The document discusses photosynthesis and purple sulfur bacteria. It explains that photosynthesis converts light energy to chemical energy by reducing carbon and hydrogen compounds and releasing oxygen. It describes the structures and pigments involved in photosynthesis, including the two photosystems that generate ATP and NADPH. Purple sulfur bacteria are anaerobic bacteria that use sulfide or sulfur instead of water as an electron donor for photosynthesis. They are found in places like hot springs and produce sulfur globules inside or outside the cell.

4.  Photo means light and synthesis means to
put together
 The process by which radiant energy(light) is
converted into chemical energy by
autotrophic organism
 Energy poor inorganic oxidized componds of
C and H are reduced to energy rich
carbohydrates and oxygen is released

5.  Van helmont’s experiment (1643)
 Priestley’s experiment (1771)
 Ingenhousz’s experiment (1779)

6.  Reducing environment changed to oxidizing
environment – oxygenic photosynthesis
evolve

8.  Plant metabolism
 Energy production
 Food chain
 Composition of air

9.  Location
in mesophyll cells of leaf
 Structure
double membrane bounded organelle
having thylakoids and grana
 Size
2- 10μm

10.  Pigments captures light energy for
photosynthesis
 In plants
 Carotenes(orange)
 Xanthophyll(yellow)
 Phaephytin-a(gray brown)
 Phaephytin-b(yellow brown)
 Cholophyll –a(blue green)

11.  Cholorophyll –b (yellow green)
 In cyanobacteria(phycobilliprotein)
 In algae(cholorophyll)

13.  Light reaction are light dependent reaction
which use light directlly
 Formation of ATP AND NADPH
 NADPH provides energized electron while
ATP provides chemical energy for the
synthesis of sugar

15.  Photosystem -I (p700)
 Photosystem –II (p680)
 Antenna complex
 Reaction centre (cholorophyll a molecules ,
primary electron acceptor, electron carrier of
electron system)

16.  Exciation of electron in PS-II
 Photolysis
 Electron transport chain(ETC)
 ATP synthesis
 Excitation of electron in PS-I
 NADPH reduction

18.  Also called short circuit cycle
 NADPH level rise
 ATP level rise
 No oxygen will release

20.  Mechanism of ATP synthesis(cyclic + non-
cyclic)
 Uses membranes for coupling redox rex.
 Diffusion of H+
 Energy of electron makes ATP

28.  Scientific name- Chromatiales
 Rank- order
 Two families
 (i) Chromatiaceae(internal sulfur globules)
 (ii) ecthiorhodospiracea(external sulfur
globules)

30.  Group of proteobacteria (phylum of gram
negative bacteria)
 Anaerobic or microaerophillic
 Lives in hot springs
 Favourable place is meromictic lakes
(which are permanently stratified having
denser saline water at bottom and less
dense fresh water at surface)

31.  . If sufficient sulfate is present to support
sulfate reduction, the sulfide, produced in the
sediments, diffuses upward into the anoxic
bottom waters, where purple sulfur bacteria
can form dense cell masses, called blooms,
usually in association with green
phototrophic bacteria

33.  Source of electron
 P.S.B and P.N.S.B
 Electro –ve and electro +ve reduction
potential
 Source of light
 Location of reaction

34. Why we need this cyclic flow
of electrons in light reaction?

35.  Photoreactive centers
 Photopigments or light harvesting molecule
 Types of electron carrier
 embedded electron carrier
 mobile electron carrier

39.  Anaerobic, anoxygenic,
photoautotrophic photosynthetic
bacteria
 All species are non-motile
 Cells of different species are
spherical, curved, rods or ovoid
 Can survive in extreme conditions
 Found in deep oceans
 use sulfide or sulfur as a source of
reduction for photosynthesis
 Sulfur produced from sulfide, but
never inside the cell

40.  Reaction Centre:
they use type-1 reaction centre
P840 as it absorbs the light of 840nm.
 Electron Acceptor:
Electron acceptor molecules
resides at about 0.0 reduction potenial in purple
bacteria while in green bacteria they are at -0.6
reduction potential that is much more than
NADH. This is the reason that NADH is reduced
in green bacteria but not in purple sulfur
bacteria

41.  6CO2 + 12H2S C6H12O6 + 12S
+ 6H2O + energy
Light