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A World of Genomes

DNA strands leading to various animalsWhat do a fruit fly, a platypus, and a chickpea have in common? These are just a few of the organisms that have had their genomes sequenced and studied. Even before the Human Genome Project ended, genomic researchers started sequencing the genomes of a wide variety of organisms. Genome sequencing has helped scientists understand pets such as dogs and cats; agricultural animals like cows and pigs; crop plants such as rice, corn, barley; and a host of other living things. The list of organisms that have been totally or partially sequenced continues to grow: As of April 2013, whole genome sequences have been generated for 112 vertebrates, along with 455 non-vertebrates and nearly 9,000, mostly harmful, bacteria.

You may wonder: “Why have we generated genome sequence data from so many species?” One reason is that having a more complete genomic picture of various living things around us helps us to better comprehend how we fit into this world. Using genomic technologies, we can study evolution's notebook at a finer level of detail and reach a clearer understanding of the experiments carried out over evolutionary time. We can track a genetic function from one species to the next, from microbes right up to humans. We can see which parts of our genome we share with other organisms and how genes change through time while maintaining the biological functions essential for survival.

The bits of DNA sequences that have remained conserved throughout evolution are also a little surprising. For example, only about 2 percent of our genome provides instructions for building the proteins that keep cells functioning. Put a different way, protein-coding sequences altogether make up a modest 20,000 genes in humans. This was an early lesson in genomic humility. Before the Human Genome Project, we thought that the human genome contained close to 100,000 genes!

Photo Credits

Illustration courtesy of Darryl Leja, NHGRI