Lac Operon Video Lecture - Biology Class 12 - NEET

the e.coli lack operon is an example of
an inducible set of genes these genes
are responsible for the breakdown of
lactose into sugars used for cellular
metabolism this inducible system also
involves bacterial DNA a repressor
MRNA
and the sugar molecule lactose this
animation will only focus on two of the
three proteins encoded by the lac operon
beta galactosidase and permeates
gene expression can be induced or turned
on when a specific inducer molecule
appears in a Cell
for inducible systems a repressor
molecule prevents gene expression by
binding to the upstream controlling
region
lactose is the lac operon inducer
molecule after first appearing in the
cellular environment lactose passively
enters the e coli cell and binds to the
repressor molecule this binding releases
the repressor from the controlling
region at this point RNA polymerase can
begin transcription of the operon here
we show two of the three lac operon
genes being transcribed into mRNA
ribosomes then bind to the mRNA and the
two proteins are translated the first
protein is beta galactosidase which
breaks down lactose into two simple
sugars the second protein is permeates a
membrane-bound protein when embedded in
the cell membrane permeations to provide
a direct route for the lactose outside
the cell to be imported into the cell
this import occurs at a much greater
rate than the passive transfer we first
observed because translation continues
inside the cell other permease proteins
become embedded in the membrane this
further increases the rate at which
lactose enters the cell beta
galactosidase breaks the cellular
lactose into the simple sugars glucose
and galactose once it's concentration is
greatly reduced the lactose bound to the
repressor are released at this point the
repressor again binds to the controlling
region and gene expression is halted for
all inducible systems like the lac
operon it is the interaction of the
repressor and inducer molecules that
mediate gene expression
you