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Systems Biology – the global study of multiple components of biological systems and their interactions New approach to studying biological systems has made possible Sequencing genomes High-throughput platform development Development of powerful computational tools The use of model organisms Comparative genomics Changes in biology, genetics and genomics from human genome sequence Genetics parts list Speeds gene-finding and gene-function analysis Sequence identification in second organism through homology Gene function in one organism helps understand function in another for orthologous and paralogous genes Genes often encode one or more protein domains Ready access to identification of known human polymorphism Speeds mapping of new organisms by comparison e.g., mouse and human have high similarity in gene content and order How transcription factor protein domains have expanded in specific lineages Fig. 10.14 Conserved segments of syntenic blocks in human and mouse genomes Fig. 10.15 Major insights from human and model organism sequences Approximately 40,000 human genes Genes encode noncoding RNA or proteins Repeat sequences are > 50% of genome Distinct types of gene organization Combinatorial strategies amplify genetic information and increase diversity Evolution by lateral transfer of genes from one organism to another Males have twofold higher mutation rate than females Human races have very few unique distinguishing genes All living organisms evolve from a common ancestor Questions Remain about the Human Genome Difficult to precisely estimate number of genes at this time Full genome not accurately sequenced Small genes are hard to identify Some genes are rarely expressed and do not have normal codon usage patterns – thus hard to detect Protein coding genes generate the proteome Proteome – collective translation of 30,000 protein coding genes into proteins Complexity of proteome increase from yeast to humans More genes Shuffling, increase, or decrease of functional modules More paralogs Alternative RNA splicing – humans exhibit significantly more Chemical modification of proteins is higher in humans Examples of domain accretions in chromatin proteins Fig. 10.16 Number of distinct domain architectures in four eukaryotic genomes Fig. 10.17 Repeat sequences fall into five classes Transposon-derived repeats Processed pseudogenes SSRs Segmental duplications of 10-300 kb Blocks of repeated sequences at centromere, telomeres and other chromosomal features Gene organization of genome Gene families Gene-rich regions Closely related genes clustered or dispersed Functional or chance events? Gene deserts Span 144 Mb or 3% of genome Contain regions difficult to identify? e.g., big genes – nuclear transcript spans 500 kb or more with very large introns (exons < 1% of DNA) Class II region of human major histocampatibility complex contains 60 genes in 700 kb Fig. 10.20 Lateral transfer of genes > 200 human genes may arise by transfer from organisms such as bacteria Lateral transfer is direct transfer of genes from one species into the germ line of another Twofold higher mutation rate in males Comparison of X and Y chromosomes Same may be true for autosomes, but difficult to measure Majority of human mutation arise in males Males give rise to more defects, but also more diversity Human Genome Project has changed the potential for predictive/preventive medicine Provided access to DNA polymorphisms underlying human variability Makes possible identification of genes predisposing to disease Understanding of defective genes in context of biological systems Circumvent limitations of defective genes Novel drugs Environmental controls Approaches such as stem-cell transplants or gene therapy Social, ethical, and legal issues Privacy of genetic information Limitations on genetic testing Patenting of DNA sequences Society’s view of older people Training of physicians Human genetic engineering Somatic gene therapy – inserting replacement genes Germ-line therapy – modifications of human germ line