Photosynthesis
Photosynthesis occurs in 3 main stages: energy is captured from sunlight,
then
it’s converted into chemical energy and stored in organic
molecules.
Photosystems are light harvesting units of the thylakoid
membrane. Each
photosystem has four hundred pigment molecules. A photon hits
the pigment
molecules and travels through each molecule and then reaches the
reaction center
as shown in figure 1-1. The thylakoid membrane has two
photosystems, photosystem
1 & 2. The reaction center in photosystem 1
is called P700 because this
pigment is best at absorbing 700 mm light.
Photosystem 2’s reaction center is
called P680 because it is best at
absorbing 680 mm light. Calvin Cycle The
Calvin cycle begins by
incorporating Co2 from the air into molecules in the
chloroplast. This action
is called carbon fixation. The next thing it does is
add electrons to the
fixed carbon to make it carbohydrate. The power of the
Calvin cycle comes
from NADPH. The Calvin cycle also needs energy from ATP,
which is generated
by light reactions. This is reaction is called "dark
reactions" because it
does not directly need light to work. So basically all
the Calvin cycle does
is make sugar with out light but with help from ATP &
NADPH.