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When organisms evolve its not only their visible, internal and external features that change, but also the molecules of which they are made
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It follows that changes in the
features of a species are due to changes in its DNA
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The variety within a characteristic depends on the number and variety of alleles of
that gene (plus environmental influences)
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Due to mutations, the sequences of nucleotide bases in the DNA of
the new species will change
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As a result, we would expect
species that are more closely related to show similarity in
their DNA than species that are more distantly related
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This has its limitations because a large number of them We can measure DNA diversity and therefore genetic diversity by comparing the base sequence of mRNA
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They are polygenic
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Often difficult to disComparison of amino acid sequences in Proteins:
tinguish one from another and characteristics can also be
Genetic diversity within and between species can be
modified by the environment
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their proteins as these are determined by mRNA which
Comparison of DNA base sequences:
in turn is determined by DNA
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In computer sysalso reflect how closely related they are
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This can be
guanine (yellow)
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ses
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Analysis of these allows us
to compare one species with another or one individual from
another of the same species to determine how diverse they
are
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Establishing Relationships:
Using graphs to compare data
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Such as albumin in the blood
serum of another:
1
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Species B produces antibodies specific to all
antigen sites on the albumin from species A

3
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Serum from species B is mixed with serum
from the blood of a third species C (various
other mammals)

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The response is the formation of a precipitate

The greater the number of similar antigens, the
more precipitate is formed and the more closely
the species ae related
The fewer the number of similar antigens, the less
precipitate is formed and the more distantly the
species are related

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