DNA microarrays: Difference between revisions
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DNA microarrays are used in [[ | DNA microarrays are used in [[Functional genomics]] to determine the differences in [[Gene expression]] levels between a sample and control cell<ref name="Daniel L. Hartl">Daniel L. Hartl, Elizabeth W. Jones (2009) Genetics Analysis of Genes and Genomes 7th Edition USA, Jones and Bartlett Publishers.</ref>. The sample cell can be from a different tissue, at a different stage of development, at a different stage of the cell cycle, or be under different conditions (for example, exposure to a [[Toxin]])<ref name="Daniel L. Hartl">Daniel L. Hartl, Elizabeth W. Jones (2009) Genetics Analysis of Genes and Genomes 7th Edition USA, Jones and Bartlett Publishers.</ref>. The DNA microarray consists of a flat surface to which [[Oligonucleotides]] are bound<ref name="Daniel L. Hartl">Daniel L. Hartl, Elizabeth W. Jones (2009) Genetics Analysis of Genes and Genomes 7th Edition USA, Jones and Bartlett Publishers.</ref>. These [[Oligonucleotides]] are complementary to specific [[CDNA]] sequences<ref name="Daniel L. Hartl">Daniel L. Hartl, Elizabeth W. Jones (2009) Genetics Analysis of Genes and Genomes 7th Edition USA, Jones and Bartlett Publishers.</ref>. The [[MRNA]] molecules within the sample and the control are converted into labelled [[CDNA]] molecules with the use of [[Reverse transcriptase]] and fluorescently-labelled [[Nucleotides]]<ref name="Daniel L. Hartl">Daniel L. Hartl, Elizabeth W. Jones (2009) Genetics Analysis of Genes and Genomes 7th Edition USA, Jones and Bartlett Publishers.</ref>. For example, the [[CDNA]] of the sample can have a red fluorescence label whereas the [[CDNA]] of the control can have a green fluorescence label<ref name="Daniel L. Hartl">Daniel L. Hartl, Elizabeth W. Jones (2009) Genetics Analysis of Genes and Genomes 7th Edition USA, Jones and Bartlett Publishers.</ref>. The DNA microarray is exposed to the [[CDNA]] mixture and unbound [[CDNA]] is washed away<ref name="Daniel L. Hartl">Daniel L. Hartl, Elizabeth W. Jones (2009) Genetics Analysis of Genes and Genomes 7th Edition USA, Jones and Bartlett Publishers.</ref>. The resultant DNA microarray consists of spots of colour that is imaged using a [[Confocal fluorescence scanner]]<ref name="Daniel L. Hartl">Daniel L. Hartl, Elizabeth W. Jones (2009) Genetics Analysis of Genes and Genomes 7th Edition USA, Jones and Bartlett Publishers.</ref>. The colour of the spot is indicative of the differences in [[Gene expression]] between the sample and control<ref name="Daniel L. Hartl">Daniel L. Hartl, Elizabeth W. Jones (2009) Genetics Analysis of Genes and Genomes 7th Edition USA, Jones and Bartlett Publishers.</ref>. Following the colour scheme above, a red spot indicates that the sample is overexpressing that particular [[Gene]] compared to the control; a green spot indicates that the sample is underexpressing that particular [[Gene]] compared to the control; and a yellow spot indicates that there is equal [[Gene expression]] in the sample and control<ref name="Daniel L. Hartl">Daniel L. Hartl, Elizabeth W. Jones (2009) Genetics Analysis of Genes and Genomes 7th Edition USA, Jones and Bartlett Publishers.</ref>. However, the range of colours is not as discrete as suggested here but is more of a spectrum covering intermediate differences in [[Gene expression]]<ref name="Daniel L. Hartl">Daniel L. Hartl, Elizabeth W. Jones (2009) Genetics Analysis of Genes and Genomes 7th Edition USA, Jones and Bartlett Publishers.</ref>. DNA microarrays are not so useful in determining [[Gene]] function but can ascertain which genes may have the same regulatory mechanisms<ref name="Daniel L. Hartl">Daniel L. Hartl, Elizabeth W. Jones (2009) Genetics Analysis of Genes and Genomes 7th Edition USA, Jones and Bartlett Publishers.</ref>. | ||
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Revision as of 18:53, 13 November 2011
DNA microarrays are used in Functional genomics to determine the differences in Gene expression levels between a sample and control cell[1]. The sample cell can be from a different tissue, at a different stage of development, at a different stage of the cell cycle, or be under different conditions (for example, exposure to a Toxin)[1]. The DNA microarray consists of a flat surface to which Oligonucleotides are bound[1]. These Oligonucleotides are complementary to specific CDNA sequences[1]. The MRNA molecules within the sample and the control are converted into labelled CDNA molecules with the use of Reverse transcriptase and fluorescently-labelled Nucleotides[1]. For example, the CDNA of the sample can have a red fluorescence label whereas the CDNA of the control can have a green fluorescence label[1]. The DNA microarray is exposed to the CDNA mixture and unbound CDNA is washed away[1]. The resultant DNA microarray consists of spots of colour that is imaged using a Confocal fluorescence scanner[1]. The colour of the spot is indicative of the differences in Gene expression between the sample and control[1]. Following the colour scheme above, a red spot indicates that the sample is overexpressing that particular Gene compared to the control; a green spot indicates that the sample is underexpressing that particular Gene compared to the control; and a yellow spot indicates that there is equal Gene expression in the sample and control[1]. However, the range of colours is not as discrete as suggested here but is more of a spectrum covering intermediate differences in Gene expression[1]. DNA microarrays are not so useful in determining Gene function but can ascertain which genes may have the same regulatory mechanisms[1].