today we will
start
2:24 this is the last job
of the book and it will be the last
chapter for our course also the name of
the chapter is the chemistry of life
organic and biological chemistry now we
will probably go fast in the first part
organic chemistry part I assume that you
know those from the high school but at
least you will have a chance to learn
the English aspect of the organic
chemistry those that come from the high
school that the instruction was not
English actually it's at least oh it's
very interesting actual life chemistry
is very very interesting as I as myself
as I read it I'm not a biochemist I'm
not an organic chemist I'm an inorganic
chemist actually but I found it very
interesting also myself very very
interested as a matter of fact when you
start thinking about it how would the
life is simply based on chemistry you
know chemical interactions chemical
reactions molecules that's all it is but
that's where the life is going on how it
goes sometimes hard to answer now let's
continue as I said I would go fast in
the first part organic part now organic
actually says we will focus on molecules
that bridge chemistry and biology
actually the biologies chemistry with
nothing else just a special part of
chemistry in a matter of fact and most
common elements in this organic
chemistry and biochemistry are carbon
hydrogen oxygen and nitrogen
say now the organic chemistry
study of compounds containing carbon so
those are called organic compounds but
again we know that not only carbon we
will have hydrogen oxygen nitrogen those
organic compounds biochemistry is the
study of the chemistry of living systems
living systems so let's go through the
first part quickly the organic chemistry
now general characteristics of organic
molecules carbon makes four bonds we
know that actually we learn in all
single bonds tetrahedral sp3 hybridized
so if carbon simply makes four single
bonds then the hybridization on carbon
will be sp3 hybrids and one double bond
if you have carbon makes a one double
bond then the hybridization becomes sp2
types and the structure around that
carbon is trigonal planar one triple
bond that means we have an SP
hybridization on that carbon and say
linear and carbon hydrogen's are most
common carbon hydrogen bonds in organic
compounds and again carbon forms stable
bonds with many elements including
carbon hydrogen oxygen nitrogen and the
halogens in organic compounds also we
will see not the hellige ins but these
are very common in organic molecules now
a group of atoms that determine how an
organic molecule reacts are called
functional groups so again you see the
functional groups in organic chemistry
is very important as it says it
determines how the organic molecule will
behave chemically as a matter of fact so
those functional groups are important
now if we think about the solubility of
organic compounds again most prevalent
bonds are carbon carbon and carbon
hydrogen which
nonpolar we know that and the solubility
in water is low for many organic
compounds remember water will dissolve
either ionic compounds or polar
compounds or compounds that can form
hydrogen bonds as a matter of thang and
those most organic compounds we don't
have those now organic molecules such as
glucose that have polar groups are
soluble in polar solvents remember in
the exam this was why the glucose was
soluble in water about not hexane
cyclohexane I guess again the glucose
has the hydrogen bonding capabilities
and glucose is also polar and it
dissolves in water molecules with long
non polar regions and polar regions act
as surfactants bridging simply bring in
polar material into a cue solution using
detergent and soaps actually if you have
molecules one side is polar the other
side is nonpolar and it's a big molecule
what really happens that when you throw
in these molecules into the water the
water the the polar part of the
molecules points to the water interacts
with the water but the nonpolar part
interacts with each other and these are
simply called surfactants as a matter of
fact and they try to nonpolar part try
to weight from the water and the polar
part is directly interacting with the
water as a matter of fact now our
acid-base properties again many organic
molecules contain acidic or basic
functional groups carboxylic acid this
is the main group that gives the acidic
character to the organic compounds are
the most Commons remember this oxygen is
double bonded to the carbon and this Oh
H is single bonded to the carbon and
that hydrogen is the acidic hydrogen
means that it will dissociate and to
give H+ proton in solutions now amines
NH 2 NH r or NR 2 groups they also by
bind to the carbon they behave as the
basic part of the organic molecules why
because they have this lone pair
electron on the nitrogen and that lone
pair electrons on the nitrogen behaves
as a loose base and gives the basic
properties basic properties now are the
organic compounds are also classified as
like hydrocarbons now hydrocarbons again
it says consists of only carbon and
hydrogen so an organic compound is made
of only carbon and hydrogen
we call it hydrocarbons they are grouped
based on the number of bonds between
carbon atoms there are four basic types
of hydrocarbons alkanes alkenes alkynes
and aromatic hydrocarbons now again we
know all if simply there is no double
bond in an organic molecule hydrocarbon
actually it is alkanes if there is one
double bond at least it is called
alkenes and if it has at least one
triple bond between two carbon atoms it
is called alkynes again and the aromatic
hydrocarbons is the cycle one's actually
now let's see here are some examples
this is the like alkane an example
single bond and a double bond and triple
bond and aromatic hydrocarbons each of
those just gives an example now
properties common to hydrocarbons if you
go through these since they are nonpolar
they are insoluble in water but soluble
in nonpolar solvents again hydrocarbons
are soluble in nonpolar solvents only
now the mountain points and the boiling
points are determined by dispersion
forces remember again boiling point and
melting points are determined by
intermolecular forces and since these
are all nonpolar molecules actually
hydrocarbons and the main
force that operates in these compounds
is the dispersion London dispersion
forces again now remember again when we
have large molecules this dispersion
force it becomes very strong and the
mountain points and the boiling points
becomes pretty high as a matter of fact
now here again it says low molar mass
hydrocarbons are gases moderate molar
mass hydrocarbons are liquids high molar
mass hydrocarbons are solids again
you remember gain dispersion force are
the only intermolecular forces that
operates in these compounds and here
some examples of those hydrocarbons are
given up to the carbon number is what
here is about 10 decane and you see
again gives the boiling point and its
charge from minus 161 for methane and
goes up to one hundred and seventy four
plus hundred and seventy for melting
points in fact a boiling points actually
of these compounds very different and
it's simply based on the mass of the
molecule the higher the mass the
stronger and intermolecular forces and
higher the boiling point now uses of
some simple alkanes again just examples
methane is the simplest one and in
natural gas we use that and most of
natural gases methane
now propane is again 3 carbon
hydrocarbon and in bottled gas heating
and cooking fuels actually those tubes
gas tubes contains the propane that we
buy now the butane is also used a
similar way in disposable lighters and
fuel canisters for camping for example
we use those all of them are gases now
alkanes with carbon 5 to 12 are gasoline
that's what we use in automobiles
actually they are gasoline's
now the formula I'm not going to go
through this I guess these are simple we
can write those formulas of the compound
open
structural formula this is called this
is sort of close formula again and we
know how to write them like this all of
these are the same structure of alkanes
again carbon in alkanes are sp3
hybridized remember there is no double
bond in alkane and tetrahedral we know
that the angle is 109.5 in straight
chain form all carbons connect in a
continuous chain like you know one
carbon is bonded to the other carbon and
carbon can make four bonds so it is
possible for a carbon atom to bond to
three or four other carbon atoms making
a branch alkane so we can have a chain
structure or branch structure for
alkanes compounds with the same
molecular formula but different
connections of atoms are called
structural isomers as seen in the next
slide again here we have the structural
isomers of butane two structural isomers
these are the open the formula of those
this is the molecule in fact and this is
the pentane we have three structural
isomers of pentane now again what you
see here the mountain permanent point
and boiling point of these isomers are
quite different again right in between
the structural isomers even though the
clothes formula is the same but the
structures are different why they are
different because intermolecular forces
the strength of the intermolecular
forces changes from one isomer to the
other isomers again now naming I will
not simply go to this how to name the
compound you can read those as a matter
of fact like that
now cyclo alkanes the cyclic ones again
here these are the some examples that
formed rings or cycles all saturated no
double bonds again if there is no double
bond in a hydrocarbon we call that
saturated if there is one at least
double bonds we call that unsaturated
hydrocarbons again now possible with at
least
three carbon atoms but sp3 hybridization
requires so stable molecules for carbon
ring is also not very stable five carbon
and more have room for proper bond angle
now cyclo and as prefix or alkane name
we use that Amman cyclopentane
cyclohexane for example this is cyclo
hexane this is cyclopentane now this is
cyclo propane but again as the number of
carbon atoms in the cycle decreases it
becomes more unstable because there is a
strain particularly this cycle propane
is not very stable there is quite a bit
strain on these but larger cyclo alkanes
are more stable now reactions let's go
very quickly with these of alkanes
alkanes are relatively unreactive due to
the lack of polarity and presence of
only carbon carbon and carbon hydrogen
bonds which are very stable so when you
have a stable strong bond actually and
plus there the molecule is not polar
molecule the reactivity is pretty low as
in this case and they do not react with
acids bases or oxidizing agents as a
matter of fact however the most
important reaction observed in is
combustion again these alkanes are the
source of energy for a lot of factories
and places again and here if we have the
methane molecule and alkane in fact and
it reacts with the oxygen and gives
carbon dioxide and water this is the
only product actually if you have enough
oxygen in this full combustion and this
reaction is called combustion reaction
and these are again very exothermic
reactions for this case for example -
two thousand eight hundred and
eighty-five kilojoules per two moles of
this that's a very very high as a matter
of fact and so these combustion
reactions becomes a very good source of
energy
now saturated versus unsaturated
remember if you have hydrocarbons with a
single bonds only are called saturated
haruka hydrocarbons these are simply the
alkanes now if you have alkenes and
alkynes and aromatic hydrocarbons have
fewer hydrogen atoms than the alkanes
with the same number of carbon atoms
they are called unsaturated actually the
measure here is if they have at least
one double bond or triple bond that
becomes an unsaturated hydrocarbon
unsaturated hydrocarbons are more
reactive than saturated hydrocarbons
this is important 9 yes we should always
remember that the double bond is sort of
the starting point of the reaction of
these hydrocarbons therefore they are
more reactive in fact unsaturated carbon
hydrocarbons now alkenes double bonds
actually the one which have a double
bond contains at least one carbon-carbon
double bond no free rotations about the
double bond remember again this is a PI
bond and a sigma bond no free rotations
and if you have here four other hydrogen
atoms attached to this or other groups
it is a planar longest chain that this
is the name but this is a planar
molecule again for example when we have
ethane molecule and it's a planar
molecule all of the hydrogen's and the
carbon are on the same plane now these
are the geometric isomers as we said
again let's see since there is no free
rotation around a double bond the
directions of the longest chain can
differ for four or more carbon atoms now
compounds that have all atoms connected
to the same atoms but differ in
three-dimensional arrangement are
geometric isomers now alkenes have cysts
and trans isomers as we see over here
for example this is an organic compound
containing
double bond so this is an alkene now
this again considering this hydrogen and
the carbon here and that carbon and that
hydrogen and these two carbons are all
on the same plane
it's a planar molecule so if they are in
the same plane then the place of the
hydrogen would respect two methyl groups
actually can be like this or it could be
actively let's say again it could be
like like this or it could be in fact
like this now these are simply called
the cysts we have the two hydrogen on
the same side and this is called the
trench the two hydrogen's are in
opposite side again considering all of
those are planar again this trans and
since isomerism is simply originated
from the plane arity of the molecule if
the molecule is not planar we will not
have since and trans isomers now all
kinds of triple bond
unsaturated and we just named that again
acetylene is the simplest all kinds
actually addition reactions of all keys
and all kinds again these are
characteristic reactions add atoms to
the double or triple bond making it
saturated or mass more saturated and pi
bonds are broken and the electrons from
Sigma bonds to added atoms work with h2
for example or HX in fact or sometimes
water or x2 can be added for example
when we have x2 is bromine molecule
added to the double bond this is a very
characteristic reactions of the bromine
with our alkenes actually and we add the
two bromine to two carbons over here and
this is a saturated now right
this is unsaturated that's a saturated
and again with the hydrogen we can add
two hydrogen's over here one mole for
one more
and gives you a saturated hydrocarbons
or we can have simply add water in the
presence of sulfurous acid h2so4 and we
get an alcohol or we can add simply
chlorine to the triple bond and get like
this and this will also have cysts and
trans isomers too right so this is a
trans isomer as you see because when we
have a double bond it's a planar
molecule and since ni simmers trans
isomers are possible again now aromatic
hydrocarbons is the aromatic
hydrocarbons have six membered rings
containing localized and delocalized
electrons the PI ring is much more
stable than PI bond so aromatic
hydrocarbons are much less reactive than
alkenes and alkynes they undergo
substitution reactions rather than
addition reactions groups replaces
hydrogen on a ring for example nitration
halogenation and alkylations
here are the examples again this is
benzene is the aromatic ring actually
mainly and we simply make addition to
benzene and we get nitro benzene like
this or we can add bromine and we get
bromo benzene you see again these are
replacement of the hydrogen on the ring
by the entering group here and we can
also add two benzene this chloro ethyl
methane or ethane to get the ethyl
benzene like this these are simply the
automatic hydrocarbons and their
reaction types now this is gate again
the nomenclature I will just go through
this you can read it here is the
probably benzene this is the naphthalene
and this is anthracene toluene and
pyrene these are it would be good
general culture of chemistry knowledge
actually if you know those as a matter
of fact now the functional groups
remember are very very important
in organic chemistry because the
chemists chemical property of the
organic molecule is determined by the
functional groups
what are these functional groups again
we see here the functional groups we see
again the chemistry of an organic
molecules is largely determined by the
functional groups
it contains the that it contains it says
R represents the alkyl portion that's
the carbon and hydrogen part of the
organic molecule now here are we simply
the functional groups a double bond is a
functional group and triple bond is the
another functional group and we have the
Oh H let's go threes alcohols for
example the O H is a functional group
alcohols contain one or more hydroxide
group actually and it is simply called
if you have more than one o age group
it's called poly hydroxy alcohol
actually they are named from the parent
hydrocarbon and the suffix is changed to
o L and a number designates the carbon
to which the O H group is attached
actually there's a like to propanol
means that the Oh H is added to the
second carbon here
number two carbons and two methyl groups
and these are again the alcohols now our
properties are and uses of alcohols
they're all polar molecules remember
they have an O H group and they are
polar and lead to water solubility and
higher boiling points it dissolves they
all dissolve in water methanol for
example used as a fuel additive ethanol
in alcoholic beverages that we drink
actually
now ethylene glycol is used as an
antifreeze and a glycerol is used for
cosmetics skin softener and food
moisturizers phenol making plastics and
dyes and topical anesthetic in throat
sprays and cholesterol and import
by a molecule in membranes but can
precipitate and form gel stones or block
the blood vessels this is again what the
high cholesterol in the body causes
remember blocks the veins again now
another functional group is ethers again
now the ether have RoR that means one
oxygen bonded to two alkyl group here
again formed by the dehydration between
alcohol molecules when they dehydrate
the alcohol molecules not very reactive
except in combustion it says and used as
solvents for organic reactions and like
we have over here diethyl ether this is
simply called diethyl ether if you have
one methyl group dimethyl group it's an
acetone we know we use that and
tetrahydrofuran all of these are again
liquids and use as solvents now how
about the solubility of ether in water
would you expect as good as the alcohol
solubility of ether no actually but
there's going to be hydrogen bonding
between the ether molecule and the water
molecule right the hydrogen off the
water molecule can simply interact with
the lone pair electron on the oxygen in
ether but again the solubility of ether
is water is not very good as a matter of
fact now another functional group is
carbonyl group in fact and this carbonyl
group is carbon double bond right here
and functional groups containing carbon
double bonds also classified as
aldehydes ketones carboxylic acid esters
and amides let's look at those in
examples this is actually the
formaldehyde right aldehyde actually if
you have only a hydrogen bonded to the
carbon which is bonded to an oxygen it
is called aldehyde like this this is an
aldehyde
this is also another aldehyde I said all
the height or ethanol now in ketones we
have two R groups attached to the
carbonyl carbon atoms like this and this
is the acetone dimethyl ketone actually
it's called propanone another different
name and this is another ketone you see
again if the carbon atom which is bonded
to the oxygen is bunts to two other
carbons like this it is the ketone now
important all the Heinz and ketones that
quickly let's go through this many
aldehydes are natural flavorings
so those aldehydes for example vanilla
and cinnamon and spearmint and caraway
are from aldehydes and ketones are used
extensively as solvents the most
important saw one other than water is
acetone and that's for two actually
three carbon ketone remember and which
dissolves in water and dissolves many
organic compounds and it simply
dissolves in water to acetones better
than ether actually now carboxylic acids
as we have here the structure you have
the hydroxyl group bonded to the
carbonyl group that means the carbon
which binds the oxygen with a double
bond like this and these are the
different simply acids and we may have
like two carboxylic group again in one
acid in one molecule too so let's say
hydrogen on the hydroxyl group is weakly
acidic that's what the makes the
compound acidic that hydrogen bonded to
the oxygen which is bonded to the
carbonyl carbon atom is acidic and it is
ionisers to give h+ again important in
manufacturing polymers for films fibers
and pains actually oxidation products of
alcohols
are actually carboxylic acids that means
if you simply take the ketone and then
oxidize it you get the alcohol and you
take the alcohol and oxidize it one more
step then you get the acid remember
those are inorganic chemistry
now esters is the combination of an
alcohol and an acid carboxylic acid and
it again gives what gives off a
condensation reaction sort of gives off
a water
he says the products of reactions
between carboxylic acids and alcohols
they are found on many fruits and
perfumes and naming is a gain name the
alcohol part as an alkyl name separate
words is the acid part as at 8ni now
this is simply ethyl butyrate and the
acid here is beauty Cassatt right with
four carbon atoms they if you have an O
H here it said B trick acid now this is
the ethyl alcohol and when you simply
combine them and take a condensation
sort of take one water out you get the
ester and the name of this is ethyl
butyrate no that's just the composition
of esters again heating an ester in the
presence of an acid catalyzed and water
can decompose the ester this is called
hydrolysis reactions of ester if you
simply hydrolyze the ester you get the
acid and the alcohol again just like the
starting materials heat in an ester in
the presence of base results in spawn if
occations
making soap this is an acid we get the
original compound here we get a soap
like this that's called the spawn if
occation reaction actually remember now
nitrogen containing organic compounds
these are called amines and amines are
organic derivatives of ammonia nh3 one
two or all three hydrogen atoms can be
replaced for our groups again in the
amine
this is simply the vanilla mean like
this or we can simply replace the
hydrogen on the nitrogen
what with another group again if
hydrogen in nh3 or an amine is replaced
by a carbonyl group and directly
attached to Co double bond oxygen and
amide is formed right this is how the mi
is formed this is the acid acetic acid
and this is the dimethyl amine like this
and this hydrogen and that Oh H forms a
water molecules and we get simply a
might over here mi group like this
okay now this this is our thinking
important high relative what is a
chirality now carbons with four
different groups attached to them are
chiral
now these are optical isomers or
enantiomers these are simply called
optical isomers and enantiomers now
enantiomers have the same physical and
chemical properties when they react with
non chiral reagents and aunt enantiomers
rotate plane polarized light in opposite
directions let's simply look at this one
more time now suppose that we have this
compound and let's say we have a ch3
group here now what does this means this
simply means that four groups bonded to
the carbon the same carbon are different
now remember this is tetrahedral
structure like this and the angles are
109 degrees now if I simply take a
mirror put a mirror here sort of a two
side
mirror you can call a one-sided mirror
and the mirror image of this molecule
would simply be like this Corinne over
here and then bromine here and then we
have the iodine on this side and the ch3
group over here like this now if you
make this molecule and this molecule
again try to put them on one on the
other side you know superimpose one to
the others you will never be able to do
that never be able to do that so it is
just similar to two hands if you take
this and take a mirror here the mirror
image of this one would be this right
now when you take these two hands here
try to superimpose them there will be no
way you can simply put superimpose those
right so if a molecule has this property
that means that if the mirror image of a
molecule is not superimposable on itself
to itself that molecules is called
optically active molecule right
optically active molecule now or it is
called chiral molecule it is chiral
so simply optically active or it is
called chiral this is another word that
we use for the same things now these two
molecules chemically are very similar if
they are reactant with non chiral
molecules non kind of molecules but if
they are reacting with another chiral
molecules the reaction of the this one
and that one will be different will be
different now what does this means
actually this simply means that if you
have only this compound in a solution I
have a solution here
like this and in this solution that I
have only one of this compound these are
simply called enantiomers the mirror
image of these are simply called
enantiomers yeah if you have one
enantiomers put here and then you send
here plane polarized light plane
polarized light now what is plane
polarized light that's another things
plane polarized light simply means that
the elec
remember the electromagnetic radiation
light has both the electrical and
magnetic properties and there's
oscillating electrical field vector and
also oscillate in magnetic field vector
in that now this plane polarized light
has the electrical field vector
oscillating only on one plane like this
or like this same things actually on one
plane right it's called plane polarized
now how you get the plane polarized
light you can get two plane polarized
light by combining two circularly
polarized light hmm so the circular
polarized light would be again as follow
let's say that we have simply a
circularly polarized light simply
circulating like this that means this is
left circularly polarized left let's say
this this would be all right
right circle polarized okay this is
let's call that right circularly
polarized light and that simply means
that if you simply take the electrical
field vector like this as the light
simply goes in this directions it simply
goes like this the electrical field
vector rotates like that right sort of
make a circular motion circular motion
and this is called right circularly
polarized light now you can also have
left circle the polarized light
like this and this left circularly
polarised light would simply go in this
direction right this goes in that
direction again this is the electrical
field vector that's you can think about
that and as the left circularly
polarized light goes in it goes in the
other this direction electrical field
vector makes this kind of motions again
circular motions like this now when you
combine these two on the same phase at
the same time what will really happen
let's think about that that simply means
that if you get them all in the same
things on superimpose this left and
right circularly polarized light so the
electrical field vector of one will
simply go in this direction and the
other one will go in that directions now
at this position right here the
electrical field vector will be added up
right now as they move in this direction
like this right and the sum of the
vectors will get smaller smaller smaller
that means that sum of the two vectors
left and right circularly polarized
light electric field vector we get
smaller and smaller here it would be
what it would be actually not will be
smaller that simply means they will
cancel out as a matter of fact right
because if you take the this vector and
make the vectorial sum that would be
zero here it will be zero and here it
will be also maximum - so what does that
means if you have a left and right
circularly polarized light combined in
the same phase that means that the
electrical field vector for example only
oscillate in this plane right here and
this is called left this is called the
plane polarized light plane polarized
light now if I take that plane polarized
light actually the combinations of these
two
through this solution which contains
only one enantiomers right now since
this vector here that means left
circularly polarized light will go in
that directions and the other one will
go in the other directions and this
molecule looking from this side and from
that side will be different that means
that as they go through the solution
which contains optically active
molecules left and right circularly
polarized light interaction with this
molecule will be different right so as a
result of that what really happens the
speed of these two in this solution will
be different than refractive indexes
will be different the speed then will be
different that means when they come up
for example rotate like this come in
this position this will be a little bit
simple I will be rotated like that right
so that means if you have a solution
that contains optically active molecule
and send a polarized light let's say in
this directions like this when it comes
out from the solution it will be rotated
just a little bit like that right why
due to the interactions of left and
right circularly polarized light with
optically active molecule are different
right that's different that's that's the
reason now then for example if one of
the enantiomer rotates this plane
polarized light in this direction let's
say ten degrees now if I put the other
enantiomers in another solution passed
then it will rotate just the opposite
directions but the same angle right now
if I have the mixture of those in
solution what will happen
no rotations right there will be no
locations because left and right will be
the same so that's why what the
optically active compound means and
that's what we call the enantiomers
again here
so this this is again this is what I try
to explain you enantiomers rotate plane
polarized light in opposite directions
that means if I have one enantiomers in
one solution rotates in this direction a
little bit when the light passes through
that and the other one if I have that's
called the on the other side but if I
have the mixture of those equal amounts
50/50 there will be no rotations no
activity actually there will be no
optical activity as a matter of fact so
then they're not this is not only
specific to the organic molecules
actually any molecule which have a
mirror image that is not superimposable
that will be optically active that will
be optically active very different
property actually now here is again
chirality and pharmaceuticals this is
this is really important because as he
says here many drugs are chiral
compounds chiral compounds means they
have enantiomers means they're mirror
images are not superimposable and again
here it says equal mixtures of
enantiomers is called racemic mixture
that means that they loses their optical
property right optical activity because
if you have 50:50 mix the enantiomers
there will be no optical activity and
plane polarized pass through that
solution will not be rotated either to
the left or to the right with certain
angles now often this is really
important often only one enantiomer is
clinically active the other can be inert
or harmful you see the same molecule
just the mirror image of the same
molecule one enantiomer is used as a
drug it cures the disease and the
another entry emerges sometimes do not
cure to disease but sometimes it's
harmful so what does that mean that
means when we prepare this drug we have
to separate those two enantiomers from
as a matter of fact and sometimes it's
not easy to do that you know to to
separate the enantiomers because usually
we get the mixture of the enantiomers
rate which we call that racemic mixture
of the enantiomers now here again you
see now this carbon for example is an
optically active carbon center why
because the groups bonded to that four
groups are different here like there
should be another hydrogen here actually
one this group over here that group
there OAH and the hydrogen's will be
optically active here yeah I guess this
is the open form of that you see again
that carbon there has four different
groups bonded to that one two three four
and this is the criteria how we decide
whether a compound will be optically
active or it will not be optically
active it will be chiral in other words
or non chiral right it should had at
least one carbon atom which four groups
bonded to that carbon atom should be
different from one another Ryan should
be a different one from one another
okay now ah the second part of this
chapter is biomolecules and biological
chemistry this is really very
interesting as I said we will see that
now biomolecules are biopolymers they
are large biological molecules and they
are built from small molecules small
molecules now we can
when we say biochemistry actually
biochemistry simply means the chemistry
of living organisms right chemistry of
living organisms but when we say
chemistry that means there are molecules
there right reactions between the
molecules and so on
now biopolymers again here are very very
large molecules how large hmm they go up
to from fifty thousand to six million
atomic mass units that means very very
large big molecules and most of them are
polymers they are most of them are
polymers and what are these they're
proteins for example the classifications
of these biopolymers proteins
polysaccharides or carbohydrates nucleic
acids these are the polymers and we also
have lipids but the lipids are large
molecules but they are not polymers we
will see those again now and other
things here is to build this large
molecules which are polymers or bio bio
polymers we need energy right first of
all because the synthesis the formation
of these big molecules from small
molecules that is readily available for
us in the biosphere
you know like carbon dioxide waters and
other things like that requires energy
to simply build up these large molecules
now second things is if you look at from
the entropy standpoint the living
organisms which have these large
molecules are more organized systems
right what does that means that means
that the big molecules is more organized
too
that simply means that in the formations
of this polymer big molecules the
entropy change will always be negative
or positive
we'll be positive right because there
will be higher order that means that the
entropy change will be positive no
negative the entropy change will be
negative compare again if you take a big
molecule and obtain that from smaller
molecules in a chemical reaction the
entropy change for that will be negative
again right now but what does that means
that simply means it gains the second
law of thermodynamic that means for
spontaneous processes we expect that the
entropy change is positive that means
the entropy change increases so there
are two aspects of this synthesis of
these biopolymers big molecules from the
small molecules now where we get the
energy now animals have no potential of
using directly the solar energy actually
the most of the energy we get from from
the Sun on the earth right so how we can
utilize how the animals or human beings
that are also animals can utilize the
solar energy by the help of the plants
right the plants actually plant take the
solar energy and they convert it to
carbon dioxide and water converted to
sugar or other molecules and this is
called photo synthesis right
photosynthesis and as a result of this
photosynthesis in the plants actually
green plants we have some fruits or
other foods that produced by these
plants and which contains sugar or other
molecules that can give us the energy
that we need for these reactions so you
see again the animals uses the plant
photosynthesis to get their energy needs
to continue their life actually right to
continue their life so that's in other
things that we
to think about that as a matter of fact
okay now let's continue the proteins are
polymers and the monomer of proteins are
amino acids actually we stop here