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Lactose repressor

Lactose repressor

protein (tetramer of 37 kd subunits) that normally binds with very high affinity to the operator region of the lactose operon and inhibits transcription of the downstream genes by blocking access of the polymerase to the promoter region. When the lactose repressor binds allolactose, its binding to the operator is reduced and the gene set is derepressed.

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Determine whether gene lac I and lac O is functioning?

My sample is treated in 3 ways: No inducer, with lactose , with IPTG. ONPG is used in all sample to determine the beta galactosidase. I know that both lactose and IPTG can associate with lac repressor and cause expression. If the result of these three treatment only with IPTG ...

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by eos
Fri May 09, 2014 11:57 am
Forum: General Discussion
Topic: Determine whether gene lac I and lac O is functioning?
Replies: 0
Views: 1002

Regulation of gene expression in Bacteria

Hi, I'm learning about the regulation of the lactose system in bacteria and came across the following: The lac promotor and repressor are commonly used in expression cloning vectors. But now my question is: Why? Is it because ...

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by Lucanus cervus
Sat Jan 08, 2011 11:03 pm
Forum: Genetics
Topic: Regulation of gene expression in Bacteria
Replies: 2
Views: 2183

Repressor always bound to operator

In a normally functioning lac operon, in prokaryotes, repressor protein binds the operator only when lactose concentration is high. However, consider a mutant where the repressor always binds operator. ...

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by amoeba271
Tue Nov 24, 2009 6:00 am
Forum: Molecular Biology
Topic: Repressor always bound to operator
Replies: 2
Views: 2119

Re: IBO 2003 questions- please help me out

C: The lactose operon of E.coli consists of three genes: lacZ encodes β-galactosidase, lacY encodes ... cell, lacA encodes galactoside-transacetylase. Lac operon is under the control of LacI (repressor), which is inactive in the presence of lactose (inductor). There is a wide diversity ...

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by tittu
Mon May 12, 2008 2:41 pm
Forum: Cell Biology
Topic: IBO 2003 questions- please help me out
Replies: 9
Views: 11205

Re: help with report on Plasmid Properties

... Lac a Lac Z encodes for beta-galactosidase that is a lactase: cleaves lactose (the sugar). Lac y encodes for Galactoside permease that promotes ... represses lac O (negative control): in the presence of glucose, a repressor protein is released, it is able to bind to Lac O DNA sequence only ...

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by Biologista
Fri Oct 26, 2007 6:19 pm
Forum: Molecular Biology
Topic: Re: help with report on Plasmid Properties
Replies: 4
Views: 3736
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