Photosynthesis - General
The following points describe the significance and
relationship of photosynthesis to life on earth.
- Photosynthesis begins the carbon cycle by
fixing CO2 (carbon dioxide in the
- It has 2 major metabolic components: the light
reactions and the "dark" reactions
- The overall equation for photosynthesis
6 CO2 + 12 H2O + energy
C6H12O6 + 6 H2O + 6
- This equation leaves out many important
details such as:
- where does the O2 gas
come from? (water)
- how is light energy converted into chemical
bond energy? (see light reaction and "reaction"
- The oxygen released as a by-product has a
major impact on the bioshpere. Today's atmosphere would not have
21% oxygen if not for photosynthesis.
- Three kingdoms have photosynthetic autotrophs
- monera - cyanobacteria
- protista - algae
- Photosynthesis is endergonic G
= +686 kcal/mole