A mutation occurs in the operator site within the lac operon of E.coli which prevents binding to the operator of the protein encoded by the lac i gene. What will be the likely effect of this mutation (assume glucose to be absent)? ß-galactosidase will be produced only in the presence of galactose ß-galactosidase will be produced only in the absence of lactose ß-galactosidase will not be produced in significant levels regardless of the presence of lactose ß-galactosidase will be produced continuously regardless of the presence of lactose ß-galactosidase will be produced only in the presence of lactose
Question
A mutation occurs in the operator site within the lac operon of E.coli which prevents binding to the operator of the protein encoded by the lac i gene. What will be the likely effect of this mutation (assume glucose to be absent)? ß-galactosidase will be produced only in the presence of galactose ß-galactosidase will be produced only in the absence of lactose ß-galactosidase will not be produced in significant levels regardless of the presence of lactose ß-galactosidase will be produced continuously regardless of the presence of lactose ß-galactosidase will be produced only in the presence of lactose
Solution
The likely effect of this mutation would be that ß-galactosidase will be produced continuously regardless of the presence of lactose.
Here's why:
The lac operon is a set of genes in E.coli that are responsible for the metabolism of lactose. The lac i gene produces a repressor protein that binds to the operator site, preventing transcription of the lac operon and thus production of ß-galactosidase, an enzyme that breaks down lactose.
If a mutation occurs in the operator site that prevents the repressor protein from binding, then the lac operon will not be repressed. This means that the genes will be transcribed and ß-galactosidase will be produced, regardless of whether lactose is present or not.
This is because the normal function of the repressor protein is to stop production of ß-galactosidase when lactose is not present (since it's not needed). But if the repressor can't bind, then this "off switch" is essentially broken, and ß-galactosidase will be produced all the time.
Similar Questions
In E. coli, transcription of the lac operon would be increased by:Group of answer choicesA missense mutation that disrupts the activity of the catabolite activator protein (CAP).A mutation in the lacI repressor gene that increases the affinity of the repressor for allolactose.A mutation in the lacI repressor gene that increases the affinity of the repressor for the lac operator.The presence of glucose in the growth medium.
What is most likely to happen in E. coli if a missense mutation disrupts a critical codon in the trpR gene?Group of answer choicesThe trp operon is expressed only when tryptophan is absent.The genes in the trp operon are never expressed.The genes in the trp operon are transcribed but not translatedThe genes in the trp operon are always expressed
A missense mutation in the nucleotide sequence of a gene definitely has the effect of: A) The substitution of an amino acid in the protein encoded by the gene B) The production of a protein longer than normal C) The production of a protein shorter than normal D) The death of the cell in which the mutation occurred E) The failure to produce the protein encoded by the gene
An increase in Beta-galactosidase occurs in E. coli cells in response to an increase in which effector molecule A. Galaktose / Galactose B. Glukose / Glucose C. Laktose / Lactose D. Allolaktose / Allolactose
Which of the following is not a possible effect of a mutation?any of the above can occuradds a function to a proteinlowers the amount of a proteinprevents a protein from forming
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