Genome

An organism's genome is the complete set of genetic instructions, passed from one generation to the next. The genome consists of a set of instructions for building each of the components of a living cell or virus. The information is found in nucleic acids: usually deoxyribonucleic acid ( DNA ), but sometimes ribonucleic acid (RNA).

Genetic information is organized into units called genes, each of which provides instructions to build one cellular component. Genes are parts of large strands of DNA called chromosomes. Much of what we know about human chromosomes comes from the Human Genome Project, begun in 1990. In February 2001 David Baltimore of the International Human Genome Sequencing Consortium and J. Craig Venter of Celera Genomics separately announced initial results on the complete sequencing of human DNA. More information about this project is available online. Scientists were able to determine the chemical code of chromosomes by applying recombinant DNA techniques, whereby millions of copies of human DNA were reproduced in bacteria, and polymerase chain reaction (PCR), which copies small sections of DNA for sequencing, to amplify a few strands of human DNA into more than a trillion strands, enough to detect in the sequencers. Enough DNA was produced to enable determination of the genetic code. Recombinant DNA also provides the basis for the construction of transgenic species such as Bt corn, which contains a gene from the bacteria Bacillus thuringiensis that ultimately helps to protect the corn plant from insects. The terms "biotechnology" and "genomics" are used to describe the application of these new techniques and new genetic information to produce new products. Examples of new biotech products include medical products such as cloned human insulin, human growth factor, and human clotting factors. These products are used to treat diseases caused by genetic errors. The new cloned materials are cheaper and safer than animal substitutes or isolated human materials. Another new biotech product is the herbicide-resistant soybean. These plants allow farmers to kill weeds in fields already planted with soybeans, without affecting the growth of soybeans.

SEE ALSO Agricultural Chemistry ; Chromosome ; Genes ; Nucleic Acids ; Polymerase Chain Reaction (PCR) ; Recombinant DNA .

David Speckhard

Bibliography

Felsenfeld, Gary (1985). "DNA." Scientific American 253(4):58–67.

International Human Genome Sequencing Consortium (2001). "Initial Sequencing and Analysis of the Human Genome." Nature 409:860–921.

Venter, J. Craig, et al. (2001). "The Sequence of the Human Genome." Science 291: 1304–1351.

Weinberg, Robert (1985). "The Molecules of Life." Scientific American 253(4):48–57.

Internet Resources

Human Genome Project. More information is available from http://www.nhgri.nih.gov/HGP/ .