To prevent degradation and contamination, macromolecules such as proteins and RNA are inactivated using enzymes. Cells are broken open using a detergent solution containing buffering compounds. Most nucleic acid extraction techniques involve steps to break open the cell, and then the use of enzymatic reactions to destroy all undesired macromolecules. Various techniques are used to extract different types of DNA ( Figure 10.2). To study or manipulate nucleic acids, the DNA must first be extracted from cells. Messenger RNA (mRNA) is analyzed most frequently because it represents the protein-coding genes that are being expressed in the cell. Unlike DNA in eukaryotic cells, RNA molecules leave the nucleus. DNA has two complementary strands linked by hydrogen bonds between the paired bases. An entire set of DNA molecules in the nucleus of eukaryotic organisms is called the genome. The phosphate groups on these molecules each have a net negative charge. To understand the basic techniques used to work with nucleic acids, remember that nucleic acids are macromolecules made of nucleotides (a sugar, a phosphate, and a nitrogenous base). To accomplish the applications described above, biotechnologists must be able to extract, manipulate, and analyze nucleic acids. Biotechnology also has many industrial applications, such as fermentation, the treatment of oil spills, and the production of biofuels, as well as many household applications such as the use of enzymes in laundry detergent. The primary applications of this technology are in medicine (for the production of vaccines and antibiotics) and in agriculture (for the genetic modification of crops). Since the discovery of the structure of DNA in 1953, and particularly since the development of tools and methods to manipulate DNA in the 1970s, biotechnology has become synonymous with the manipulation of organisms’ DNA at the molecular level.
Biotechnology has been used for improving livestock and crops since the beginning of agriculture through selective breeding.