It is a process in which plants use
Sunlight, chlorophyll, CO2 & H2O to
           synthesize food
   6CO2+12H2O          ...
SITE OF PHOTOSYNTHESIS
Chlorophyll pigments are
present in a cell organelles
called plastids-chloroplast
Four 5-membered rings, called pyrolle
  rings
• central core oF magnesium.
• a side chain, called the phytol chain,
  exte...
pigment is a substance that
absorbs light oF diFFerent
wavelengths.
chlorophyll absorbs light in the
violet and blue wav...
• CAROTENOIDS
• CHLOROPHYLL




                           •   They absorb light of different
                            ...
photo system          photo system ii
  i(psi)                (psii)
• it includes chl a   • it includes chl a
  with maxi...
There are two steps of
  photosynthesis
• Light reaction

• Dark reaction
• Chlorophyll absorbs light energy in the
  form of photons, get excited and release
  electron.
• Electron passes through...
Formation oF atp in
   the presence oF
        light is
  photophosphoryl
         ation.
 ADP+Pi          ATP
  it occurs...
• it includes two photo systems-psi and psii.
• when psii(p680)absorbs light , excited and its
  electrons are transFerred...
PQ
     Cyt b6
              Cyt f
                      PC
• splitting oF water in presence
  oF light
  h 2o          2h + + 1 / 2 o 2 + 2e -

• the electrons generated in
  this p...
When chloroplast is illuminated with light greater than
680nm,only PSI is activated, as it has a maximum absorption
at 700...
• carbon dioxide is reduced to
  carbohydrates (carbon Fixation).
• carbon Fixation occurs in the
  stroma oF chloroplast....
it consists oF three phases.
• carboxylation
• reduction
• regeneration oF rubp
            carboxylation -
    the First ...
12 molecules of PGA is converted into 12 molecules of 1,3-di-
phosphoglycerate and then reduced to phosphoglyceraldehyde
(...
C6H12O6
–Hatch and Slack Pathway:
This pathway of carbon fixation occurs in plants
like maize, sugarcane, pearl millet and amaran...
Phospho-enol-pyruvate(PEP) is the CO2 acceptor ,
present in the mesophyll cells and the reaction is
catalyzed by the enzym...
C4 plants are special they       tolerate higher temperature, they show a response to highlight
intensity , they lack the ...
Characteristics                     C3plants C4plants Choose from
the Calvin cycle Cell type in                         Me...
rubp +o2

rubp+co2




   2 x 3pga
                 pga + phosphoglycolate
{calvin cycle}
                   {photo respir...
• At high temperatures and limited CO2 supply Rubisco enzyme
binds with O2 instead of CO2 in C3 plants and enters in the c...
light-the chlorophylls absorb
mostly the blue and red regions oF
the spectrum. the rate oF
photosynthesis increases at the...
•the rate oF photosynthesis increases
   with increase in temperature up to a
    maximum oF 30oc. however the rate
  star...
• The rate of photosynthesis increases with an increase in
  carbon dioxide concentration up to a certain level. Beyond
  ...
• The rate of photosynthesis is slow in water
  deficient conditions because of two
  factors.
• 1. Under water deficient ...
To make a temporary stained mount of lily and petunia leaf
  and count the number of stomata on upper and lower
          ...
Photosynthesis
Photosynthesis
Photosynthesis
Photosynthesis
Photosynthesis
Photosynthesis
Photosynthesis
Photosynthesis
Photosynthesis
Photosynthesis
Photosynthesis
Photosynthesis
Photosynthesis
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Photosynthesis
Photosynthesis
Photosynthesis
Photosynthesis
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Photosynthesis
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Photosynthesis
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Photosynthesis

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Photosynthesis

  1. 1. It is a process in which plants use Sunlight, chlorophyll, CO2 & H2O to synthesize food 6CO2+12H2O C6H12O6 +6H2O+6O2
  2. 2. SITE OF PHOTOSYNTHESIS
  3. 3. Chlorophyll pigments are present in a cell organelles called plastids-chloroplast
  4. 4. Four 5-membered rings, called pyrolle rings • central core oF magnesium. • a side chain, called the phytol chain, extends From one oF the pyrolle rings in the chlorophyll molecule. • chl a and chl b are similar in structure except that the-cho group in chlorophyll a is replaced with –ch3
  5. 5. pigment is a substance that absorbs light oF diFFerent wavelengths. chlorophyll absorbs light in the violet and blue wavelengths an also in the red region oF the visible spectrum oF light. this portion oF the spectrum between 400nm and 700nm is also known as photo synthetically
  6. 6. • CAROTENOIDS • CHLOROPHYLL • They absorb light of different wavelengths and funneled to • I t is a major pigment the reaction centre (accessory converts the light pigments or antennae energy into electrical molecules) energy. • They also protect the chlorophyll from oxidation.
  7. 7. photo system photo system ii i(psi) (psii) • it includes chl a • it includes chl a with maximum with maximum absorption at absorption 700nm(p700)&other at680nm(p680)&oth accessory er accessory pigments. pigments. • they are present • they are present in stroma in the oppressed thylakoids & non regions oF grana
  8. 8. There are two steps of photosynthesis • Light reaction • Dark reaction
  9. 9. • Chlorophyll absorbs light energy in the form of photons, get excited and release electron. • Electron passes through electron transport chain. • NADP reduces to NADPH+ H+ • Energy release in the form of ATP • ADP+Pi ATP
  10. 10. Formation oF atp in the presence oF light is photophosphoryl ation. ADP+Pi ATP it occurs in two ways:
  11. 11. • it includes two photo systems-psi and psii. • when psii(p680)absorbs light , excited and its electrons are transFerred to an electron acceptor molecule. • now psii becomes a strong oxidizing agent and splits a molecule oF water(photolysis oF water).psii restores the electrons From the water molecule • the primary e- acceptor (phepophytin in plants) is reduced. • the reduced acceptor is strong a reducing agent now denotes the e- to an electron transport chain, consisting oF plastoquinone, cytochrome complex and plastocyanin to psi(p700). • p700 is excited by absorbing light and emits electron which is accepted by primary electron acceptor. • the primary electron acceptor is reduced. it
  12. 12. PQ Cyt b6 Cyt f PC
  13. 13. • splitting oF water in presence oF light h 2o 2h + + 1 / 2 o 2 + 2e - • the electrons generated in this process are used to replace the electrons lost by p680 • the protons are used For reducing nadp to nadph. • oxygen is liberated as a
  14. 14. When chloroplast is illuminated with light greater than 680nm,only PSI is activated, as it has a maximum absorption at 700nm,and PSII absorbs at 680nm.remains inactivated. In cyclic only PSI is involved. When it is activated by light, it emits electrons. These electrons are accepted by the primary acceptor, then transfer to ELECTRON TRANSPORT CHAIN i.e. Ferridoxin,Plastoquinone, cytochromeb6&bf and then finally come back to PSI(P700). This downhill movement of electrons from an electron acceptor to P700 results in the formation of ATP from ADP, and is termed as cyclic photophosphorylation. In cyclic photophosphorylation oxygen is not released (as there is no photolysis of water ) and NADPH2 is also not produced.
  15. 15. • carbon dioxide is reduced to carbohydrates (carbon Fixation). • carbon Fixation occurs in the stroma oF chloroplast. • the process makes use oF the atp and nadph produced in the light reaction.
  16. 16. it consists oF three phases. • carboxylation • reduction • regeneration oF rubp carboxylation - the First acceptor oF co2 is ribulose 1,5  biphosphate.6 molecules oF co2 reacts with molecules oF 6 rubp (ribulose bi phosphate) to Form a short lived 6c compound.  the reaction is catalyzed by rubp carboxylase (rubisco).  6c compound breaks into 2 molecules oF 3c- compound i.e.phosphoglyceric acid.  pga is the First stable compound in this pathway.
  17. 17. 12 molecules of PGA is converted into 12 molecules of 1,3-di- phosphoglycerate and then reduced to phosphoglyceraldehyde (PGAL) using ATP and NADPH. Two molecules of PGAL are used for the synthesis of glucose molecule than starch. 10 molecules of PGAL by a series of complex reactions are converted into 5Ccompound,RUBP. The formation of 6 molecules of RuBP needs 6 ATP molecules. Total 18 ATP and 12NADPH is required in the synthesis of one molecule of Glucose.
  18. 18. C6H12O6
  19. 19. –Hatch and Slack Pathway: This pathway of carbon fixation occurs in plants like maize, sugarcane, pearl millet and amaranth. These plants have two types of photosynthetic cells i.e. mesophyll cells and bundle sheath cells (Kranz anatomy). The chloroplast are dimorphic i.e. those in the mesophyll cells are granal and those in the bundle sheath cells agranal.
  20. 20. Phospho-enol-pyruvate(PEP) is the CO2 acceptor , present in the mesophyll cells and the reaction is catalyzed by the enzyme PEP case . The first stable product is oxalo acetic acid (OAA) which is a 4C-compound OAA is converted into malic acid and transported to bundle sheath cells where it is decarboxylated into pyruvic acid . The CO2 librated is used for Calvin cycle in the bundle sheath cells. Pyruvic acid is transported back to mesophyll cells where it converts into PEP. During this conversion 2 ATP
  21. 21. C4 plants are special they tolerate higher temperature, they show a response to highlight intensity , they lack the process called photorespiration and have greater productivity of biomass.
  22. 22. Characteristics C3plants C4plants Choose from the Calvin cycle Cell type in Mesophyll/bundle which takes place sheath/both Cell type in which the initial Mesophyll/bundle carboxylation reaction sheath/both occurs 1.Mesophyll,bundle How many cell types does the leaf sheath. have that fixCO2 2. .Mesophyll Which is the primary CO2 RuBP/PEWP/PGA acceptor? Number of carbons in the 5/4/3 primary CO2 acceptor Which is the first stable PGA/OAA/RuBP/PEP product? Does the plant have PEP Yes/no/not always case?
  23. 23. rubp +o2 rubp+co2 2 x 3pga pga + phosphoglycolate {calvin cycle} {photo respiration}
  24. 24. • At high temperatures and limited CO2 supply Rubisco enzyme binds with O2 instead of CO2 in C3 plants and enters in the cycle of photorespiration. •It involves interaction pf three organelles-chloroplast, peroxisome and mitochondria. • RUBP+O2 Phosphoglycote+PGA • (CHLOROPLAST) •Phosphoglycolate passes through series of reactions and finally forms RUBP. •75% of the carbon lost by the oxygenation of RUBP is recovered and 25% is lost as release of one molecule of CO2. •No doubt it is a wasteful process but it has a useful role in protecting the plants from oxidative damage
  25. 25. light-the chlorophylls absorb mostly the blue and red regions oF the spectrum. the rate oF photosynthesis increases at the lower intensities oF light and decreases at higher intensities. reason: i-other Factors required For photosynthesis become limiting. 2. destruction oF chlorophyll occurs
  26. 26. •the rate oF photosynthesis increases with increase in temperature up to a maximum oF 30oc. however the rate starts decreasing iF the temperature rises beyond 3o0c. •reason: photosynthesis involves number oF enzymes. the Function oF enzyme is maximum at optimum temperature. low temperature inhibits the rate oF photosynthesis as it lowers the activity oF enymes.high temperature inhibits the rate oF photosynthesis as as it denatures the enzymes
  27. 27. • The rate of photosynthesis increases with an increase in carbon dioxide concentration up to a certain level. Beyond that, carbon dioxide concentration has no effect on the rate of photosynthesis. • In C3 plants rate of photosynthesis increase up to 500µl.l-1 but in C4 plants up to300µl.l-1due to two factors: • 1.high availability of substrate for the carboxylation reaction. • 2. reduced photorespiration due to more available CO2to RUBISCO.
  28. 28. • The rate of photosynthesis is slow in water deficient conditions because of two factors. • 1. Under water deficient conditions stomata remain closed to reduce the rate of transpiration. This reduce or stops the entry of CO2 into the leaves. • 2.Reduced water potential.
  29. 29. To make a temporary stained mount of lily and petunia leaf and count the number of stomata on upper and lower surface of epidermis

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