DNA

DNA DNADeoxyribonucleic acid and ribonucleic acid are two chemical substances involved in transmitting geneticinformation from parent to offspring. It was known early into the 20th century that chromosomes, the geneticmaterial of cells, contained DNA. In 1944, Oswald T. Avery, Colin M. MacLeod, and Maclyn McCartyconcluded that DNA was the basic genetic component of chromosomes. Later, RNA would be proven toregulate protein synthesis. (Miller, 139)DNA is the genetic material found in most viruses and in all cellular organisms. Some viruses do not haveDNA, but contain RNA instead. Depending on the organism, most DNA is found within a single chromosomelike bacteria, or in several chromosomes like most other living things. (Heath, 110) DNA can also be foundoutside of chromosomes. It can be found in cell organelles such as plasmids in bacteria, also in chloroplasts inplants, and mitochondria in plants and animals.All DNA molecules contain a set of linked units called nucleotides.English: Cart oon representation of T7 RNA Polymera...Each nucleotide is composed of threethings. The first is a sugar called deoxyribose. Attached to one end of the sugar is a phosphate group, and atthe other is one of several nitrogenous bases. DNA contains four nitrogenous bases. The first two, adenine andguanine, are double-ringed purine compounds. The others, cytosine and thymine, are single-ringed pyrimidinecompounds. (Miller, 141) Four types of DNA nucleotides can be formed, depending on which nitrogenousbase is involved.The phosphate group of each nucleotide bonds with a carbon from the deoxyribose. This forms what is calleda polynucleotide chain. James D. Watson and Francis Crick proved that most DNA consists of twopolynucleotide chains that are twisted together into a coil, forming a double helix. Watson and Crick alsodiscovered that in a double helix, the pairing between bases of the two chains...