Summary
Slides carrying thousands of probes that measure expression of many genes at once.
In depth
Cells' mRNA is converted to labelled cDNA and hybridised to slides spotted with gene probes; fluorescence intensity shows expression levels. Largely replaced by RNA-seq, but still used for SNP genotyping.
Hybridisation depends on sequence complementarity and stringency. Data are normalised and analysed statistically to find differentially expressed genes. Clustering reveals co-expressed genes.
Example: gene expression signatures predict cancer prognosis.
A DNA microarray is a glass slide or chip with thousands of spots, each holding a DNA probe for a different gene. RNA from a sample is converted to labelled cDNA and hybridised to the chip; fluorescence intensity at each spot shows how active that gene is.
Two-colour arrays compare healthy and diseased tissue directly. They were used to classify cancers, discover gene networks and detect SNPs. Today RNA-seq has largely replaced them for expression because it detects novel transcripts and has a wider range.
Example: gene-expression patterns separate breast cancer subtypes.
Remember: arrays only find what they have probes for.
Frequently asked questions
What is DNA Microarrays?
Slides carrying thousands of probes that measure expression of many genes at once.
Which area of biology covers DNA Microarrays, and how advanced is it?
DNA Microarrays is one of the 56 topics in Biotechnology & Genomics. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include RNA-Seq, Reporter Genes, Southern, Northern and Western Blots.
Can you give an example of DNA Microarrays?
Microarrays classified breast cancer subtypes.
What should I learn before DNA Microarrays?
Work through the Beginner topics in Biotechnology & Genomics first, such as Biotechnology, Genetic Engineering, Selective Breeding, then return to DNA Microarrays. Intermediate topics assume the Beginner vocabulary.
What topics are related to DNA Microarrays?
The closest topics to DNA Microarrays are RNA-Seq, Reporter Genes, Southern, Northern and Western Blots, Machine Learning in Biology. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand DNA Microarrays?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for DNA Microarrays. To practise the whole of Biotechnology & Genomics, use the Biotechnology & Genomics quiz.
How is DNA Microarrays different from RNA-Seq?
DNA Microarrays: Slides carrying thousands of probes that measure expression of many genes at once. RNA-Seq: Sequencing of cDNA from RNA to quantify gene expression and discover transcripts across the genome. Read both side by side and note what each one explains.
How should I study DNA Microarrays step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with RNA-Seq and explain the difference aloud. Finally, take the Biotechnology & Genomics quiz and come back to this page for any question you miss.