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How FISH works

FISH is a type of DNA hybridisation, which uses the ability of DNA to stick to a 'complementary copy' of itself. The chemical letter A always pairs up with T, and C with G. To carry out FISH, scientists first unzip the DNA that makes up both the tagged gene and the chromosomes into two separate strands. So when the fluorescently tagged copy of the gene is put on to the microscope slide, it will stick to its 'complementary copy' on one of the chromosomes.

How FISH works

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