Principle and use of microarrays
Microarrays are used to compare gene expression in 2 genetically idential cells. This difference in expression is usually due to different conditions around (no O2-> diff. genes expressed). Do to this, the relation between mRNA quantity and expression is used. The mRNA is extracted and then a RT PCR is conducted. Here, the 2 different cells get different fluorescent labels by adding labeled nucleotides. The old stand of mRNA is now degraded, and we have 2 tubes with 2 sscDNA libraries. Both cDNA libraries are then mixed and put on a microarray chip, containing all genes of the organism fixed, ready to hybridise (join single, compl. cDNA strand). The added sscDNA hybridises. Now the fluorescens is measured and compared. some genes are now green, others red. -> conclusions about expression.