DNA Hybridisation

Mutations

Due to mutations, the sequence of two organisms with a common ancestor will become more dissimular over time.

One way to determine simularities in the DNA of different organisms is by using DNA hybridisation.

DNA hybridisation

• DNA from 2 species is extracted and purified.
• DNA from one of the species is labelled using radioactive or fluorescent marker to it.
• Both sets of DNA is heated to seperate the strands (removing H bonds)
• The mixture is cooled to allow the strands to combine with strands with complementary organic bases.
• Some double strands will have one strand of each species (one labelled, one unlabelled.)
• These hybrid strands are seperated from the mixture.
• These are heated at different stages.
• If the species are closely related then the temperature taken to split the two strands is higher.