The Human Genome Project has issued multiple announcements about "finishing" the sequence, with landmark advances announced in 2003 and in 2006. Both of these followed a joint announcement by public (National Institutes of Health) and private (Celera) organizations that they had working drafts of a human genome in 2000. In reality, however, the complete sequencing of the human genome is still not complete because current technology has left several million bases of repeat-rich heterochromatin and many small gaps unfinished Brief guide to DNA sequencing.
To better understand why this is the case, think of the human genome as an encyclopedic reading of our DNA sequence in 23 volumes. Within these volumes, there are portions of the text that differ from person to person (variability) and there are long, repetitive stretches of apparent gibberish (chapters worth of CACACA, for example) Brief guide to DNA sequencing. The first of these issues highlights the fact that the human genome is not a singular edition—in other words, every person on Earth has a unique genome sequence. This variability, along with the repeats within the sequence, make it difficult for computers to assemble genomes—it's a bit like putting a together puzzle with identically shaped pieces.
Thus, sequencing technologies both old and new have brought us information about many genomes, and they continue to tell us which genes are being expressed and by how much. New pyrosequencing methods have drastically cut the cost of sequencing and may eventually allow every person the possibility of personalized genome information. Being able to read how our genes are expressed offers the promise of advanced medical treatments, but it will certainly require considerable work to generate, understand, organize, and apply this massive amount of data to human disease.
The recent publication of a draft of the platypus genome (Warren et al., 2008) has garnered a great deal of newspaper coverage, much of which has been misleading. Over and over again, the article lead is that the platypus is "weird" or "odd," or even worse, that the animal is a chimera. One author, for instance, describes the platypus as a "genetic potpourri—part bird, part reptile, and part lactating mammal" (AFP, 2008). Unfortunately, such statements are inaccurate. In reality, the platypus is not part bird, as birds are an independent and (directly) unrelated lineage. Moreover, although one could say that the platypus is part reptile, it is so only in the sense that it is a member of the great reptilian clade that also includes prototherians, marsupials, birds, lizards, snakes, dinosaurs, and eutherian mammals (including humans). Using this line of reasoning, we humans could say with equal justification that we, too, are part reptileand Brief guide to DNA sequencing.
To better understand why this is the case, think of the human genome as an encyclopedic reading of our DNA sequence in 23 volumes. Within these volumes, there are portions of the text that differ from person to person (variability) and there are long, repetitive stretches of apparent gibberish (chapters worth of CACACA, for example) Brief guide to DNA sequencing. The first of these issues highlights the fact that the human genome is not a singular edition—in other words, every person on Earth has a unique genome sequence. This variability, along with the repeats within the sequence, make it difficult for computers to assemble genomes—it's a bit like putting a together puzzle with identically shaped pieces.
Thus, sequencing technologies both old and new have brought us information about many genomes, and they continue to tell us which genes are being expressed and by how much. New pyrosequencing methods have drastically cut the cost of sequencing and may eventually allow every person the possibility of personalized genome information. Being able to read how our genes are expressed offers the promise of advanced medical treatments, but it will certainly require considerable work to generate, understand, organize, and apply this massive amount of data to human disease.
The recent publication of a draft of the platypus genome (Warren et al., 2008) has garnered a great deal of newspaper coverage, much of which has been misleading. Over and over again, the article lead is that the platypus is "weird" or "odd," or even worse, that the animal is a chimera. One author, for instance, describes the platypus as a "genetic potpourri—part bird, part reptile, and part lactating mammal" (AFP, 2008). Unfortunately, such statements are inaccurate. In reality, the platypus is not part bird, as birds are an independent and (directly) unrelated lineage. Moreover, although one could say that the platypus is part reptile, it is so only in the sense that it is a member of the great reptilian clade that also includes prototherians, marsupials, birds, lizards, snakes, dinosaurs, and eutherian mammals (including humans). Using this line of reasoning, we humans could say with equal justification that we, too, are part reptileand Brief guide to DNA sequencing.
