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08:18An interactive Web site for the Human Proteome Map (HPM) is available at http://www.humanproteomemap.org. Visit this site, and then answer the question.
Use the 'Query' tab and select the 'Gene family' dropdown menu to do a search on the distribution of proteins encoded by a pathway of interest to you. Search in fetal tissues, adult tissues, or both.
Researchers have compared candidate loci in humans and rats in search of loci in the human genome that are likely to contribute to the constellation of factors leading to hypertension [Stoll, M., et al. (2000). Genome Res. 10:473–482]. Through this research, they identified 26 chromosomal regions that they consider likely to contain hypertension genes. How can comparative genomics aid in the identification of genes responsible for such a complex human disease? The researchers state that comparisons of rat and human candidate loci to those in the mouse may help validate their studies. Why might this be so?
Homology can be defined as the presence of common structures because of shared ancestry. Homology can involve genes, proteins, or anatomical structures. As a result of 'descent with modification,' many homologous structures have adapted different purposes.
List three anatomical structures in vertebrates that are homologous but have different functions.
Homology can be defined as the presence of common structures because of shared ancestry. Homology can involve genes, proteins, or anatomical structures. As a result of 'descent with modification,' many homologous structures have adapted different purposes.
Under what circumstances might one expect proteins of similar function to not share homology? Would you expect such proteins to be homologous at the level of DNA sequences?
Comparisons between human and chimpanzee genomes indicate that a gene that may function as a wild-type or normal gene in one primate may function as a disease-causing gene in another [The Chimpanzee Sequencing and Analysis Consortium (2005). Nature 437:69–87]. For instance, the PPARG locus (regulator of adipocyte differentiation) is a wild-type allele in chimps but is clearly associated with Type 2 diabetes in humans. What factors might cause this apparent contradiction? Would you consider such apparent contradictions to be rare or common? What impact might such findings have on the use of comparative genomics to identify and design therapies for disease-causing genes in humans?
Genomic sequencing has opened the door to numerous studies that help us understand the evolutionary forces shaping the genetic makeup of organisms. Using databases containing the sequences of 25 genomes, scientists examined the relationship between GC content and global amino acid composition [Kreil, D. P., and Ouzounis, C. A. (2001) Nucl. Acids Res. 29:1608–1615]. They found that it is possible to identify thermophilic species on the basis of their amino acid composition alone, which suggests that evolution in a hot environment selects for a certain whole organism amino acid composition. In what way might evolution in extreme environments influence genome and amino acid composition? How might evolution in extreme environments influence the interpretation of genome sequence data?
