This section focuses on observing differences examined biochemically to determine evolutionary relationships.
Species that are closely related are expected to have fewer differences in amino acid sequences of particular proteins than species that are distantly related. The longer periods of divergence the more likely that there will be changes in amino acids sequences.
By comparing DNA sequences through sequencing we should be able to determine evolutionary relationships. If evolution has occurred then the genes present in an ancestral species will also be present in members of a related group due to conservation. This does not mean the sequences will be identical, but they will be fairly similar.
DNA can also be compared on the basis of chromosomes through looking at banding patterns and through the use of chromosomal painting (which involves the use of probes that can be applied to chromosomes of other species)
DNA hybirdisation provides evidence on the relatedness between two species.
DNA hybridization requires DNA to be removed from two species to be compared which are separated by heat, to allow separation.
Separated strands area allowed to pair between the species and the degree of pairing (hybridization) depends on the relationships between species.
The closer related the greater the pairing.
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