P53 mutations and Cancer Essay Example | Topics and Well Written Essays - 1000 words

P53 mutations and Cancer - Essay Example The genes are codes that instruct the cell how to make many different proteins. One gene 'codes' for one protein. In a cancerous cell some of the genes have been damaged or lost. And this is termed as 'mutation'. A mutation may mean that too much protein is madeor that a protein is not made at all. There are three different types of genes that are important in making a cell cancerous genes that encourage the cell to multiply; genes that stop the cell multiplying; and genes that repair the other damaged genes. Some genes encourage multiplication of cells. In general these genes are only activated during repair after a wound or an operation in an adult. But if these genes become abnormal, they instruct the cell to multiply all the time and are termed as oncogenes or in other words are the 'cancer genes'. There are also those genes that instruct the cells to stop multiplication and these are the tumor suppressor genes. These are genes are in the cell particularly to stop the cell multiplying or doubling. They act as the natural brake to the oncogene's accelerator. Here again the problem is accelerated if one of these 'tumor suppressor genes' becomes damaged and stops working. As a result the cell may then carry on multiplying. In other words it becomes immortal, which is one of the properties of a cancer cell. The best known tumor suppressor gene is called p53. ... Disruption of this gene is associated with approximately 50 to 55 percent of human cancers. In other words it can be said that the p53 protein acts as a checkpoint in the cell cycle, either inhibiting or initiating programmed cell death. Hence p53's has an important role to play when in comes to cancer which is nothing but unchecked proliferation of cells. At this point of time there is another question that arises in our mind. If people have a built-in tumor suppressor then why do so many get cancer Research suggests that there are several factors that determine the p53 molecule activity as it can be inactivated in several ways. Genetics plays an important role, for instance, in some human families if p53 mutations are inherited the family members have a high incidence of cancer. However in many cases the molecule is inactivated by an external source. For instance, DNA tumor viruses, such as the human adenovirus and the human papilloma virus, have a tendency to bind to and inactivate the p53 protein function, which invariably alter cells and initiate tumor growth. Besides, some sarcomas amplify another gene, called mdm-2, which produces a protein that binds to p53 and inactivates it, much the way the DNA tumor viruses do (Burley n. pag). Hence it can be said that there are several factors that determine the functioning of p53 molecule s. There is another way in which p53 molecule can trigger the cancerous growth in human body. In a normal cell, p53 protein binds DNA, which in turn stimulates another gene to produce p21 which is another protein molecule. The p21 protein in turn interacts with cdk2 which is another protein that stimulates cell division. If for any reason p21 binds cdk2, the cell cannot continue through the cell cycle and does not

The First Emperor of China, Qin Shi Huangdi's leadership skills, main Research Paper

The First Emperor of China, Qin Shi Huangdi's leadership skills, main achievements and main accomplishments - Research Paper Example It was protected from adjacent states and barbarian tribes with natural barriers. Therefore this region became one of the earliest centers of iron metallurgy in ancient China. Trade with northern neighbors and states of Central Asia and agriculture were basic branches of economy. Before 500BC state of Qin did not take an active part in an internecine struggle of Chinese kingdoms and was considered relatively weak. Strong, persistent leaders and gifted commanders were required to use current potential in full scope. Shang Yang (390BC - 338BC) and Han Fei (280BC – 233BC), who had been statesmen at the end of the Warring States period, strengthened position of Qin among its competitors. Both of them were â€Å"credited with fostering Qin’s growth and categorized somewhat loosely as ‘Legalists’. They both had visited other kingdoms; and both met a violent death thanks to animosities.† (Loewe 12 - 18) As a leader and reformer Shang Yang could be compared with Qin Shi Huangdi, because they strived for building military-bureaucratic state. Both of them rejected principles of Confucianism such as hierarchy, patriarchal concept of power, family clans etc. According to Shang Yang, idleness and lack of discipline are the main reasons of state decline. Lack of governmental control over them causes economic and agricultural recession. Reforms of Yang and Huangdi weakened positions of patrimonial aristocracy as the ruling class, because preliminary they had exclusively comprised officialdom. â€Å"The situation changed when Shi Huang Di successfully unified China under Qin in 221 B.C. with Li Si as his chancellor, by using effective military forces formed by Shang Yang’s reforms. After unification, the emperor decided to abolish feudalism and adopt Junxianzhi, a centralized system in which all the regions are governed by aristocrats appointed by the emperor, rather than as an indi vidual