Genomes are found in cells, the microscopic structures that make up all organisms. With a few exceptions, each of your body's trillions of cells contains a copy of your genome: the cells in your muscles, the cells in your brain, the cells in your blood, and so on.
Imagine all the trillions of genomes in your body, in other people's bodies, in cedar and apple trees, in walruses, forest mushrooms, and migrating birds: The whole world is full of genomes.
But if the genome is a commonplace thing, it is also quite powerful. A genome is information that affects every aspect of our behavior and physiology. Cooking dinner, digesting your food, talking, singing, sleepingyour genome has a hand in all these things.
A genome alone can't make a person, because we are also influenced by where we live, the human culture that surrounds us, and hundreds of other aspects of our environment. But the fact remains that you can't make a person without a genome.
Studying the human genome, therefore, is likely to give us insights into why some people die of heart disease and others die of cancer, why some people are comfortable schmoozing with a crowd of strangers and others are paralyzed by shyness, why some people have trouble keeping weight on while others have trouble keeping it off, and so on.
It's not difficult for scientists to get their hands on the human genome. They draw a bit of blood from people who volunteer to have their genomes studied, then use some simple laboratory procedures to break open the cells in the blood sample and extract the DNA. The body is constantly making more blood cells, so blood is a renewable genome resource.
Each human being contains a slightly different version of the human genome, but all human genomes are similar enough that we can learn about the human genome in general by studying the genomes of one or a few individual people.
Studying the genome can mean many different things. You can study a very small part of the genome or the genome as a whole. You can study the sequence of a gene, the function of a gene, the parts of the genome that regulate genes, or the DNA outside of genes. You can observe where genes are located in the genome, or investigate how different genes work together.
The next three chapters discuss several ways how scientists are studying the genome as a whole: sequencing genomes, mapping genomes, and studying the variation within genomes. Some of what we learn from this work might help doctors prevent and treat diseases better. Some of it might simply celebrate the variety that is the human species, or our unity with other forms of life. Some of it might open up possibilities we haven't even thought of yet.
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Updated on January 15, 2003