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Glossary Of Terms

antisense A piece of DNA that produces a mirror image (or antisense) mRNA that is opposite in sequence to the one that directs protein synthesis. The RNA will bind tightly to its mirror image, thus preventing the production of the particular protein.

C. elegans (Caenorhabditis elegans) A nematode worm that is relatively as primitive an organism as exists but shares many of the essential biological characteristics that comprise predominant concerns of human biology, making it an ideal laboratory research subject. It was used as the basis of study for the pioneering RNAi work of the Guo, S./Kemphues, K.J.and the Fire et al research teams.

comparative genomics The study of human genetics by comparisons with model organisms such as mice, the fruit fly, and the bacterium E. coli.

Dicer An enzyme in the RNase III family of dsRNA-specific ribonucleases that processes dsRNAs into siRNAs.

ddRNAi (DNA-directed RNA interference) A method for gene silencing in which a DNA segment is introduced into cells, triggering the production of dsRNA. The dsRNA is cleaved into siRNA, which destroys the target mRNA. Patented by Benitec Ltd. In March 1998.

DNA (deoxyribonucleic acid) The molecule that encodes genetic information. DNA is a double-stranded molecule held together by weak bonds between base pairs of nucleotides. The four nucleotides in DNA contain the bases adenine (A), guanine (G), cytosine (C), and thymine (T). In nature, base pairs form only between A and T and between G and C; thus the base sequence of each single strand can be deduced from that of its partner.

DNA bank A service that stores DNA extracted from blood samples or other human tissue.

DNA probe Single-stranded DNA or RNA molecules of specific base sequence, labeled either radioactively or immunologically, that are used to detect the complementary base sequence by hybridization

DNA sequence The relative order of base pairs, whether in a DNA fragment, gene, chromosome, or an entire genome.

double helix The twisted-ladder shape that two linear strands of DNA assume when complementary nucleotides on opposing strands bond together.

dsRNA (double-stranded RNA) RNA with two complementary strands; similar to DNA found in more complex cells. dsRNA has the ability to directly suppress and silence target genes, in that the process is founded on the basis that cells destroy RNA when it is double-stranded.

eiRNA (expressed interfering RNA) RNA used in an environment in which plasmid DNA coding for relevant dsRNA is inserted into targeted cells, allowing them to generate and convey specific dsRNA sequences that cleave into targeted gene silencing siRNAs.

fingerprinting In genetics, the identification of multiple specific alleles on a person's DNA to produce a unique identifier for that person.

forensics The use of DNA for identification. Some examples of DNA use are to establish paternity in child support cases; establish the presence of a suspect at a crime scene, and identify accident victims. gene A unit of hereditary material that forms a discrete component of the chromosome of most organisms encoding data in the form of a DNA sequence

gene amplification Repeated copying of a piece of DNA; a characteristic of tumor cells.

gene chip technology Development of cDNA microarrays from a large number of genes. Used to monitor and measure changes in gene expression for each gene represented on the chip.

gene expression The process by which a gene's coded information is converted into the structures present and operating in the cell. Expressed genes include those that are transcribed into mRNA and then translated into protein and those that are transcribed into RNA but not translated into protein (e.g., transfer and ribosomal RNAs).

gene mapping Determination of the relative positions of genes on a DNA molecule (chromosome or plasmid) and of the distance, in linkage units or physical units, between them.

gene pool All the variations of genes in a species.

gene prediction Predictions of possible genes made by a computer program based on how well a stretch of DNA sequence matches known gene sequences

gene product The biochemical material, either RNA or protein, resulting from expression of a gene. The amount of gene product is used to measure how active a gene is; abnormal amounts can be correlated with disease-causing alleles.

gene silencing The suppression or interruption of the expression of a gene at a transcriptional or translational level.

gene therapy An experimental procedure aimed at replacing, manipulating, or supplementing nonfunctional or abnormally functioning genes with healthy genes.

gene transfer Incorporation of new DNA into an organism's cells, usually by a vector such as a modified virus. Used in gene therapy.

genetic code The sequence of nucleotides, coded in triplets (codons) along the mRNA, that determines the sequence of amino acids in protein synthesis. A gene's DNA sequence can be used to predict the mRNA sequence, and the genetic code can in turn be used to predict the amino acid sequence.

genetic marker A gene or other identifiable portion of DNA whose inheritance can be followed.

genetic polymorphism Difference in DNA sequence among individuals, groups, or populations (e.g., genes for blue eyes versus brown eyes).

genetic predisposition Susceptibility to a genetic disease. May or may not result in actual development of the disease.

genetic screening Testing a group of people to identify individuals at high risk of having or passing on a specific genetic disorder.

genetic testing Analyzing an individual's genetic material to determine predisposition to a particular health condition or to confirm a diagnosis of genetic disease.

genetics The study of inheritance patterns of specific traits.

genome All the genetic material in the chromosomes of a particular organism; its size is generally given as its total number of base pairs.

genome project Research and technology-development effort aimed at mapping and sequencing the genome of human beings and certain model organisms.

genomic library A collection of clones made from a set of randomly generated overlapping DNA fragments that represent the entire genome of an organism.

genomics The study of genes and their function.

genotype The genetic constitution of an organism, as distinguished from its physical appearance (its phenotype).

IP (intellectual property) Intangible property that is the result of creativity, such as patents, trademarks and copyrights, and is allowed exclusive rights by intellectual property law over these intangibles on the equivalence of property rights, whether for a specified or indefinite period of time.

mRNA (messenger RNA) RNA that carries instructions from DNA to ribosomes for the synthesis of a protein.

NCBI RefSeq database (The National Center for Biotechnology Information Reference Sequence database) A repository, under the aegis of the National Institutes of Health, of comprehensive, integrated, non-redundant sets of predicted and annotated sequences, including genomic DNA, transcript (RNA), and protein products for major research organisms. The database serves as the standard for the basis for medical, functional, and diversity studies, and provides a reliable reference for gene identification and characterization, mutation analysis, expression studies, polymorphism discovery, and comparative analyses, and is used as a reagent for the functional annotation of genome sequencing projects, including those of human and mouse.

patent pool (as defined and referenced by the USPTO) An agreement between two or more patent owners to license one or more of their patents to one another or third parties. Alternatively, a patent pool may also be defined as "the aggregation of intellectual property rights that are the subject of cross-licensing, whether they are transferred directly by patentee to licensee or through some medium, such as a joint venture, set up specifically to administer the patent pool."

pharmacogenomics The study of the interaction of an individual's genetic makeup and response to a drug.

Polymerase chain reaction (PCR) A method for amplifying a DNA base sequence using a heat-stable polymerase and two 20-base primers, one complementary to the (+) strand at one end of the sequence to be amplified and one complementary to the (-) strand at the other end.


Any substance used in a chemical reaction, particularly as an element that is added to bring about the chemical change. Recombinant DNA technology Procedure used to join together DNA segments in a cell-free system (an environment outside a cell or organism).

ribozyme (RNA enzyme) An RNA molecule that can initiate the catalysis of a chemical reaction.

RISC (RNA-induced silencing complex) A nuclease complex, composed of proteins and siRNA, which targets and destroys endogenous mRNAs complementary to the siRNA within the complex.

RNA (ribonucleic acid) A nucleic acid comprised of a string of covalently bonded (formed by shared non-ionic electrons) nucleotides, and differentiated from DNA by the presence of an auxiliary hydroxyl group that is appended to each pentose ring, as well as by the use of uracil rather than thymine. RNA transcriptionally conveys the genetic information from DNA into proteins.

RNAi (RNA interference) A mechanism in which the presence of small fragments of dsRNA, with a sequence matching a given gene, interferes with the expression of that gene but does not appear to interact with the DNA; post-transcriptional gene silencing (PTGS) caused by the introduction of double-stranded RNA (dsRNA). The process occurs when long dsRNAs are cleaved by the enzyme Dicer in siRNAs, which are then recruited to an RNA-induced silencing complex which mediates the cleavage of the target mRNA. Andrew Fire and Craig Mello coined the name in 1998, when injecting dsRNA into C. elegans.

shRNA (short hairpin RNA) A short sequence of RNA that makes a tight hairpin turn and can be in sequence-specific gene silencing in mammalian cells.

single nucleotide polymorphism (SNP) DNA sequence variations that occur when a single nucleotide (A, T, C, or G) in the genome sequence is altered.

siRNA (small interfering RNA) Also called "guide RNAs," these 20-25 nucleotide-long dsRNAs can induce post-transcriptional gene silencing when introduced in cells.

theranostics the development of diagnostic tests that can identify which patients are most suited for a drug and provide feedback on how well the drug is working

USPTO (United States Patent and Trademark Office) An agency of the United States Department of Commerce which promotes the progress of science and the useful arts by giving inventors the exclusive right to their respective discoveries for limited periods of time. Its primary services are processing patent and trademark applications and disseminating patent and trademark information. www.uspto.gov.