What is a genome and why is it so important?


	Image: J.R. Paulsen, U.K. Laemmli, D.W. Fawcett, Visuals Unlimited Inc. DNA filaments from a chromosome.

A genome is all the genetic material contained in an organism, including its chromosomes, genes and DNA (deoxyribonucleic acid).

Genes carry information for making all the proteins needed by an organism to function. These proteins determine, among other things, an organism's appearance, health, and sometimes behaviour.

DNA is made up of four chemical bases (represented by A, T, C, and G) that may be repeated millions of times throughout a genome. The human genome, for example, has 3.4 billion pairs of bases.


•	What is a genome and why is it so important?
•	The human genome
•	How big is the human genome?
•	Genomics research

The word "genome" is a combination of "gene" and "chromosome".

The arrangement of these bases is extremely important, and determines the kind of an organism, whether a plant, animal or a fungus. It is the countless possible arrangements of these four bases that account for the huge diversity of life on Earth.

Researchers study not only the human genome, but also the genomes of all kinds of creatures, from microbes to animals like mice and pigs. The more we learn about other genomes, the more we may discover about our own.


	Contrasting DNA sequences.


	DNA strand segment showing bases.


	Image: J.R. Paulsen, U.K. Laemmli, D.W. Fawcett, Visuals Unlimited Inc. Chromosome.

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Last Update: 2008-08-12 © nature.ca Important Notices
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Image credits: 1) J.R. Paulsen, U.K. Laemmli, D.W. Fawcett, Visuals Unlimited, Inc.; 2) Harry Turner / National Research Council Canada; 3) The Geee! in Genome; 4) J.R. Paulsen, U.K. Laemmli, D.W. Fawcett, Visuals Unlimited, Inc.; 5) The Geee! in Genome.