Friday, November 27, 2009

The discovery in 1953 of the structure of the molecule of DNA (deoxyribonucleic acid) by James Watson and Francis Crick gave rise to modern biotechnology as we know it today. In previous studies by Watson and Crick's discovery it was known that DNA stores genetic information (inheritance) in all living things. It was also known that DNA was formed by the combination of smaller molecules called nucleotides. The nucleotides in turn consist of a sugar (deoxyribose), a phosphate and one of the four following bases: adenine, guanine, cytosine and thymine or abbreviated A, G, C, T. Also it was known that, although the proportion of these nucleotides was different in each DNA molecule, provided the number of Aes was equal to the Tees and the number of Cs was equal to Ges.Watson and Crick, using these and other data, found that the DNA molecule consists of two long strands (each of them a chain of nucleotides) that are wound together resulting in a double helix like a spiral staircase . The side or "railing" of the ladder is made up of sugars (deoxyribose) and phosphates and the rungs are base pairs. In this structure, adenine always pairs with thymine (AT, TA) and cytosine pairs with guanine (CG, GC) and only allowed the pairings. The type of nucleotide and the sequence-order-known that these molecules are arranged is the way genetic information is written using a kind of alphabet of 4 letters.The DNA molecule has the ability to unfold and may serve as a template to give rise to another identical molecule, and this is how genetic information passes from father to son. The key lies in how this occurs in the complementarity of the bases adenine makes the match only with thymine and cytosine only with guanine. In general, a cell has a very sophisticated machinery that allows for very accurate copies of the DNA molecule, whether there are different repair systems. However, sometimes there are failures. When this happens it is said that there has been a mutation (ie, a genetic error) and if it can become sufficiently important to change information that carried the DNA molecule.The chromosomes and genesIf all the DNA in the nucleus of human cells should be found stretched would measure up to 1.8 meters, or about 300,000 times more than the core diameter. To avoid this problem, DNA is highly folded to form structures called chromosomes. The human genome consists of 23 pairs of chromosomes. Each chromosome is a single molecule of DNA which in turn is composed of thousands of nucleotides. If written in the alphabet of 4 letters all the genetic information that contains a human cell would fill a book with more than 500,000 pages. Therefore, the three characteristics that allow the DNA molecule to be the repository of genetic information of an organism are that the DNA molecule contains information based on the order and composition of the nucleotides that form, that is capable of pass this information from generation to generation because each string can serve as a template to manufacture its complement, and that is flexible, allowing you to store all the information required to be a living being is and perform their duties in a space as small as intracellularly.9. ProteinsIn a single chromosome, and therefore a single DNA molecule, many genes are aligned. In general, the gene is called DNA fragment that carries the information to synthesize a protein. It is important to note that although the DNA that stores genetic information of an organism, proteins are running such information and which are molecules essential for all aspects of structure and cell activity. There are many different proteins (eg hemoglobin, keratin hair and nails, collagen, hormones such as insulin, antibodies, enzymes, etc.), but they are all formed by the combination of only 20 types of molecules more Small called amino acids. As in the case of DNA, is the sequence in which amino acids are arranged such that unlike other protein but only by the fact that the specific amino acid sequence of a protein is conferred by the forms it takes in space and that is absolutely basic to its function. When a protein loses its native form is said to be denatured and the denaturation usually involves a loss of protein activity.Messenger RNAAlthough every cell of an organism have the information necessary for all bodily functions, each cell type is specialized to perform a particular function. So skin cells perform different functions that the liver cells. The difference lies in the type of proteins present and necessary in each cell. Therefore, each cell type is characterized by generating, ie express, only some of the genes in their genomes available. When a cell needs a protein should go get the information to produce it in their DNA. In the case of eukaryotic cells, DNA is found in the cell nucleus, however proteins are produced in another part of the cell called the cytoplasm