Dna Helix Research Paper

helix because of the repulsion water molecules present in cells have on them. Each DNA has its proper structure because of some structures that can appear in the strand due to this high affinity between the bases. We can talk about the Harpin structures or the Cruciform structures. Harbin structures are little folds on one strand of DNA due to the bases associating with themselves and not with the opposite strand. Cruciform structures follow the same procedure but are symmetrical to both side (the 5’-> 3’ and the 3’->5’). N.E.R works by eliminating after the recognition of a different shape of DNA helix and will repair damages by a « cut and patch » type reaction. The global genome N.E.R (G.G-N.E.R) probes the genome for these distortions of

- 50% chance the child will receive one normal gene and one mutated gene, and will become a carrier of a HEXA mutation but won't develop the disease.
This types of genetic cross are often use to determine the recessivity or the dominance of alleles. It also enables to know the nature of chromosomes involved; if they are autosomal or gonosomal. The transmission of the disease also involves the randomness of the meiosis. For the persons carriers of the disease, we consider there is one chance on two to transmit the allele carrier of the illness but in fact there is a lot more complexity than a simply « split in two » of the DNA information. During the metaphase of the first meiosis the different homologous chromosomes are randomly attributed to a pole of the cell to be separate, lately in the anaphase of the first meiosis.
It is estimated that around 1 on 250 people are carriers of the HEXA mutation in the general population and among Jews of Sephardic origin. However, this value depend on the origin of the person. For example in the Ashkenazi Jew community (those chiefly from the Pale of

However nowadays, populations tend to be mixed, thanks to the society and mentality changes. Indeed, we can notice the different probability between the people of different communities to carry the disease. We can also establish that this mutation persist although the fact that Tay-Sachs disease induced an early death. All this process explain HEXA mutation does not spread extremely swiftly. In fact, Tay-Sachs disease is a lethal disease with far-reaching symptoms.
The life-expectancy is very low and the persons affected suffers from a multitude of troubles during the short time between when the disease is diagnosed and his death.
III- Symptoms and prevention.
The progressive deterioration of nerve cells leads to mental and physical inabilities. Most affected children have nerves damages when they are still in the womb, with symptoms beginning to appear between the 12th and 24th week of pregnancy. Progression is fast, and the child usually dies at the age of four or five. There are 3 forms of this disease, depending on the age of the first symptoms: the less active is the hexosaminidase, the younger the disease begins, and more the