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Junk DNA domestic imported (e.g., dead genes) (e.g., retroviruses)

Junk DNA domestic imported (e.g., dead genes) (e.g., retroviruses). 1.5%. Exons. Introns ( junk ). Intergenic regions ( junk ). The genome is empty. Junk DNA = 98.5%. Why do similar species have different genome sizes?. Creation of Junk. Disposal

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Junk DNA domestic imported (e.g., dead genes) (e.g., retroviruses)

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  1. Junk DNA domestic imported (e.g., dead genes) (e.g., retroviruses)

  2. 1.5% Exons Introns (junk) Intergenic regions (junk) The genome is empty.

  3. Junk DNA = 98.5%

  4. Why do similar species have different genome sizes? Creation of Junk Disposal of Junk

  5. Hawaiian cricket Drosophila 165 MB Laupala 2,000 MB

  6. Segments of DNA that do not repeat themselves are referred to assingle-copy or uniqueDNA.

  7. The proportion of the genome taken up by repetitive sequences varies widely among taxa: Yeast ~20% Midge (Chironomus tetans) ~5% Newt (Necturus masculosus) ~90% Humans ~50%

  8. Localized repeated sequences Most eukaryotic genomes contain tandemly arrayed, highly repetitive DNA sequences. These localized repetitive sequences can account for major portions of the genome.

  9. Kangaroo Rat(Dipodomys ordii) 50% of the genome consists of: AAG 2.4  109 times TTAGGG 2.2  109 times ACACAGCGGG 1.2  109 times

  10. 40% of the Drosophila virilis genome consists of: ACAAACT 1.1  107 times ATAAACT 3.6  106 times ACAAATT 3.6  106 times

  11. 35% of the genome of Absidia glauca, which is only 9 times larger than that of E. coli, is made of repetitive DNA.

  12. Satellite DNA may be extremely GC-rich or extremely AT-rich

  13. Low GC content in satellites: 1% in Cancer gracilis and C. antennarius.

  14. High GC content in satellites: 73% in Leishmania infantum and Chironomus plumosus

  15. Satellite DNA as fraction of total genome Mammals 5-30% Plants 5-40%

  16. 60% of the genome of Drosophila nasutoides consists of satellite DNA.

  17. 15% of the genome.

  18. Simple-tandem repetitive sequences _______________________________________________________ Class Repeat size Array size (bp) (number of units) _______________________________________________________ Satellites 2-2,000 >1,000 Minisatellites 9-100 10-100 Microsatellites 1-6 10-150 _______________________________________________________

  19. Minisatellites & microsatellites are used in DNA fingerprinting (Variable Number Tandem Repeats, VNTR)

  20. Dispersed repeats (1) SINEs (2) LINEs (3) retrovirus-like and retrotransposon-like elements (4) DNA-mediated transposable fossils

  21. Mobile elements or ex-mobile elements in the human genome.

  22. Dispersed repetitive sequences in the human genome LINE1 600,000 15% LINE2 271,000 5% Alu 1,300,000 10% MIR 400,000 3% Retroelements 5% DNA-transposable elements 2% unclassified 60,000 1%

  23. >1/3 of the human genome is derived from mobile elements. The vast majority of these sequences no longer possess the ability to move.

  24. Feature Name Number (base pairs) (%) Alu Repeats20,188 5621998 16.3 CpG Islands 536 575970 1.7 HERV Repeats 255 160697 0.5 Line1 Repeats 8043 3256913 9.4 Line2 Repeats 6381 1273571 3.7 LTR Repeats 848 256412 0.7 MER Repeats 3757 763390 2.2 MIR Repeats 8426 1063419 3.1 MLT Repeats 2483 605813 1.8 Other Repeats 2313 625562 1.8 Other Tandem Repeats 305 102245 0.3 Dinucleotide Repeats 1775 133765 0.4 Trinucleotide Repeats 166 18410 0.1 Quadranucleotide Repeats 404 47691 0.1 Pentanucleotide Repeats 16 1612 0.0 THE Repeats 304 93159 0.3 Chromosome 22 42.4%

  25. 98% of the variation in genome size in apes is explained by the variation in repetitive sequences (heterochromatin).

  26. 1.5% A summary

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