Genetics

More than any other biological discipline, genetics is responsible for the most dramatic breakthroughs in biology and medicine today. Scientists are rapidly advancing in their ability to engineer genetic material to achieve specific characteristics in plants and animals. The primary way to genetically engineer DNA is called gene cloning, in which a segment of one DNA molecule is removed and then inserted, into another DNA molecule. This process takes advantage of restriction enzymes to cut DNA into fragments of different lengths and ligase to re-create new molecules. Restriction enzymes act as molecular scissors, cutting larger molecules (like DNA) at specific sites. The ends of these fragments are "sticky" in that they have an affinity for complimentary ends of other DNA fragments. DNA ligase acts as a glue to join the ends of the two molecules together. This approach has applications in agriculture and medicine.

In agriculture, genetic engineering is used to produce transgenic animals or plants, in which genes are transferred from one organism to another. This approach has been used to reduce the amount of fat in cattle raised for meat, or to increase proteins in the milk of dairy cattle that favor cheese making. Fruits and vegetables have also been genetically engineered so they do not bruise as easily, or so they have a longer shelf life. On the other hand, in medicine, genetic engineering provided great advancements in production of antibiotics, hormones, vaccines, understanding disease mechanisms and in therapy. Gene therapy is currently being developed and used as it provides the opportunity to introduce specific genes into the body to either correct a genetic defect or to enhance the body's capabilities to fight off disease and repair itself. Because many inherited or genetic diseases are caused by the lack of an enzyme or protein, scientists hope to one day treat the unborn by inserting genes to provide the missing enzyme.

Genetic fingerprinting (DNA typing) is based on each individual's unique genetic code. To identify parentage, diagnose inherited diseases in prenatal laboratories or the presence of someone at a crime, scientists use molecular biology techniques such as DNA fingerprinting by applying restriction fragment length polymorphisms (RFLPs) analysis (identifying the characteristic patterns in DNA cut with the restriction enzymes), microsattelite analysis (looking at the small specific DNA sequences), DNA hybridization, DNA sequencing or polymerase chain reaction (PCR). Development of PCR allows to analyse small amounts of DNA acquired from hair, semen, blood, fingernail fragments, or fetal cells by utilizing DNA polymerase enzyme (the same enzyme used naturally by cells in mitosis) to create identical copies of a DNA molecules from small samples.

One of the most exciting recent developments in genetics is the initiation of the Human Genome Project (HGP). This project is designed to provide a complete genetic road map outlining the location and function of the 100,000 or so genes found in human cells encoded in over three billion bases. The first human genome draft sequences were published in February 2001 by the Celera company and the HGP consortium in the journals Science and Nature, respectively. As a result, genetic researchers will have easy access to specific genes to study how the human body works and to develop therapies for diseases. Gene maps for other species of animals are also being developed.