LacZα gene: Difference between revisions
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The LacZα gene is one of the [[Structural Gene|structural genes]] present on the [[Lac operon|Lac Operon]] in [[Escherichia coli|Escherichia]] coli [[Bacteria|bacteria]]<ref>Hartl, D.L., Ruvolo, M. 2012. Genetics: Analysis of Genes and Genomes, Eighth Edition. Burlington, MA: Jones &amp;amp;amp;amp; Bartlett Learning. Page 394.</ref>. When [[Transcription|transcribed]] by [[RNA Polymerase|RNA polymerase]], the LacZα gene codes for [[Β-galactosidase|β-galactosidase]], an [[Enzyme|enzyme]] responsible for the [[Hydrolysis|hydrolysis]] of β-galactosides (e.g. [[Lactose|lactose]])<ref>Kalnins, A et al. 1983. Sequence of the lacZ gene of Escherichia coli. The EMBO Journal, 2,4, 593-597.</ref><ref>Hartl, D.L., Ruvolo, M. 2012. Genetics: Analysis of Genes and Genomes, Eighth Edition. Burlington, MA: Jones &amp;amp;amp;amp; Bartlett Learning. Page 391.</ref>. On the lac operon, the LacZα gene exists between the operator region and the [[LacY gene|LacY]] gene<ref>Hardin, J. et al. 2012. Becker's World of the Cell, Eighth Edition. Boston, MA: Benjamin Cummings. Page 712.</ref>. | |||
<span style="line-height: 1.5em;">The LacZα gene is only transcribed in certain conditions. Lactose must be present when [[Glucose|glucose]] is unavailable due to the presence of a repressor protein ([[Lac repressor|Lac repressor]]) on the operator region of the Lac Operon<ref>Hardin, J. et al. 2012. Becker's World of the Cell, Eighth Edition. Boston, MA: Benjamin Cummings. Page 713.</ref>. This repressor protein prevents RNA polymerase from binding to the operator region; hence transcription of the structural genes cannot take place.</span> | <span style="line-height: 1.5em;">The LacZα gene is only transcribed in certain conditions. Lactose must be present when [[Glucose|glucose]] is unavailable due to the presence of a repressor protein ([[Lac repressor|Lac repressor]]) on the operator region of the Lac Operon<ref>Hardin, J. et al. 2012. Becker's World of the Cell, Eighth Edition. Boston, MA: Benjamin Cummings. Page 713.</ref>. This repressor protein prevents RNA polymerase from binding to the operator region; hence transcription of the structural genes cannot take place.</span> | ||
Fragments of the LacZα gene are also used in the [[Recombinant DNA Technology|recombinant DNA technologies]] to identify recombinant plasmids (a [[Plasmid|plasmid]] with a new section of [[DNA|DNA]] added) in bacterial colonies. New genes are inserted into the [[Multiple cloning site|multiple cloning site]] (MCS), which lies in a region of the LacZα gene fragment. Therefore, recombinant bacteria produce β-galactosidase (as the LacZα gene is not disrupted), whereas the non-recombinant bacteria do not (as the LacZα gene is disrupted, therefore inactive). Hence, due to the LacZα gene, recombinant bacteria can be easily detected<ref>Hartl, D.L., Ruvolo, M. 2012. Genetics: Analysis of Genes and Genomes, Eighth Edition. Burlington, MA: Jones &amp; Bartlett Learning. Page 450.</ref>.<br> | Fragments of the LacZα gene are also used in the [[Recombinant DNA Technology|recombinant DNA technologies]] to identify recombinant plasmids (a [[Plasmid|plasmid]] with a new section of [[DNA|DNA]] added) in bacterial colonies. New genes are inserted into the [[Multiple cloning site|multiple cloning site]] (MCS), which lies in a region of the LacZα gene fragment. Therefore, recombinant bacteria produce β-galactosidase (as the LacZα gene is not disrupted), whereas the non-recombinant bacteria do not (as the LacZα gene is disrupted, therefore inactive). Hence, due to the LacZα gene, recombinant bacteria can be easily detected<ref>Hartl, D.L., Ruvolo, M. 2012. Genetics: Analysis of Genes and Genomes, Eighth Edition. Burlington, MA: Jones &amp;amp;amp;amp; Bartlett Learning. Page 450.</ref>.<br> | ||
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Latest revision as of 06:45, 29 November 2013
The LacZα gene is one of the structural genes present on the Lac Operon in Escherichia coli bacteria[1]. When transcribed by RNA polymerase, the LacZα gene codes for β-galactosidase, an enzyme responsible for the hydrolysis of β-galactosides (e.g. lactose)[2][3]. On the lac operon, the LacZα gene exists between the operator region and the LacY gene[4].
The LacZα gene is only transcribed in certain conditions. Lactose must be present when glucose is unavailable due to the presence of a repressor protein (Lac repressor) on the operator region of the Lac Operon[5]. This repressor protein prevents RNA polymerase from binding to the operator region; hence transcription of the structural genes cannot take place.
Fragments of the LacZα gene are also used in the recombinant DNA technologies to identify recombinant plasmids (a plasmid with a new section of DNA added) in bacterial colonies. New genes are inserted into the multiple cloning site (MCS), which lies in a region of the LacZα gene fragment. Therefore, recombinant bacteria produce β-galactosidase (as the LacZα gene is not disrupted), whereas the non-recombinant bacteria do not (as the LacZα gene is disrupted, therefore inactive). Hence, due to the LacZα gene, recombinant bacteria can be easily detected[6].
References
- ↑ Hartl, D.L., Ruvolo, M. 2012. Genetics: Analysis of Genes and Genomes, Eighth Edition. Burlington, MA: Jones &amp;amp;amp; Bartlett Learning. Page 394.
- ↑ Kalnins, A et al. 1983. Sequence of the lacZ gene of Escherichia coli. The EMBO Journal, 2,4, 593-597.
- ↑ Hartl, D.L., Ruvolo, M. 2012. Genetics: Analysis of Genes and Genomes, Eighth Edition. Burlington, MA: Jones &amp;amp;amp; Bartlett Learning. Page 391.
- ↑ Hardin, J. et al. 2012. Becker's World of the Cell, Eighth Edition. Boston, MA: Benjamin Cummings. Page 712.
- ↑ Hardin, J. et al. 2012. Becker's World of the Cell, Eighth Edition. Boston, MA: Benjamin Cummings. Page 713.
- ↑ Hartl, D.L., Ruvolo, M. 2012. Genetics: Analysis of Genes and Genomes, Eighth Edition. Burlington, MA: Jones &amp;amp;amp; Bartlett Learning. Page 450.