Blue/white Selection: Difference between revisions

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A technique usually used to identify [[Recombinant|recombinant]] colonies on agar for use in [[PCR|PCR]].  
Blue/White selection is a technique that can be used to identify [[Recombinant|recombinant]] colonies on agar for use in [[PCR|PCR]].  


''[[Escherichia_coli|Escherichia coli]]'' cells are often used as hosts in this technique, containing the β-peptide in the [[Genome|genome]]. The α-peptide of [[Β-galactosidase|β-galactosidase]] is expressed in the [[Plasmid|plasmid]], when [[DNA|DNA]] is inserted into the [[LacZα gene|lacZα gene]] it disrupts the formation of [[Β-galactosidase|β-galactosidase]]. β-galactosidase is needed to [[Metabolism|metabolise]] [[X-gal|X-gal into]] a bright blue product, therefore the recombinant [[Plasmid|plasmid]] containing the [[DNA|DNA]] insert will not be able to form the blue product and so all colonies with recombinant [[Plasmid|plasmid]] would be white.
''[[Escherichia coli|Escherichia coli]]'' cells are often used as hosts in this technique, containing the β-peptide in the [[Genome|genome]]. The α-peptide of [[Β-galactosidase|β-galactosidase]] is expressed in the [[Plasmid|plasmid]], when [[DNA]] is inserted into the [[LacZα gene|lacZα gene]], preventing the plasmid from being able to transcribe and therefore express [[Β-galactosidase|β-galactosidase]].  
 
When β-galactosidase is expressed, the substrate X-gal can be metabolised, producing a blue colony. However, the recombinant [[Plasmid|plasmid]] that contains the [[DNA|DNA]] insert will not be able to produce blue colonies and instead will produce white colonies.

Latest revision as of 14:46, 21 October 2018

Blue/White selection is a technique that can be used to identify recombinant colonies on agar for use in PCR.

Escherichia coli cells are often used as hosts in this technique, containing the β-peptide in the genome. The α-peptide of β-galactosidase is expressed in the plasmid, when DNA is inserted into the lacZα gene, preventing the plasmid from being able to transcribe and therefore express β-galactosidase.

When β-galactosidase is expressed, the substrate X-gal can be metabolised, producing a blue colony. However, the recombinant plasmid that contains the DNA insert will not be able to produce blue colonies and instead will produce white colonies.