DNA
Deoxyribonucleic acid and ribonucleic acid are two chemical substances involved in transmitting genetic information from parent to offspring. It was known early into the 20th century that chromosomes, the genetic material of cells, contained DNA. In 1944, Oswald T. Avery, Colin M. MacLeod, and Maclyn McCarty concluded that DNA was the basic genetic component of chromosomes. Later, RNA would be proven to regulate 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 chromosome like bacteria, or in several chromoso ...view middle of the document...
This is known as base pairing. (Miller, 143)The DNA of an organism provides two main functions. The first function is to provide for protein synthesis, allowing growth and development of the organism. The second function is to give all of it's descendants it's own protein-synthesizing information by replicating itself and providing each offspring with a copy. The information within the bases of DNA is called the genetic code. This specifies the sequence of amino acids in a protein. (Grolier Encyclopedia, 1992) DNA does not act directly in the process of protein synthesis because it does not leave the nucleus, so a special ribonucleic acid is used as a messenger (mRNA). The mRNA carries the genetic information from the DNA in the nucleus out to the ribosomes in the cytoplasm during transcription.(Miller, 76)This leads to the topic of replication. When DNA replicates, the two strands of the double helix separate from one another. While the strands separate, each nitrogenous base on each strand attracts it's own complement, which as mentioned earlier, attaches with hydrogen bonds. As the bases are bonded an enzyme called DNA polymerase combines the phosphate of one nucleotide to the deoxyribose of the opposite nucleotide.This forms a new polynucleotide chain. The new DNA strand stays attached to the old one through thehydrogen bonds, and together they form a new DNA double helix molecule. (Heath, 119) (Miller, 144-145)As mentioned before, DNA molecules are involved in a process called protein synthesis. Without RNA, thisprocess could not be completed. RNA is the genetic material of some viruses. RNA molecules are like DNA.They have a long chain of macromolecules made up of nucleotides. Each RNA nucleotide is also made up ofthree basic parts. There is a sugar called ribose, and at one end of the sugar is the phosphate group, and at theother end is one of several nitrogenous bases. There are four main nitrogenous bases found in RNA. There arethe double-ringed purine compounds adenine and guanine, and there is the single-ringed pyrimidinecompounds of uracil and cytosine. (Miller, 146)RNA replication is much like that of DNA's. In RNA synthesis, the molecule being copied is one of the twostrands of a DNA molecule. So, the molecule being created is different from the molecule being copied. This isknown as transcription. Transcription can be described as a process where information is transferred fromDNA to RNA. All of this must happen so that messenger RNA can be created, the actual DNA cannot leavethe nucleus. (Grolier Encyclopedia, 1992)For transcription to take place, the RNA polymerase enzyme is needed first separate the two strands of thedouble helix, and then create an mRNA strand, the messenger. The newly formed mRNA will be a duplicateof one of the original two strands. This is assured through base pairing. (Miller, 147)When information is given from DNA to RNA, it comes coded. The origin of the code is directly related to theway the f...
