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Hello students today we are studying
chapter Ching its nature expression and
regulation in that we are studying topic
Lac Operon
when I say Lac Operon it means lactose
operon present in e.coli let's study
about this today.
Lac Operon when i say  Lac Operon it
means
lactose operon that is present in Ecoli
I know what is this lactose lactose is a
form of sugar we all are aware of
glucose sucrose now lactose is also a
form of sugar and it is used as a food
source by a ecoli what do we mean by
when I say operon now i say operon
I can send simple language isn't
mechanism so what is this Lac Operon
whenever ecoli uses lactose on
lactose is present in the media of
e.coli that time lactose operon is
working so whether lactose has to be
used or lactose requirement is not
present is decided by this open or lack
of it how does that function inside a
colon the lactose operon mechanism
basically have an operator gene a
promoter gene and Lance said Lac X and
likewise gene now what is this promoter
sure we all know that if there is
lactose present in the media in which
Ricola is residing that lactose has to
be converted into simple sugars which is
glucose so that equalised should use it
and to convert it into simple sugars
there has to be certain enzymes that has
to be produced now this enzymes will
only be produced if RNA polymerase comes
and binds to the promoter region
remember the process of transcription in
transcription mRNA or promoter region
will have the information and then once
RNA polymerase comes and binds to the
promoter region that protein or you can
said that enzyme will be synthesized
which will break down lactose so
students in case if the media is not
having lactose or the e.coli dozen as
the requirement for lactose don't don't
think so that this finding of RNA
polymerase to the promoter and then
forming that enzyme would be waste of
energy or waste of ATP obviously in such
cases what happens is to the repressor
region or you can say to the operator
segment a repressor protein comes and
bind and this repressor proteins
The Binding of RNA polymerase to to the
promoter region there were three genes
which are involved in this segment and
the enzymes are beta galactosidase and
lactose permease
black opium when I talk about slack open
on what I'm trying to speak about is
lactose operon that is present in e.coli
or the machinery that's present in
Equalists so that it could use its sugar
lactose as a food source
now lactose operon or against a lac
operon is an example of inducible
control when I say inducible control it
means a control with or a Canseco
machinery which can be on and off
basically switch on and switch on is
possible you can switch on it whenever
required and switch off it whenever
required now lac operon is basically
containing three structural genes which
is like I lack said and loquats which
encodes for the enzymes that are
required by a coli bacterium for
utilization of lactose as a food source
the three enzymes that are found will be
beta galactosidase lacto for me aces now
because Olympus udders are nothing but
that help to convert lactose into usable
form of sugars which is glucose and
lactose permease is basically allow
lactose to gain entry inside bacterial
cell and then conversion can be done now
in an absence of a medium in which
lactose is absent imagine that condition
obviously in that medium the lac
repressor or we can say a protein that
stops this process of protein synthesis
binds to the operator region present on
the lac operon and hence no enzyme is
made once no enzyme is made no it it is
wasted
students this is an example or you can
say this is a diagrammatic example of
black opium now what does it consist of
the it consists of a promoter region it
also consists of an operator region and
the three different gene tell acts a
black wire and the like a or eye region
now how does the process of synthesizing
beta-galactosidase as well as slack for
me is a start
whenever there's lactose present in
media that then your RNA polymerase
which is related to transcription and
translation comes and binds to the
promoter region and we all know that
vents where RNA polymerase comes and
binds to the promoter region at that
time the process of transcription takes
place that is the process to read
messages take place and further the
proteins which is beta galactosidase and
lactose Primus will be synthesized now
in either the condition in which lactose
is not present at that time to the
operator region a repressor protein
comes and binds now once a repressor
protein comes and binds repressor
proteins basically drop the RNA
polymerase from binding to the promoter
region since they shape the operator as
well as the promoter region and hence no
proteins could be synthesized so
students whenever the e coli is not
using lactose as a food source and using
something else as its food source there
is no point that this machinery or this
mechanism needs to work so hence the
repressor proteins avoid the wastage of
energy and prevent the formation of the
enzymes that are required for protein
synthesis I hope you all are clear about
this concept of lactose operon or lac
operon
