The Thread of Life, is deoxyribonucleic acid, also known as DNA. Thismolecule which is the bases of life, is spiral shaped and found in the nucleusof cells. DNA has the genetic code for bodies, controls development ofembryos, and is able to repair damage caused to itself. All DNA moleculeshave linked units called nucleotides. These nucleotides have sub-units that have5 carbon sugars that are called deoxyribose.
DNA is composed of four basescalled adenine, thymine, guanine, and cytosine. These are some of the mainprinciples of DNA. What we know today about structure of DNA begins in 1868 whena Swiss biologist Friedrich Miescher did the first experiments on the nuclei ofcells. Miescher used the nuclei of pus cells from old medical bandages. In thesepus cells he found What We know today about structure of DNA begins in 1868 whena Swiss biologist Friedrich Miescher did the first experiments on the nuclei ofcells.
Miescher used the nuclei of pus cells from old medical bandages. In thesepus cells he found phosphorus with a substance he called nuclein. This nucleinhas an acidic portion which is classified as DNA. Another scientist Thomas HuntMorgan made an important discovery around 1900.
He observed that certaincharacteristics were inherited quickly through numerous generations of fruitflies. So he made the conclusion that these genes must be near one another onthe chromosome. In 1943 Oswald Avery, Colin MacLeod, and Maclyn McCarty, threescientists working in the Rockefeller institute, preformed an experiment bytaking DNA from a virulent (disease-causing) strain of Streptococcus pneumonaeand transformed a non-virulent (inactive) form back to a virulent form. Avery,MacLeod, and McCarty discovered from their experiments that DNA carried avirulent message that can be transferred into the recipient of non-virulentcells. This proved that DNA was a carrier of genetic information.
An importantdiscovery of the 1940s was the discovery by Erwin Chargaff who establishedthat hereditys alphabet which are the four bases adenine (A), guanine(G), thymine (T), and cytosine(C) can occur in different orders in differentorganisms. In 1953 James Watson and Francis Crick put forth a radical new ideaabout DNA. Their idea suggested that the DNA molecule was made up of two helicalchains instead of three intertwined chains as previously thought. Today we havea strong knowledge of DNA and scientists are applying that knowledge to a threebillion dollar project called the human genome project. This project willexamine the structure of human DNA and map out every single gene in the humanbody and will take 15 years.
The strong knowledge that we have of DNA allows thescientist to map out the genes at about 1 to 2 per day. This may not seem to bea very fast rate but scientists have already found the genes that cause diseasessuch as Hunningtons, Lou Gerhigs, and the Bubble-Boy disease. Another way that we use our strong knowledge of DNA is in criminalidentification. This plays a major role in todays society. Because eachpersons DNA is different (except in identical twins) police officers can takeblood or semen samples from a crime scene and take them to the lab foridentification.
This can insure the guilt or innocence of a suspect. An exampleof this is the O. J. Simpson case where investigators tried to match O. J.
s DNAto the DNA at the scene of the crime. Another way scientists apply theirknowledge of DNA today is by using special enzymes called restriction enzymesthat cut through the phosphate of DNA and these cut ends are called stickyends because they easily attract other tails from other DNA. Scientist usethese restriction enzymes for genetic engineering by removing a gene from oneorganism to another. In the future DNA has great possibilities for thebetterment of mankind and also the detriment.
The most obvious and controversialpossibility would be the cloning of humans. Scientists have already cloned sheepand other such organisms but have yet to take the step for cloning a human eventhough the technology is in place, the ethics of this may not be. The method toarrive at is quite simple. The embryo of an organism is removed in the earlydevelopment stage from the uterus then split and each separate part is placed ina surrogate uterus. Scientist are trying to clone organisms beyond the earlyembryonic stages, making for a much more difficult challenge. In 1996 Scottishscientists were able to clone a sheep, Dolly, by taking skin cells of a donorsheep and were deprived of nutrients to halt cell production.
Then anunfertilized egg is taken from another sheep with its nucleus removed, to eraseany genetic information and then finally fused with the skin cells from thefirst donor sheep. Though Dolly characteristics are the same as the sheep thatthe skin cells were taken from, she is not a 100% clone. She is not a true clonebecause not all organisms are found in the nucleus and therefore still retainsome of the traits from the surrogate sheep. The human Genome Project that issaid to be done by 2005 will sequence more 35 million pairs of human DNA. Because of such advanced technologies in the future and continually growingknowledge of DNA we may be able to find cures for such diseases as cancer orAIDS or even deformities such as sickle cell anemia or down syndrome. DNAtechnology is one of the leading sciences going into the 21st century.
Becauseit could potentially cure or eliminate such diseases or deformities as AIDS ordown syndrome it could also potentially harm us in the future with more lethalbiological weapons. However anything dealing with DNA is a highly complicatedand sensitive issue to most people. This knowledge is so powerful that we areable to play God, in a sense, and create or alter any organism we choose. Thatis why I believe that for the betterment of mankind we must regulate andrestrict this information to insure that it is used for ethical purposes ofmankind.Science
