A genome is all of the DNA in a given organism. The DNA is split up into smaller groups of nucleotides called genes. Every gene contains the information for the production of a different protein. The human genome was once thought to have over 100,000 genes but it was recently found to have around 30,000 genes. The proteins produced by the genes determine different characteristics of the organism such as hair color, the ability to fight infection, some aspects of behavior, all enzymes, hormones, and almost all other characteristics of the organism.
Genes are passed down from generation to generation.
There is a two step process involved in order for the genes to be used. The first half of this process is called transcription. DNA is made up of four nucleotides: adenine, cytosine, guanine, and thiamin. These nucleotides are in pairs in the DNA and their order is very important because it dictates how the gene will be expressed. During transcription RNA, a similar molecule to DNA, comes in and makes the compliment copy of the DNA sequence.
The second half of this process is called translation. During translation the RNA is used to make amino acids, which are then used to make a protein. Not all of the RNA is used to make the amino acids, only the sections which are between the start and stop signals. Then sets of three nucleotides called codons are used to make specific amino acids. Different sets of amino acids code for different proteins.
So why is the genome so important? Because it is not only what determines many every day characteristics, it is also what determines genetic diseases that affect so many people.
Therefore increasing knowledge of the genome will give us more knowledge not only about these diseases but how to cure them. In 1990, a project called the U.S. Human Genome Project was launched in order to discover all the genes in human DNA as well as the sequences of the nucleotides that make up DNA. With this knowledge we hope to accomplish many things, one of which is gene therapy.
Gene therapy is a new approach to treating diseases by changing a persons genes.
Not only does gene therapy hope to be used to cure genetic diseases, but there are also promises of disease prevention. There are two types of gene therapy somatic and germline. Somatic gene therapy hopes to change the gene of the patient, but this change of expression in the gene will not be passed down to the next generation. Germline gene therapy is a modification of the cells that passes change on to the next generation. Most of the work being done at this time is on somatic gene therapy.
Another aspect to the discovery of the genome, which benefits gene therapy, is the ability to diagnose genetic illnesses.
For example Hemochromatosis is the most common genetic illness, and also very often goes undiagnosed. Until recently, in order to diagnose Hemochromatosis one had to have a liver biopsy. Now that scientists have managed to isolate the gene for Hemochromatosis they are able to spot it using probes, a process in which small pieces of DNA are used to help locate a gene on a chromosome. With similar processes they hope to also gain the ability to test for peoples reactions to various treatments, and to eventually have the ability to eliminate diseases before they come into existence.(Cowley, Geoffrey, 2000)
Recently in Current Science there was a report of the success that scientists at Johns Hopkins University had in the use of gene therapy to stop abnormal rhythms in pig hearts. The abnormal rhythms, cardiac arrhythmias are caused by either a defect in the pacemaker, cells which initiate heart muscle contraction, or by some sort of injury to the heart such as a heart attack.
Gene therapy was used by sending in a virus to carry copies of a gene, which blocks reactions that speed up heart rates, into one of the pacemakers. It was found that the pigs heart rates were 20 percent lower than that of the pigs who had not received gene therapy. This was a very important discovery because pigs hearts are the hearts most .