Biology World

The basic definition of evolution is a change in the gene pool of a population of organisms over time. All of evolution is based on genetic change. Scientists still have a lot to learn about the workings of genetic code, but science has built up a large volume of knowledge about how the genetic material of living organisms works. We have a pretty good understanding of what DNA does in general and, equally important to evolution, how DNA changes.  

The foundation of evolution is not just working DNA but changing DNA. The primary mechanism of significant change in DNA is mutation. That DNA is subject to mutation is a fact and it has been directly observed. In addition, many of the mechanisms of mutation are understood including mutations that can lead to drastic changes in an organism. This means we understand some of the mechanisms by which changes in an organism can be affected.


Genetic engineeringrecombinant DNA technologygenetic modification/manipulation (GM) and gene splicing are terms that apply to the direct manipulation of an organism's genes. Genetic engineering is different from traditional breeding, where the organism's genes are manipulated indirectly. Genetic engineering uses the techniques of molecular cloning and transformation to alter the structure and characteristics of genes directly. Genetic engineering techniques have found some successes in numerous applications. Some examples are in improving crop technology, the manufacture of synthetic human insulin through the use of modified bacteria, the manufacture of erythropoietin in hamster ovarycells, and the production of new types of experimental mice such as the oncomouse (cancer mouse) for research.

 Genes alone cannot account for what a person is, but even the slightest distinguishing traits between people can be attributed to individual genes. James Randerson reports Genetics is rarely all or nothing. In almost every case your version of a gene will give you an increased or a lowered chance of a particular outcome (like becoming obese) but that outcome is not certain. Your other genes and environmental influences, such as how much you eat and exercise, all work together to determine how you end up.

The two most important mechanisms of evolution are natural selection and genetic drift. Most people have a reasonable understanding of natural selection but they don't realize that drift is also important. The anti- evolutionists, in particular, concentrate their attack on natural selection not realizing that there is much more to evolution. Darwin didn't know about genetic drift, this is one of the reasons why modern evolutionary biologists are no longer "Darwinists"


A genetic disorder is a disease caused by a different form of a gene called a variation, or an alteration of a gene called a mutation. Many diseases have a genetic aspect. Some, including many cancers, are caused by a mutation in a gene or group of genes in a person's cells. These mutations can occur randomly or because of an environmental exposure such as cigarette smoke.

Other genetic disorders are inherited. A mutated gene is passed down through a family and each generation of children can inherit the gene that causes the disease. Still other genetic disorders are due to problems with the number of packages of genes called chromosomes. In Down syndrome, for example, there is an extra copy of chromosome 21.


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