Structural View of Biology
Biotechnology and Nanotechnology
Scientists are looking to nature for inspiration, and harnessing biological machinery for use in science and technology. Cells have evolved effective methods for performing a bewildering variety of nanoscale tasks. Many of these molecular machines may be used directly, by simply purifying the molecule and using it in the laboratory. Careful study of these molecular machines is also revealing the underlying nanoscale principles of their action, allowing researchers to create new molecular machines with novel functions.
Recombinant DNA Technology
The cell's genetic machinery may be harnessed to build custom proteins. Researchers use the cell's normal protein synthesis machinery to cut, splice and edit DNA, creating entirely new genes. This recombinant DNA may be added to cells and used to create the engineered proteins.
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Human cells (with a few unusual exceptions) each contain their own set of 46 long strands of DNA. All of our genetic information is encoded in these strands, with thousands of genes strung along their length. The ordering of genes, and the proximity of one next to the other, can be important for the proper usage of the information, so it is important that our cells protect their DNA from breakage. If one strand in the DNA breaks, it is not a disaster, but it can lead to problems when the DNA double helix is unwound during the processes of transcription and replication. Breakage of both strands, on the other hand, is far more serious. To protect us from these dangers, our cells use DNA ligases to glue together DNA strands that have been broken.
Bacteria are under constant attack by bacteriophages, like the bacteriophage phiX174 described in an earlier Molecule of the Month. To protect themselves, many types of bacteria have developed a method to chop up any foreign DNA, such as that of an attacking phage. These bacteria build an endonuclease--an enzyme that cuts DNA--which is allowed to circulate in the bacterial cytoplasm, waiting for phage DNA. The endonucleases are termed "restriction enzymes" because they restrict the infection of bacteriophages.
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