A Brief History (Genetics & Inherited Conditions)
In 1871, Swiss physician Johann Friedrich Miescher reported that the chief constituent of the cell nucleus was nucleoprotein, or nuclein. Later it was established that the nuclei of bacteria contained little or no protein, so the hereditary material was named nucleic acid. At the end of the nineteenth century, German biochemist Albrecht Kossel identified the four nitrogenous bases: the purines adenine (A) and guanine (G) and the pyrimidines cytosine (C) and uracil (U). In the 1920’s, Phoebus A. Levene and others indicated the existence of two kinds of nucleic acid: ribonucleic acid (RNA) and deoxyribonucleic acid (DNA); the latter contains thymine (T) instead of uracil.
The chemical identity of genes began to unfold in 1928, when Frederick Griffith discovered the phenomenon of genetic transformation. Oswald Avery, Colin MacLeod, and Maclyn McCarty (in 1944) and Alfred Hershey and Martha Chase (in 1952) demonstrated that DNA was the hereditary material. Following the elucidation of the structure of DNA in 1953 by James Watson and Francis Crick, pioneering efforts by several scientists led to the eventual synthesis of a gene. The successful enzymatic synthesis of DNA in vitro (in the test tube) in 1956, by Arthur Kornberg and colleagues, and that of RNA by Marianne Grunberg-Manago and Severo Ochoa, also contributed to the development of synthetic genes. In 1961, Marshall Nirenberg and Heinrich Matthaei synthesized...
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Gene Synthesis (Genetics & Inherited Conditions)
Protein engineering is possible by making targeted changes in a DNA sequence to produce a different product (protein) polypeptide with different properties, such as stress tolerance. The process of targeting a specific change in the nucleotide sequence (site-directed mutagenesis) allows the correlation of gene structure with protein function. Rapid sequencing with modern capillary DNA sequencers facilitates determination of the order of nucleotides that make up a gene in a matter of hours.
Once the sequence of a gene is known, it can be synthesized from nucleotides using gene machines. A gene machine is simply a chemical synthesizer made up of tubes, valves, and pumps that bonds nucleotides together in the right order under the direction of a computer. An intelligent person with a minimum of training can produce synthetic genes. A gene may be isolated from an organism using restriction enzymes (any of the several enzymes found in bacteria that serve to chop up the DNA of invading viruses), or it may be made on a gene machine. For example, the chymosin gene (an enzyme used in cheese making) in calves can be synthesized from its known nucleotide sequence instead of isolating it from calf DNA using restriction enzymes. Alternatively, chymosin mRNA can be obtained from calf stomach cells, which can be transformed into DNA through reverse transcription.
New or modified genes may be manufactured to obtain a desired product....
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Further Reading (Genetics & Inherited Conditions)
Aldridge, Susan. The Thread of Life: The Story of Genes and Genetic Engineering. New York: Cambridge University Press, 1996. Provides a guide to DNA and genetic engineering.
Carlson, Robert. Biology Is Technology: The Promise, Peril, and New Business of Engineering Life. Cambridge, Mass.: Harvard University Press, 2009. Describes how new mathematical, computational, and laboratory tools can facilitate the engineering of biological artifacts, including organisms and ecosystems. Questions to what end these synthetic biology techniques should be used and who should be allowed to use them.
Gibson, Daniel G., et al. “Complete Chemical Synthesis, Assembly, and Cloning of a Mycoplasma genitalium Genome.” Science 319, no. 5867 (February 29, 2008): 1215-1220. Scientists at the Craig Venter Institute describe how they synthesized the complete genome for a small parasitic bacterium. They maintain their techniques can be used to construct large DNA molecules from chemically synthesized pieces or from combinations of natural and synthetic DNA.
Greber, David, and Martin Fussenegger. “Synthetic Gene Networks.” In Systems Biology and Synthetic Biology, edited by Pengcheng Fu and Sven Panke. Hoboken, N.J.: John Wiley and Sons, 2009. Discusses the characteristics of synthetic gene networks, the network building blocks, and the genetic transcriptional components of these...
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Web Sites of Interest (Genetics & Inherited Conditions)
Bio-Bricks Foundation. http://bbf.openwetware.org. The foundation registers and develops Bio-Bricks—standard biological parts for assembling DNA. Its Web site catalogs, explains, and discusses these biological parts.
Biobuilder.org. http://www.biobuilder.org. Provides animations and activities for teaching and learning about synthetic biology.
Synthetic Biology. http://syntheticbiology.org/FAQ.html. Frequently asked questions and answers that explain what synthetic biology is, why this field is useful, and the ethical and moral questions that it generates.
Synthetic Biology Project. http://www.synbioproject.org. A clearinghouse for information on synthetic biology, providing news and information about research, publications, and other aspects of the field.
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