Chemistry Research Paper - Vitamin B12 Example | Topics and Well Written Essays - 1000 words

Chemistry - Vitamin B12 - Research Paper Example The cobalt ? position, which is the region below the corrin ring plane, may either be open or could be occupied by a side chain of a heterocyclic nitrogen or the solvent (Combs 55). Methyl, nitro, aqua, sulfato, sulfito, hydroxo, 5-deoxyadenosyl, Br-, CN- or a Cl- group may occupy the cobalt ? position, which is the region above the corrin ring plane (Combs 55). The molecule is an octahedral complex, which apart from the corrin ring, also contains a nucleotide along with another cobalt bound group. The corrin ring is formed of four pyrrole rings, three of which are linked with methylene bridges and one with a direct bond. The cobalt atom (Co3+) at the center of the corrin ring is triply ionized and is bound to the nitrogen atoms of the four pyrrole rings (Combs 56). Chemistry Removal of the central cobalt atom of the molecule results in loss of biological activity. Like all corrinoids, vitamin B12 is a crystalline substance with absorption spectra above 300 nm due to ?-? transitions in the corrin ring (Combs 56). It is yellow, red or red-orange in color, is soluble in water, fairly heat stable, and decomposes above 210Â °C (Combs 57). ... Functions and Mechanism Vitamin B12 has a key role in the metabolism of folate in the human body (Insel et al. 452). It transfers a methyl group from the folate coenzyme Tetrahydrofolic acid (THFA) converting THFA to its methylene form. In absence of the vitamin, THFA cannot transform into its methylene form, which is its active form that is involved in many metabolic pathways (Insel et al. 452). As THFA is involved in folate metabolism, deficiency of vitamin B12 results in the deficiency of folate because of absence of active form of THFA. Therefore, vitamin B12 deficiency amounts to folate deficiency, which in turn leads to megaloblastic anemia. Several enzymes that convert homocysteine to methionine are also dependant on vitamin B12 and THFA. Conversion of homocysteine to methionine reduces the levels of homocysteine in the blood, thereby lowering the risk of heart diseases. This mechanism is affected in case of vitamin B12 deficiency (Insel et al. 453). Vitamin B12 also functions in the maintenance of the myelin sheath, which is a protective coat surrounding nerve fibres (Insel et al. 453). Moreover, some fatty acid chains require rearrangement of their carbon atoms in order to enter the citric acid cycle. This function is also performed by vitamin B12 (Insel et al. 453). Vitamin B12 is stored in the liver and can last for about 2 years, while the symptoms of its deficiency may not be apparent for up to almost 12 years (Insel et al. 454). Anemia is the major outcome of vitamin B12 deficiency. In absence of vitamin B12 and in turn, folate, megaloblasts are formed instead of red blood cells, leading to megaloblastic anemia. Vitamin B12 deficiency also results in cognitive defects by causing

Ethical Issues Of Euthanasia Essay Example | Topics and Well Written Essays - 1750 words

Ethical Issues Of Euthanasia - Essay Example In this modern world, despite the progress that has been made both in science and technology and in particular in the regulations and law field, there is still a lot of controversy and ambiguity over the notion of euthanasia ( the peaceful death). Therefore, this ethical dilemma may impose the legal and ethical risk on health care providers. The legal and ethical aspects of the notion of euthanasia are commonly debated in many countries. Several opinions are offered which are based on the principles of religious beliefs and personal morality. Hence, researchers and scientists are still trying to reach a general consensus on this dilemma that is ethical in nature (Somerville, 2001).In countries that practice the Islamic faith, there are debates and discussions on withdrawing or withholding the life support therapies or giving a patient at the end of life the freedom to choose peaceful death. Healthcare providers have no protection or immunity if they decide to help a patient die based on the Islamic law. Therefore, from the point of view of Islam, a patient has no right to die voluntarily since life is an opportunity to refine the spirit and is a divine trust. Thus, nobody has the right to end a human life by interfering through active assistance (McDougall et al., 2008).Therefore, withdrawing or withholding treatment of a patient is very difficult and can never be universal without considering the social, religious and cultural factors when it comes to decision making.