Analyze the following genotypes of the Lac Operon in E....

Analyze the following genotypes of the Lac Operon in E. coli. In each case, determine whether Beta-galactosidase (enzyme that digests lactose) and permease (membrane channel that brings lactose into the cell) would be made in the presence or absence of lactose. Simply select 'YES' if the enzyme is made or 'NO' if it is not . (Refer to the Lac Operon diagram for the meaning of the letters in the genotypes. Remember a "plus" superscript indicates normal functioning part of operon or repressor gene, a "minus" indicates loss of function, "O^C" means "operator-constitutive", and "I^S" means "super-repressor") Absence of Lactose Presence of Lactose Genotype B-gal Permease B-gal Permease I^S P^+ O Z^+ Y^- / I^+ P^+ O^C Z^- Y^+ I^+ P^+ O^C Z^+ Y^+ / I^+ P^- O Z^- Y^- I^+ P^- O^C Z^- Y^+ / I^- P^+ O Z^+ Y^- I^+ P^+ O Z^- Y^+ / I^- P^+ O Z^+ Y^-

Transcript

0:00 Hello everyone.

00:01 In this question we will be talking about the lac operon gene.

00:06 So this here is the construct of the lac operon gene, in which there is presence of the promoter, the operator region and the laci gene.

00:19 Then there is promoter region, the operator region lack z gene and the lack y gene and lack y gene and lack gene.

00:31 So this lactose, so this lapoperon is basically a inducible operon.

00:39 This rna polymerase binds to the promoter region of the lap -i gene and transcribes it.

00:46 And then the transcription occurs and then we have our repressor protein.

00:51 So this repressor will bind to the operator region and due to which the rna polymeries cannot perform the transcription.

01:00 So this here takes place when the lactose concentration is low and when the glucose concentration is high.

01:09 But if we reverse this case, if the lactose concentration is high and glucose concentration is low, then the allosteic form of the lactose, that is the aloe lactose will bind to the repressor and due to which this repressor is now inactive and it cannot bind to the operator.

01:36 So now the rna polymerase will be easily able to transcribe the lat gene here and this lacz gene codes for the beta galactocytes which break down the lactose into glucose and gals the lack -wide gene codes for the beta -gal fermase which allow the entry of the lactose into the cell.

02:08 And this lack a is beta -galactocytase transacetylase, which detoxifies the compounds.

02:18 So here basically if there are certain mutations, like if there is a mutation which is i minus mutation, so this lack i gene basically will not be able to bind to the operator and due to which the transcription will be constituted.

02:40 Whereas if there is i s mutation here, this changes the repressor so that it can no longer bind to the inducer.

02:51 And so now the allolectors cannot bind to this and cannot inhibit the activity of repressors.

02:57 So that is why here our lap operon will be always off.

03:03 It is uninducible...

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