Genetic Advances
6. Human Genome Project
Human Genome Project
A person’s genome is all of his or her genetic information; in other words, the human genome is all the information that makes us human. The Human Genome Project (Figure below) was an international effort to sequence all 3 billion bases that make up our DNA and to identify within this code the over 20,000 human genes. Scientists also completed a chromosome map, identifying where the genes are located on each of the chromosomes. The Human Genome Project was completed in 2003. Though the Human Genome Project is finished, analysis of the data will continue for many years.
To complete the Human Genome Project, all 23 pairs of chromosomes in the human body were sequenced. Each chromosome contains thousands of genes. This is a karyotype, a visual representation of an individuals chromosomes lined up by size.
There are many exciting applications of the Human Genome Project. The genetic basis for many diseases can be more easily determined, and now there are tests for over 1,000 genetic disorders. The National Institutes of Health, the United States government’s premiere biomedical research community, is also looking for ways to reduce the costs of sequencing so that people can have a map of their individual genome. Although some disorders are caused by a single gene, many other illnesses are caused by a combination of several genes and a person’s lifestyle. Analysis of your own genome could determine if you are at risk for specific diseases. Knowing you might be genetically prone to a certain disease would allow you to better seek preventive lifestyle changes and medical screenings.
A genetic map shows the location (or loci) of a gene on a chromosome. Genetic maps are important tools to help researchers understand genes and genetic diseases. Knowing where genes are in relation to other genes and knowing the order of genes on a chromosome is an important aspect of human genetics. The frequency of recombination (crossing-over during prophase I of meiosis) allows geneticists to estimate the distance between loci. Because crossing-over occurs relatively rarely at any location along the chromosome, the frequency of recombination between two locations depends on their distance. The farther apart genes are on the same chromosome, the more likely there is to be a cross-over event between them. The likelihood of a cross-over event between two closely located genes (said to be linked) is small.
CK-12 Foundation, Biology. http://creativecommons.org/licenses/by-nc-sa/3.0/