DNA :: Deoxyribonucleic Acid essays research papers

deoxyribonucleic acetousDNA, or Deoxyribonucleic Acid, is described, in Encarta cyclopedia as a genetic material of all cellular organisms and nigh viruses. DNA carries the information needed to direct protein synthesis and replication. Protein synthesis is the work of the proteins needed by the cell or virus for its activities and development. Replication is the work by which DNA copies itself for each(prenominal) descendant cell or virus, qualifying on the information needed for protein synthesis. In most cellular organisms, DNA is organized on chromosomes located in the nucleus of the cell.A mote of DNA consists of two chains, strands composed of a large number of nucleotides, that atomic number 18 linked together to form a chain. These chains look like a twisted ladder and argon called a double helix. for each one nucleotide consists of triple units sugar molecules called deoxyribose, a phosphate base, and one of iv different nitrogen containing compounds, also call ed bases. The four are adenine (A), gravitational constant (G), thymine (T), and cytosine (C). The deoxyribose molecule occupies the center of the nucleotide, with the phosphate group on one side and a base on the other(a). The phosphate group of each nucleotide is also linked to the deoxyribose of the adjacent nucleotide in the chain. These linked deoxyribose-phosphate subunits form the side rails of the ladder. The bases face inward toward each other, forming the steps of the ladder.The nucleotides in one DNA strand have a specific association with the corresponding nucleotides in the other DNA strand. Because of the chemical affinity of the bases, nucleotides containing adenine are always paired with nucleotides containing thymine, and nucleotides containing cytosine are always paired with nucleotides containing guanine. The complementary bases are joined to each other by weak chemical bonds called hydrogen bonds.DNA carries the instructions for the toil of proteins. A protei n is composed of smaller molecules called amino acids, and the structure and function of the protein is obdurate by the sequence of its amino acids. The sequence of amino acids, in turn, is find by the sequence of nucleotide bases in the DNA. A sequence of three nucleotide bases, called a triplet, is the genetic code word, or codon, that specifies a accompaniment amino acid. For instance, the triplet GAC (guanine, adenine, and cytosine) is the codon for the amino acid leucine, and the triplet CAG (cytosine, adenine, and guanine) is the codon for the amino acid valine.