1) Photosynthesis is a life-sustaining process that occurs in plants, algae, bacteria and some animals through various mechanisms like oxygenic photosynthesis, symbiosis with photosynthetic organisms, and stealing genes from algae. 2) It involves the light and dark reactions - where light reactions use solar energy to produce ATP and NADPH, and the dark reactions use these to fix carbon and produce sugars like glucose. 3) Photosynthesis emerged over 2 billion years ago and was first developed by cyanobacteria, changing the atmosphere by producing oxygen and allowing the evolution of aerobic life. It remains a crucial process providing food and oxygen for most living things.

1. Life sustaining Photosynthesis processes 1
Sea Wif’s Biosphere
Goddard space flight center - Wc – Public domain
Photosynthetic animals !
Emereld Elysia chlorotica Acyrthosiphon
Solar powered green Sea Slug Photosynthetic insect-Pea Aphid
Karen N .P etal– Wc – cc Shipher Wu.GWLin – Wc – cc
Steals genes from Vaucheria algae Uses light& carotenoids for ATP

2. Life sustaining processes 2
The only Photosynthetic vertebrate Solar powered Hornet
Spotted Salamander Ambystoma Vespa orientalis
D.Gordon .E. Robertson - Wc – cc Gideon pisanty – Wc – cc
Symbiotic with Oophila algae Converts light into electricity
Photosynthetic protozoa
Euglena Paramecium
Green with its own chlorophyll Green with symbiont algae
Rogelio morena –Wc – Public domain Anatoly Michaltsov – Wc - cc

3. Life sustaining processes 3
Hydra virdissima Didemnum molle
Green by symbiosis with Chlorella Symbiont with Prochloron
Peter Schuchert – Wc – cc Bernard Du Pont – Wc – cc
Corals Nudibranch Pteraeolidia
Symbiosis with Zoozanthelle Symbiosis with Algae
USFWS – Flickr – loe.org- CC by 2.0 Richard ling –flickr - Wc - cc

4. Life sustaining processes 4
Oxygenic photosynthesis Symbiosis with plants
Daniel Mayer .Yerpo– Wc - cc Somepics – Wc - cc
In plants
Light reactions within Thylakoid membrane
Somepics - Wc - cc

5. Life sustaining processes 5
Z scheme
Bensaccount – Wc - cc
Calvin Cycle
Light independent reaction
Mike Jones -Wc – cc

6. Life sustaining processes 6
Bacterial anoxygenic photosynthesis Purple bacteria
Lithium byproduct - Wc - cc kOch StudiO.Wc. public domain
Purple Sulfur bacteria Nitrosococcus Rhodopseudomonaspalustris
Askmicrobiology.com Cinti - microbewiki.kenyon.edu
Organisms with multiple options !

7. Life sustaining processes 7
Photosynthesis
Oh ! What a phenomenon!
Blessing for some
Curse for others
Curse ? Oh Yes !
Long long ago when it began
almost 2 billionyears ago, be certain
mass extinction it did cause
of the methanelovingthe then forms
Blessing ! Yaw
By utilizing sun rays and chlorophyll
the whole sky it did fill
with oxygen - that enabled
oxygen lovingones to evolve & thrive
Changing the world for all timeto come
Sincethen
It is going on & on
In all the worlds living greens
Of Plantae,Protista, bacterialdomains

8. Life sustaining processes 8
And till date
It is acting as the ultimate
‘Bread provider’ for all fellows
‘ Tom dickand harry’
as the sayinggoes
for
somedirectly –for instance
the plantsand theirkith & kin
othersindirectly-for example
the animals and theirbrotheren
throughthe famousfood chain
In plants
Actingthrough
pigmentproteincomplexes
excitingtheirmolecules
by the energy sun rays carry
Oh How !
By usingantennas
to catch photons of sun rays

9. Life sustaining processes 9
and passing them on
to an actioncenter, striping
an electronfrom each molecule
and passing it on
to the nearest receptor molecule
simultaneously
passing energy to activate Mn complex
at PSII ,which binds 2 moleculesof water
before splitting them to replenish chlorophyll
moleculeswith electronsfrom water
Interestingly
Breaking water intotwo this way requires
energy of 4 photons & catalysisby Mn complex
for releasing 4 e-
, 4p+, &1 O2
Further
excited electrons rush downhill
‘hopping’!‘jumping’!along the series of ‘hills’
of pigmentproteincomplexes
embeddedin the Thylakoidmembranes

10. Life sustaining processes 10
like
pairs of littlegirls runningthrough
a seriesof steps on the slope of a steep hill!
And
fast flowing excitedelectronsstream
passing through the electrontransportchain
creates a potentialdifference, a proton
gradient acrossthe thylakoidmembrane
The resultantpmf rotatesthe ATP synthase
an efficient enzymeand a motor machine
Through
this molecular motor the protonspass
speedilyfrom lumen intostromatalside
and ensurephosphorylation of ADP
resultingin the formationof ATP
Meanwhile
electronsgainmoreenergy at PS I
and end up at NADP enabling it
to pickupH+
forming NADPH

11. Life sustaining processes 11
in stroma(in non cyclicvarietyof
the activity)
Thus
the couplingof electron transport
and pmf produces high energy
chemical currency
in thesetwo forms
But
this is only half of the story
for the second part of the drama
is yet to be played out in stroma
where RuBp & Rubisco enter the scene
The
Rubiscocatches incomingCO2 ,
fixes C from it into RuBp
givinga kickstart to Kelvin cycle
In
the next few steps NADH & ATP
provideenergyfor the cycle to roll on

12. Life sustaining processes 12
It
results in production of H2 O and
3C compounds-someof which go
on to regenerateRuBp and others go
further ahead to generate 6C Glucose.
We
know Glucoseis very versatile;
is easilyconvertiblein starch,sugar
and other products;Is also essential
for fuelingrespiration in us all O! bhai
It
is no wonder photosynthesisprovides
both O2 and glucosefor lifeto survive;
and by absorbingCO2 & releasing O2
in atmosphere enables us to live
in a healthycheerfulenvironment
Technically
Coupling of electrochemicalgradient
with pmf is one of its speciality ;But

13. Life sustaining processes 13
What
makes us wonder reallyis that
it was discovered and startedfirst by
simple looking but reallyclever bacteria–
Cyanobacteriato be precise,
ages ago - in the hoarypast.
Thereafter
Protistarose and became standardbearer
and red & blueAlgae kept the flag flying high
even someprotozoaadoptedphotosynthesis
and later even a few animalstriedit out.
Perhaps
One of the most interestingexampleis of
some molluskssuch as slugs likeElisia
which steal genes and others which eat the
prey but save chloroplastsfor use.
Stillothers
Insects likepea aphidproduceCarotenoids
to carry on photosynthesis .

14. Life sustaining processes 14
And
Clever purplebacteria developedmany
techniques to be able to photosynthesise.
In the
MeanwhileSymbiosisbetween different
organisms was changing the bio world
and Oxygenic photosynthesis emerged
as major Lifesustainingprocessmuch
beforethe evolution of wiseman
homosapiensapien .
Whereas
We men – the most intelligent species
on earth, havelearnt onlyrecently
How to cook food by using solarenergy.
Oh !
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