophylls=
-chlorophyll a & b
*Why does a plant look green?
*What colors of light do plants use?
*Why do leaves change colors?
Photosynthetic Reactions
Solar e + 6CO2 + 6H2O  C6H12O6 + 6O2
-Redox Rxn: -CO2 is reduced
-H2O is oxidized
Two Sets of Rxns (two steps):
Step 1.) Light Rxn=
-light e
-ATP & NADPH
Step 2.) Dark Rxns (Calvin Cycle) =
-CO2
Photosynthesis in Detail:
Step 1: The Light Reaction
-occurs on the thylakoids
-involves photosystems =
-photosystem I (PS I)
-photosystem II (PS II)
-electron acceptor =
-photolysis=
-electron transport chain
-involves two pathways for e- to flow
Noncyclic Electron Flow Light Rxn:
-occurs in plants & algae
- e- originate with H2O
and end with NADPH
-both photosystems are involved
-Noncyclic Photosphosphorylation
Cyclic Electron Flow Light Rxn:
-occurs with all photosynthesizers
- e- originate with PSI and return to PSI
-only PSI is involved
-only ATP –not NADPH is produced
-Cyclic photophosphorylation
Step 2: The Dark Reaction =Calvin Cycle
=series of rxns that produce CHO and then
return to the starting point.
-occurs with both cyclic & noncyclic
light reactions (all photosynthesizers).
-uses ATP & NADPH to convert CO2
into glucose.
-occurs in the stroma of the chloroplast.
-occurs 6 Times to produce 1 glucose
Composed of 3 Phases of rxns:
1. CO2 Fixation
-RuBP
2. Reduction of CO2
-glucose formed here
-ATP & NADPH used here
3. Regeneration of RuBP