6. PHOTOPHOSPHORYLATION:
In the process of photosynthesis,
the phosphorylation of ADP to ATP
using the energy of sunlight is
called photophosphorylation.
TYPES OF
PHOTOPHOSPHORYLATI
ON
There are two types of
photophosphorylation
1.Cyclic photophosphorylation
2.Non-cyclic photophosphorylation
7. CYCLIC PHOTOPHOSPHORYLATION:
• “The returning back of the same excited
electron to excited chlorophyll by producing a
molecule of ATP is called cyclic
phosphorylation”.
8. MECHANISM:
In bacterial photosynthesis, a single photosystem is
• involved.
When an electron is energized by absorption of light, it is ejected from the
photosystem reaction centre.
The electron then passes down through an electron
• transport system, and finally to the reaction centre.
The energy released during this electron transport is used to produce ATP.
Since the excited electron returns to the reaction centre, this mechanism
for making ATP is called cyclic photophosphorylation.
9. STEPS:
• First of all P700 of the photosystem 1 absorb light.this light drives
electron from P700 to primary electron acceptor.it produce
electron hole in the chlorophyll.
• The primary acceptor of electron of PS1 transfer electron to Fe-S
protein.
• Fe-S protein transfer electron to ferrodoxin.
• Electron transfer from ferodoxin to cytochrome complex.
10. CONTI………………
• Finally the cytochrome complex return theses electron to
excited chlorophyll of P700.
• A molecule of ATP is produced during this transfer of
electron through ETC by chemiosmosis.
• The NADH is not produce and oxygen is not released.
