Welcome back to the lecture series in bio
energy so when we concluded the last class
we concluded with the formation of fructose
6-phosphate which is the first key molecule
or sugar molecule and I concluded to the fact
that in the next class we will talk about
how the two major molecules called the starch
or the sucrose our form because these two
formation of these two molecules is essential
about what is the raw material we are getting
to transform these kind of energy-rich molecules
to alcohol or whatever other energy rich products.
So the efficiency or the growth or with what
rate these molecules are formed and what is
the energy requirement for a plant to produce
per unit starch or sucrose or all these energy-rich
molecules is what determines that how much
benefits we can harness from a bio fuel or
from the whole process will it be cheaper
because think of for a minute we went through
so we started the class with the energy dynamics
we talked about the basic energy and then
we moved on to the by energy.
Then we move to the bio resource where from
there on we started talking about the whole
scheme of biomass production and in that process
we have explored the light and dark cycle
of photosynthesis and in the dark cycle by
the time we leave the last class we talked
about the Calvin cycle where the formation
of sugar takes place, so now this in this
whole process of thing you need solar energy
which leads to excitation of the chlorophyll
molecules at for the system 1 and photo system
2then that generates very strong reluctant
like NADPH and weak as well as weak oxidant
as well as we created reluctant like ATP as
well as oxygen as a by-product okay and in
that process we realize that this whole thing
what all input in terms of the solar energy
interms of ATP in terms of NADPH and how much
carbon dioxide is getting transformed so there
has to be a kind of energy map that what is
your input what is your output and what is
the cost involved.
Because whenever we are growing plant now
to add a few other things suppose you are
growing a plot or a curse or hectares of land
with some plant which you believe that you
can transform it into you can transform the
biomass of it into some kind of a very rich
bio film so what you have to take into account
is for example.
So what you have to take account is that particular
plant what is certain things which you are
getting free of cost out here the input why's
your free of cost input is sunlight provided
you are staying in a sunlight rich area but
then water it is a commodity there are places
on our to where it is cheaper yet there are
places on earth where it varies then you need
in terms of growing the plan or the crop / crops
floating okay.
I am just putting energy rich energy plant
or energy crop valuing the fertilizers and
nutrients fertilizers and nutrients now even
if the sunlight there may be a situation you
may do may have to do it in door so you need
different kind of setup in terms of say if
you have to use artificial light okay as well
as so after this you need to spend on plant
protection measures in terms of attack from
pathogen and other microbes.
After all these things what is the output
what you are getting is in the form of a biomass
so these are your of course if you are going
it in someone else's land then you have to
give the soil or the land charges so if you
order add all these things say for example
A if I represented by a or a prime if it is
an artificial light source B which is water
see which is set Soil and land then d this
expenditure and of course for many of the
e then there is an involvement of manual or
machine labor in terms of how big is the form
size.
So that is your f okay so these are all your
expenses so if I have to put the expenses
so these are your expenses, expenses include
a or / a prime plus B plus C which is soil
and land Plus D+ e which is plant protection
measured then you have the f at least now
what you are producing is biomass what is
the form of biomass you are getting that is
what we are going to discuss today either
it will be starch or some form of other simple
carbohydrates like sucrose okay.
Now come the next phase of it which is transforming
them so either at this stage of two options
either you can directly use them for burning
swell okay or you convert them into high-end
so before we move into this part how you the
conversion which will be the next part which
will be taking probably after couple of classes
at this stage we will talk about what is the
currency of biomass in form of in terms of
the starts and the sucrose.
If you see the last class where we end it
this is where we stay.
So the fructose to starch and the sugar and
in that process what is the expenditure of
ATP ADP and the light so today our job will
be at this stage we will talk about we will
not.
So we will talk about what is the light expenditure
you need it how much light it will be needing
for this kind of situation how many photons
what are we are not dealing fertilizers and
nutrients is crock to crop basis we are not
going to deal with this so I will and land
also we are not dealing we'll definitely talk
about how many water molecules on an average
will be needing to make one heck soul or 16
sugar six-carbon sugar and plant protection
measures we are not taking here.
Because that that also varies from plant to
plant and this is also we are not taking so
essentially what we will be dealing today
will we talk about what is the water expenses
what you are having what is the light in terms
of the photons and in this process what all
ATP and NADPH is involved to convert Co2 to
six carbon starch or sucrose okay.
So let us move on so if we talk about the
starch and the sucrose so the starch is nothing
but those of you just recollect back when
we explained about the structure about the
glucose so you can represent glucose something
like this okay it is a six carbon so something
like this someone suck right okay so now these
glucose molecules is this is an individual
glucose I am NOT adding all the functional
groups or anything out there.
So if each one of these glucose molecules
ERG represent glucose okay each of these glucose
molecules are attached to each other like
this in linear chain, so there are two ways
it can join one is called say for example
it is linearly attached like this something
like this which is called 1-4 glycosidic linkage
okay this is one of the ways how this linkage
take this which is a linear- linear chain
long linear chains of molecules yet there
is another way it can form that forms between
two different chains.
Say for example this is if I represent this
as one single chain like this and there is
another chain like this and between the two
chains there are linkages which are called
16 glycosidic linkages what does that one
and four means is so if you start numbering
them this is1, 2, 3, 4, 5, 6 okay similarly
here if I number them 1 2 3 4 5 6 if you see
the bond which is forming here it is forming
between carbon 1 and carbon 4 that is what
represent one of this one to the first one
this one and the four of the second one this
one okay.
So that means that makes it 1-4 glycosidic
because both of them are glucose molecule
like pathetic linkage so see for example there
is a bond which forms between if is not let
me again right to glucose molecule say this
is one glucose molecule sitting here and let
us number them 1 2 3 4 5 6 okay so another
glucose molecule somewhere out here.
With one two three four five six so if there
is a bond which is formed between this one
and this one then those are called 16 microcytic
linkages.
So if we look at what we are essentially doing
plant contains two major storage forms which
we have already talked about one is the starch
and the other one is the sucrose okay, now
if we talk about the starch, starch is basically
stored in the form of starch is like glycogen
very similar to other similar to glycogen
and it is basically you can call this as a
polymer of glucose and most of this polymeric
chain of sucrose consists of1-4 glycosidic
linkages and there is a small fraction small
fraction of 16glycosidic linkages.
Which are present in them so this is synthesized
and stored in the chloroplast so all this
starts molecule what you see so this the genesis
of all these things is from fructose 6-phosphate
to starch Kelvin cycle fructose 6-phosphate.
Look at this molecule so this is converted
into starch or and sucrose.
This is a starch is store in a chloroplasts
now there is a second molecule which is form
which is called sucrose, sucrose is a much
more simpler molecule it consists of two units
to six carbon chain six carbon ring okay so
we talked about how they sucrose molecule
is from and it is readily usable sugar okay.
Coming back to the slide so you have this
crypto6-phosphate so if you see the structure
of the fructose 6-phosphate now let us start
from there so photo 6 phosphate is nothing
like this suffice one chain so the oxygen
out here you have hydrogen here which is the
fifth carbon and you have the sixth carbon
out here CH 2 0 Cl3 minus this is the phosphate
group this is the sixth carbon okay and have
you hydroxyl group and this is your fourth
carbon now you are on the third carbon hydroxyl
group pointing out of the plane.
And here you have hydroxyl group and you have
another hydroxyl group attached to this carbon
which is the carbon one so this is your fructose6-phosphate
fructose 6-phosphate is using an abundant
phosphate cross locator we needed a phosphate
cross located the phosphate trans located
I am adding now, phosphate, trans locator
so this phosphate trans located is molecule
like this 
and this phosphate class locators are fairly
rich in the chloroplast okay.
This oxygen out here out here then you have
OC here sorry OCH2 H is another five member
ring out here which is H-H-H-OH and okay there
is a nitrogen CH- CH with O at the NH here
sorry this is NH and yet the top and this
is called your let me just finish this molecule
the oxygen out here hydrogen and you have
a hydrogen OH-OH-H and H-OH okay so this is
called a phosphate trans locator it is called
URIDINE this URIDINE group attached di-phosphate
glucose this is also called UDP.
So you have the di-phosphate out here di-
phosphate glucose and this URIDINE attached
to it so when this two molecules react with
each other in the presence of sucrose 6-phosphatesynthetase
sucrose 6-phosphatesynthetase is the enzyme
which is involved in it what you essentially
get out of it a is sucrose 6-phosphate sucrose
6-phosphate is nothing but this molecule this
is what you see the fructose and you have
this part which is the glucose.
So what you are we have glucose and have a
fructose which makes you the sucrose, sucrose
6 phosphate so phosphate look like this which
comes as it is if you see the structure, structure
will be like this.
Let me just draw the structure and of course
it will be left with a UDP which is the original
phosphate I am NOT drawing that again so it
will be something like this H-O and here you
have OH –CH2 so only for you guys to complete
this whole structure I wish you to complete
this part of the structure okay.
That is kind of your assignment to look at
how these things are formed so just now what
we concluded is in this whole process we landed
up with long-chain starch which consists mostly
of 1-4 glycosidic linkages and few or handful
of 16 glycosidic linkages these are long chain
apart from it we what we get is sucrose molecule
of 15 carbon ring off and one six carbon ring
of glucose and fructose they attached together
and form what we call as sucrose so these
two are the majors molecules so now coming
back to our first light of today.
So these two molecules what we talked about
is what will dictate that what is the efficiency
of this process but before we get into the
efficiency now let's take a count of how much
NADP and NADPH has been involved in this process
so coming back to the NADP and NADPH a so
if you remember we started the reaction like
this.
CO2 + H2O forming CH2O and plus oxygen this
is the first reaction what we started when
we say it carbon dioxide is getting reduced
to carbohydrates okay, where as water is getting
a split into proton electron and oxygen you
know protons, protons electrons and oxygen
now in this process we realize so if you go
back to the cycle we saw there are involvement
of ATP is out here there are two ATP's we
got involved.
And there is another ATP which got so the
first two ATP will got involved was when 3-phosphoglycerate
is converted into 13 bits phospholipid you
have two NADPH making NADP and you have another
ATP molecule converted to a DP by donating
that phosphorus group in the conversion of
glyceraldehyde 3-phosphate or three below
65 of say to Reba lows 15bisphosphate so Reba
lows 5-phosphate a single phosphate and 15
bi-phosphate is having two phosphate moieties
okay.
So if you see so in one cycle there is two
ATP plus 13 ATP right so this is one ATP to
here and one here 22 plus 13 ATP are involved
whereas you see at the NADPH there are two
NAD PA consume okay so now let us add up this
to the cycle so we talked about 3ADP + 2 NADPH
so this is what is needed to convert one co2
molecule to add one co2 molecule so for 6
you will be needing six time of this so essentially
what will happen 3ATP for one carbon so rather
141 carbon unit three ATP.
So for six carbon you will be needing three
x 6ATP so which is essentially 18 ATP molecule
will be needed similarly if this is one the
other instances NADPH ok, so for attaching
one carbon you need two NADPH so attaching
six carbon you will be needing to x 6 12 NADPH
now this is what we are going to add into
this equation what we have put forward in
the beginning to start our journey of photosynthesis.
Now we are revising the reaction you have
co2 which is a single carbon so now we make
it six now I am adding 6co2 because we need
six carbon sugar plus we have talked about
18 ATP plus you will be needing to h2o so
you will be needing 12 water molecules one
point of time plus we have talked about we
will be needing 12 NADPH okay and what you
are getting out of it is c 6 okay 6 carbon
H-12 O-6 plus it has donated 18 phosphorus
moieties.
So we are left with18ADP di-phosphate here
you have the tri-phosphate just compared okay
+ 18 phosphorus molecule which is can come
out from try to dyad I ok plus 12 in ADP plus
because it has donated these hydrogen to out
here which makes it h 12 so this is that critical
reduction process what we have been talking
all along or this reaction essentially okay
plus we talked about there will be a proton
6 H + those protons which are left.
So what we see out here if we see what is
the energy expenditure of synthesizing a X0’s
so if you go through six rounds of Calvin
cycle 
this is what you expect so this is the sum
total of the energy expenditure of a six round
of Calvin cycle when you go through it this
is what you will be obtained okay.
Now we will add 2, 3 more things before I
conclude this part.
Is what is the efficiency of photosynthesis
how it is being evaluated okay so if you have
to see the efficiency because this will be
very relevant to our next topic where we will
be talking about the c3 and the c4 plants
and how the Rubisco oxygen is activity is
be encountered in high temperature where because
of the high temperature the photo respiration
increases so the Delta G the first thing is
the Delta G zero prime for the reduction of
co2 2 hexose.
Which is a fixed carbon is plus 114 kilo calorie
per mole step one second so the reduction
of NADP to NADPH NADP+ this reduction process
is two electron process okay hence the formation
of two NADPH requires the pumping off so if
you want to NADPH molecules to be formed so
this required this part is very critical just
evaluate it carefully this requires pumping
up for photon to photo system 1.
So four photon to photo system 1 so this is
the light expenditure we are talking about
the electron given up by four system one so
it is giving out electrons in that process
if we replenished by 40 system to now for
the system to replenished those electrons
which are given out we instead of absorb equal
number of photons so automatically this also
need equal number of photon into play.
Hence sum total of photons which are needed
is if you add these two what you are getting
is it will be needing eight photon which is
the energy expenditure in terms of the photons
so what you are getting is an eight photon
are needed to generate the required NADPH
molecule okay the proton gradient generated
in producing two NADPH is more than sufficient
to drive the synthesis off so in that process
there is a proton gradient synthesis of three
ATP molecules for mark my word again the proton
gradient generated in producing two NADPH.
Is more than sufficient to drive the synthesis
of three ATP molecule and the third and the
final aspect is that.
A mole of 600 nanometer photon has an energy
content of 47.6 kilocalorie so remember this
part a mole of 600 nanometer once again 600
nanometer photon has an energy of 47.6 kilo
calorie and so the energy input of 8 moles
so the energy input of 8 moles of photon will
be equal to 3 81 kilo calorie why 8 moles,
from where this eight mole is coming?
So she will little further up see the four
photon and for photon eight.
So this is from where this eight moles of
photonics 381 kilo calorie this brings us
to the concluding part of this lecture thus
the overall efficiency of for synthesis and
the standard condition is 381 which is approximately
thirteen percent so from where 114 is coming
114 is coming with vh1 you know from where
it is come one is coming from here and 114
is coming from here.
The Delta G of conversion so when you divide
114 by 381 x 100 so efficiency of photosynthesis
on the floor of Earth is thirty percent so
this is how the whole energy dynamics so if
you look at look in the first slide what I
showed you in the beginning of the class to
start off with.
So this is we talked about their formation
of the starch and the sucrose right followed
by we talked about that ATP and NADPH and
the whole expenses of course barring a site
we did not talk about this one we did not
talk about this one we did not talk about
this one we did not occur this one what we
talked about is the water sunlight which is
involved in the form of photons and the energy
needed to convert this reaction co 2 to 6
carbon and what we are getting out here is
let me come back okay.
So the take-home message for you triple is
this part a mole of this much amount of light
which is 380 kilocalorie which is 381 kilo
calorie what is needed to convert one hexose
molecule which is 114 and it is that what
you are getting is we are talking about thirty
percent efficiency so overall photosynthesis
is thirty percent efficient now from here
keeping this in mind and talk keeping in mind
the problems Rubisco faces it has oxygenates
as well as carboxylates activity and there
is always a tug-of-war there is a very interesting
thing as a temperature increases specially
added semi-arid tropics of the world where
the temperature is really high.
In those places the oxygen binding capacity
of Rubisco increases in other words photorespiration
increases your consuming oxygen how the plan
get around it because this is very important
because if you remember the very first lectures
what I was giving you I told you that if we
have to get our huge bio mass we have to ensure
it is not the cost of environment because
if the system itself is consuming a lot of
oxygen it is not going to help us so what
nature has developed this will take us to
one of the very unknown study made by one
Russian followed by an Australian scientist
hatch and slack.
And how they discovered something called c4
plants from here we'll move on to something
now you know the efficiency overall officials
which is thirty percent we have talked about
that drawbacks of Rubisco and we have also
talked about why lot of mutagenesis of studies
of you know manipulating the Rubisco molecule
as of now it is not really successful because
Rubisco is a peculiar enzyme sitting out there
so what nature has devised to ensure that
the Rubisco efficiency is maintained at high
temperature where otherwise Rubisco will behave
more for further expression then for utilizing
the carbon dioxide.
So we will close in here will resume our next
class where we will talk about c3and c4 plants
and that will kind of bring us to the point
the how these bio first set of bio cells are
formed by nature from there we will take up
how the conversion is going to take place
and what are the basic paradigm how these
starch sugars cellulose bunch of glycans and
everything which are formed how to convert
them and how much energy has to be consumed
to convert them as of now we have talked about
how much energy is needed to make them by
nature itself next ways we will talk about
once we are done with the c3 c4.
We will talk about how much energy man has
to put to convert this too much more usable
skills so this is how the whole bio energy
landscape will run through what we have a
fairly good idea or a grip on the system about
what is happening in nature and the form of
photosynthesis photorespiration group disco
light reaction dark reaction formation of
starch and sugar molecules and from there
we will move up how we can convert them once
we harvest all that okay thank you.
