Oligosaccharides, Polysaccharides Introduction Video Lecture - NEET

hello friends this video on biomolecules
part 6 is brought to you by exam few
calm no more fear from exam ok so with
this I think we can now go ahead with
oligosaccharides I gave you a brief
discussion on monosaccharides they are
the simplest sugar now the next is all
egos occurrence so these are
carbohydrates that yield two to ten
monosaccharide units on hydrolysis so
they can be hydrolyzed further and they
can give two to ten monosaccharides unit
that is why the as I said the term oligo
means few so that few refers to two to
ten here in this case now carbohydrates
that I yield to monosaccharide units
therefore disaccharides carbohydrates
which yelled three monosaccharide units
are called trisaccharides
for tetra and that means so they are
further classified as disaccharides
Diegans to try these three tetra is four
and so on depending upon the number of
monosaccharides they provide on
hydrolysis now you understand what is
hydrolysis you add water and cut down
the oligosaccharide most common of these
oligosaccharides and disaccharides so we
will talk specifically about
disaccharides and we will also take from
very very common examples of
disaccharides which we often use in our
day to day life so some of the common
examples of disaccharides we will see
very soon
so here lactose is a disaccharide
lactose is the sugar which is present in
milk it is found in milk now if you
hydrolyze lactose hydrolyze means you
will add water so this is the process of
hydrolysis so which bond will be broken
this is one sugar unit this is another
so if you see here this is your COC bond
that is the glycosidic bond now when you
add water if this gets broken into oh-h
here
and Oh H sure so you get one galactose
and one glucose now one is another
important thing to note here is that it
is not always necessary that on
hydrolysis both the units or both the
monosaccharides which are formed has to
be the same they can be same they can be
different so it depends on the
composition of the disaccharide so a
disaccharide can be made up of two same
monosaccharides or it can be made up of
two different monosaccharides so here in
this case they are two different this is
galactose and this is glucose both of
them are monosaccharides and what is lac
this lattice is the enzyme in presence
of which this reaction take place so we
are clear with whatever we have
discussed so far now let us move on to
polysaccharides polysaccharides which on
hydrolysis will yield a large number of
molar saccharides unit that is it will
give more than ten monosaccharide units
so they are called polysaccharides
examples would be starch cellulose black
poking gums these are some of the
examples of polysaccharides I think some
of these are quite familiar to you magic
of cellulose where have you heard the
name cellulose before exactly why we
were talking about the plant cells we
talked about the cell wall which is
exclusively present in plant cells and
the cell wall is made up of cellulose so
this is the same cellulose it is a
polysaccharide talking of starch where
have you heard the name starch food is
stored in the plant in the form of
starch so these are the things where we
have heard all these terms but we never
knew what they are exactly so starch is
again a polysaccharide now here on the
screen if you look at the structures of
starch Anne's then you lose what you see
you can actually make out the
monosaccharide units this is one who
knows
right this is neither monosaccharide
this is another monosaccharide and so on
and they are all bounded by this
glycosidic bond so this is the
glycosidic bond so in this case what
happens here also the process of
hydrolysis take place if you want to
break it down but here the process will
need to amend you have to repeat the
hydrolysis like there I was telling you
like if you give one molecule of water
this one bond will get broken now when
you have so many bonds like this so
definitely you need some enzymes to make
the reaction faster you might come out
with water and the environmental
reaction conditions that might vary but
the process will still remain the same
so here also hydrolysis will break
starch into all the constituent
monosaccharides similar in case of
cellulose also you can see the same
thing so if you look at starch and
cellulose if you look at their formula
that reads the same but it is just back
the way they are arranged is different
so their structural arrangement is
different and because of which there is
a lot of difference between their
properties so when you think of a
cellulose what comes to your mind
anything like grass anything like plants
they have a lot of cellulose when it
comes to starch what comes to your mind
something like bread which has starch
now glue see is lot of similarities
between a bread and a grass no right
because the property is are extremely
different just because of their
different arrangements of the carbon
hydrogen and oxygen so this is about the
polysaccharides so now another important
thing which I would like to mention here
is when you talk about monosaccharides
that is glucose fructose arrows so these
monosaccharides are basically used as
instant source of energy for example you
are feeling too weak or you have done a
lot of exercise on you are suddenly
married
what do you do you drink a glass of
glucose and you get some energy so these
kind of and I'm not talking about
glucose and that sense that it is a
carbohydrate I am trying to say use
monosaccharides which are there in your
body whether it is glucose or
destructors they give you instant energy
if you need some energy immediately that
is provided but they do not act as
energy storage but polysaccharides act
as energy storage so they can store
energy for later use for example now why
is that
that is because glucose cannot be
further hydrolyzed so glucose is already
there in its simplest form so it can be
utilized immediately so that is an
instant source of energy but when it
comes to the polysaccharides for example
starch or like glycogen you just cannot
utilize them as it is because if you
want to utilize them first they need to
be hydrolyzed and broken down into
monosaccharides and only then they can
be utilized so polysaccharides are
basically used as storehouse of energy
and attached by starch is prominently
the storehouse of energy in plants so
starch is used for energy storage in
plants and glycogen is used for energy
storage and animals so because of their
structures you can understand why
polysaccharides are used as energy to
house of energy whereas monosaccharides
are used as instant sources of energy so
this was a brief introduction to all the
three types of carbohydrates
monosaccharides oligosaccharides and
polysaccharides now we will spend some
time to understand some examples of each
of these types
now here comes another important thing
polysaccharides are not sweet in taste
hence they are also called as non sugars
now say therefore I was telling you
right even though most of the
carbohydrates are sweet in taste but
there are some which are not but still
they have saccharides in their name so
polysaccharides are dual so they are not
at all sweet in taste that is why they
are also known as non sugars thank you
please visit www.payoor.com to watch
more videos attempt free online test
get free study material find tutors and
mentors thank you once again