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What is a gene?
A gene is the fundamental physical and functional unit of heredity that is made up of tightly coiled threads or polymers of deoxyribonucleic acid (DNA). A DNA molecule consists of two strands that wrap around each other to resemble a twisted ladder or double helix. DNA is an informational molecule and is made up of four distinct nucleotides: deoxyadenosine (A), deoxyguanosine (G), deoxythymidine (T), and deoxycytidine (C). It is the nonrandom order of these individual "bases" that results in DNA being an informational molecule. However, in and of itself, DNA has no functional property. It is a chemical that, when placed in an appropriate environment, will direct the synthesis of particular and specific proteins, which make up the structural components of cells, tissues and enzymes (molecules that are essential for biochemical reactions). This environment is found within the cell. Organisms, from single-celled protozoans to far more complex human beings, are made up of cells containing DNA and associated protein molecules. The DNA is organized into structures called chromosomes, which encode all the information necessary for building and maintaining the organism. A DNA molecule may contain one or more genes, each of which is a specific sequence of nucleotide bases. It is the specific sequence of these bases that provides the exact genetic instructions that give an organism its unique traits.
Patented Genes
Isolated and purified genes are patentable inventions if they meet the PTO's standard criteria, including being novel, well described and useful.
Gene-based patents have helped attract the biotechnology and pharmaceutical industry's interest in the development of gene-based therapeutics. For example, the gene that encodes erythropoietin was cloned in 1985, which led to the production of recombinant EPO (Rhu-EPO). Amgen patented this gene in 1987. The protein expressed by this gene is used in the treatment of anemia arising from several diseases.
Introns, Exons and Genomes
A "genome" is the complete set of genetic instructions carried within a single cell of an organism. (A gene, in contrast, is a small subunit of the genome that in general "codes for"-that is, contains the information necessary for constructing-a single protein or protein subunit.) The human genome is estimated to comprise between 30,000 and 40,000 genes. Only about 3 percent of the human genome is known to include the protein-coding sequences (exons) of genes, and many genes are interrupted by sequences that have no coding function (introns). For a gene to be correctly made into a protein, these introns must be removed and the exons must be precisely spliced together.
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