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Engineering HSC and IIT-JEE Mains and
advanced videos. Hello students today
will be studying chapter
photosynthesis in that we'll be
studying cyclic photophosphorylation
when I say cyclic it means it will move
in circle in order basically I'm gonna
say for the phosphorylation it means use
of sun's energy to make glucose molecule
or type of photosynthesis in cyclic
photophosphorylation will be studying
how sun's energy falls on various
electron acceptors in cyclic man.
cycling for phosphorylation when
cyclic photophosphorylation there is a
pigment system employed remember
photosynthesis equation okay now doing
cyclic photophosphorylation there is a
reaction center and this reaction center
is present inside grana the structure of
chloroplast inside grana there will be
reaction centers there are two reaction
centers PS one for the system one and
for the system - today will be studying
off photosystem one of PS own once the
reaction center of PS one is of p700 so
then sun's energy falls on the reaction
center of T 700 what happens is the
reaction center gets excited and once
the reaction center gets excited its
parts the electron through various
electron acceptors and this electron
acceptors are in series they are
basically cyclic and during this process
certain ATP molecules are formed which
could be used during the back reaction
the electron acceptors which are present
during cyclic photophosphorylation an
FRS that is ferredoxin reducing
substances cytochrome B 6 phytochrome f
ferredoxin during cyclic
photophosphorylation basically two ATP
molecules are generated and this two ATP
molecules organ say adenosine
triphosphate molecules are used in the
back reaction or in Calvin cycle or you
can say in black man's reaction now how
does ATP breaks down ATP is adenosine
triphosphate and then you mean energy
from ATP you need to take that one
phosphate so the reaction is ATP when it
is broken down it forms adp plus P
doing cycling for the phosphorylation
when it's safe for the phosphorylation
it means photons or sun's energy I'm
gonna say phosphorylation it means
breakdown of ATP that is adenosine
triphosphate cyclic photophosphorylation
basically uses pigment system 1 or PS 1
which has reaction center of P 700 so
what happens to the reaction center
whenever the reaction center energy or
light molecules form we all know that
there are pigments which are present
inside granite
and this pigments are chlorophyll a
chlorophyll P carotenoids and
xanthophyll now chlorophyll a is the
master pigment whereas rest of them are
accessory pigments so this chlorophyll a
absorbs sun's energy and it gets excited
and due to this excitement of this
reaction center of chlorophyll a energy
rich electrons are passed through
various electron acceptors
now during this transfer of electrons or
during cyclic photophosphorylation extra
energy is used to bind a baby that is
adenosine diphosphate to form ATP that
is a designed triphosphate okay one
cyclic photophosphorylation is called a
cyclic photophosphorylation because
electrons completes a full cyclic
pathway or they move in a proper circle
doesn't break anyway
the cycle is a complete cycle without
pauses so let us see how electrons move
in cyclic photophosphorylation the
reaction Center which is of p700 absorbs
sun's energy in the form of photons
now when sun's energy falls on the
reaction center in the form of photons
the reaction center gets excited and it
emits electrons now the first electron
acceptor is fr-s ferredoxin reducing
substance from FRS the electron is
passed to empty that is fara oxen from
ferredoxin it is passed to cytochrome B
6 and from cytochrome B 6 it is passed
to cytochrome F and the last electron
acceptor is +2 Simon so as you can see
the electrons start moving from the
reaction center and they move a cyclic
wave without breaking the chain that is
one cyclic photophosphorylation
is called a series of electron acceptors
which move in cyclic order without
breaking since the electron that starts
from P 700 and gets back to P 700 so the
electron is returned back to P 700 the
significance of cyclic
photophosphorylation could be that there
are two ATP molecules
generated as you can see one ATP
molecule that is generated and another
ATP molecule that is generated I hope
you are clear with the concept of cyclic
photophosphorylation
