Gene amplification, also known as gene duplication or chromosomal duplication, is a cellular process in which multiple copies of a gene are produced. The result is an amplification of the phenotype, or expressed trait, associated with the gene. This usually occurs because of a serious genetic flaw in a cell or group of cells. Gene amplification has serious implications to evolutionary history as well as to drug resistance in cancer cells, and it is a major concern in biology for many additional reasons.
Most instances of gene amplification occur during an error in homologous recombination, when two similar strands of DNA exchange genetic information. This happens during many genetic processes, but is most prevalent in meiosis, by which sex cells are produced and replicated. Retrotransposons also contribute to gene duplication; they are genetic elements that are capable of amplifying themselves. The duplicated genes are prone to mutation, as mutations of the copied genes generally do not detract from the health of the host organism.
While its importance to evolution is debated, many believe that gene amplification is a tremendously important aspect of evolutionary history. Some evidence suggests that the entire yeast genome, the summation of all of yeast's genetic information, experienced a gene duplication event in relatively recent history. Plants tend to undergo gene amplification more commonly than animals do. Wheat, for example, is hexaploid, containing six complete copies of its genome. When genes are amplified and traits are strengthened, the strengthened traits are inherited by offspring and passed on to subsequent generations; this is a very significant consideration in evolution.
Not all gene amplification, however, has great significance to evolution. Sometimes, the amplified trait dies with the single organism that experiences the gene duplication. This occurs when a gene is overexpressed and the trait it codes for is expressed to a level that is unhealthy to the organism. It can also occur when the duplication occurs in a somatic cell rather than in a sex cell. The genetic information in somatic cells is not passed on to offspring, thus it does not present itself in later generations.
One of the most widely examined aspects of gene amplification is its role in drug resistance in some diseases. Cancer cells, for example, often express significant drug resistance because of amplification of the gene that prevents the cancerous cells from fully absorbing the chemotherapeutic drugs. Specifically, amplification occurs in a gene that codes for a protein that is able to selectively pump materials out of the cancerous cells. This protein tends to pump chemotherapeutic agents out of the cell, effectively neutralizing the treatment in many cases.
Because of its role in both health and science, gene amplification is considered by many to be a major concern to the field of biology. Further information regarding the topic could lead to major breakthroughs in the study of the origins of many species and of many traits that those species possess. It could also lead to a cure to a major disease that has claimed millions of lives: cancer.