Eukaryotic Chromosome Structure
Sequence Interspersion
Sequence interspersion - the arrangement of single copy and repetitive
DNAs in eukaryotic organisms; the repetitive DNA is usually from the middle
repetitive class
Short period interspersion
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The prominent arrangement of single copy and repetitive DNA in eukaryotic
organisms
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This arrangement is characterized by:
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repeated sequences 100-200 bp in length interspersed among single copy sequences
that are 1000-2000 bp in length.
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This arrangement is found in animals, fungi and plants. (SC= single copy;
R=repeat)
SC R SC R SC R SC R SC
--------XXXXXX---------XXXXXXX-----------XXXXXXX---------XXXXXXX----------
150 bp 1500 bp
Long-period interspersion
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This is characterized by:
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5000 bp stretches of repeated sequences interspersed within regions of 35,000
bp of single copy DNA
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Drosophila is the principle example of this uncommon sequence arrangement
Single copy Repeat Single copy
---------------------------------------XXXXXXX------------------------------------
35,000 bp 5000 bp