The genetic difference between two Drosophila species, D. heteroneura and D. silvestris, as measured by nucleotide diversity, is about 1.8 percent. The difference between chimpanzees (Pan troglodytes) and humans (H. sapiens) is about the same, yet the latter species is classified in a different genera. In your opinion, is this valid? Explain why.
- 1. Introduction to Genetics51m
- 2. Mendel's Laws of Inheritance3h 37m
- 3. Extensions to Mendelian Inheritance2h 41m
- 4. Genetic Mapping and Linkage2h 28m
- 5. Genetics of Bacteria and Viruses1h 21m
- 6. Chromosomal Variation1h 48m
- 7. DNA and Chromosome Structure56m
- 8. DNA Replication1h 10m
- 9. Mitosis and Meiosis1h 34m
- 10. Transcription1h 0m
- 11. Translation58m
- 12. Gene Regulation in Prokaryotes1h 19m
- 13. Gene Regulation in Eukaryotes44m
- 14. Genetic Control of Development44m
- 15. Genomes and Genomics1h 50m
- 16. Transposable Elements47m
- 17. Mutation, Repair, and Recombination1h 6m
- 18. Molecular Genetic Tools19m
- 19. Cancer Genetics29m
- 20. Quantitative Genetics1h 26m
- 21. Population Genetics50m
- 22. Evolutionary Genetics29m
PEG10 (paternally expressed gene 10) is a paternally expressed gene (meaning only the paternal allele is expressed) that has an essential role in the formation of the placenta of the mouse. In the mouse genome, the PEG10 gene is flanked by the SGCE and PPP1R9A genes. To study the origin of PEG10, you examine syntenic regions spanning the SGCE and PPP1R9A loci in the genomes of several vertebrates, and you note that the PEG10 gene is present in the genomes of placental and marsupial mammals but not in the platypus, chicken, or fugu genomes.
The green bars in the figure indicate the exons of each gene. The gray bars represent LINEs and SINEs, and the blue bars represent long terminal repeat (LTR) elements of retrotransposons. Solid black diagonal lines link introns, and dashed black lines connect orthologous exons. Arrowheads indicate direction of transcription.
Using the predicted protein sequence of PEG10, you perform a tblastn search for homologous genes and find that the most similar sequences are in a class of retrotransposons (the sushi-ichi retrotransposons). Propose an evolutionary scenario for the origin of the PEG10 gene, and relate its origin to its biological function. <>
Comparative Genomics practice set
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