The Nature of Truth Essay Example | Topics and Well Written Essays - 500 words

The Nature of Truth - Essay Example Charles Darwin suggested the theory of evolution, by natural selection. He collected multiple pieces of evidence to support his idea so that he can make the idea realistic to the people. After looking at all the evidence, he came up with the conclusion that the theory of evolution was the beat explanation that he could come up to support the discoveries that he found during his research (Scott, 2008). The history of all living things is usually documented in the multiple lines of evidence, which form a convergence and tell the story of life as time passes. The first piece of evidence of evolution is found in fossil remains that have been discovered in time. These fossils serve as snapshots of history, and they are used to illustrate the evolutionally changes that have taken place over time. Fossil remains started being discovered as early as in the seventeenth century. Each new fossil that is discovered brings new clues as to the understanding of human history (Scott, 2008). Other evidence ids brought about by the study of embryology and the observation of similarity between species. Embryos of early vertebrates look similar. These species differs in their genetic structures due to the genetic changes that every organism undergoes so as to adapt to the environment, evolution was also brought about by natural selection where nature choose the beat species that are best adapted to the environment (Scott, 2008). The theory of evolution is supported by many pieces of evidence; Biogeography is the study of a number of species in an area over a given period. This study gives the idea that if the evolution theory is true, then species that are related should be found in the same geographical area this is in the exemption of the animals that have a high mobility rate like birds (Scott, 2008). There are other theories that are against the theory of evolution. These theories include the creation theory, the big bang

What Causes Cancer Mutations Essay Example | Topics and Well Written Essays - 1500 words

What Causes Cancer Mutations - Essay Example As genes are the basic control machine of the cells, alteration of any kind may bring devastating consequences, or malignancy. When compared with the normal cells, where damage of any kind is taken care by the repair system, tumor cells do not have any repair mechanism for the damaged DNA and there is a constant proliferation of cells without displaying senescence hence, generating a series of abnormal cells, with altered cellular pathways for uncontrolled proliferation, figuring malignant tumors (Alberts 2007; Katzang et al. 2009). The Genesis of a Cancer Cell A normal cell turns into a cancer cell because of one or more mutations in its DNA, which can be inherited or acquired. Mutation is sudden abrupt changes that occur in the genetic material i.e. the DNA of the cell. This genetic material is facilitated by various agents called mutagens. Mutagens can be either physical agents such as UV radiations, X-rays etc or they could be some chemical agents which are capable of producing c hanges in the cell by reacting with cellular macromolecules. These chemical agents form bond with the cellular macromolecules, thereby alter their normal structures. If they combine with the genetic material, the peptide formation is affected. Thus, these mutagenic agents affect the normal well being of the cell and when such a defective cell replicates the cellular modification is also passed on. These cellular alterations may lead to cancer, where the carcinogenic agents (cancer causing) are capable of altering the cell division leading to the uncontrolled proliferation of the cell (Alberts 2007; Chemical Carcinogens, Web.). In case of the breast cancer, woman who inherits a single defective copy of either of these tumor suppressor genes BRCA1 and BRCA2 displays an augmented risk of developing breast cancer. However, carcinogenesis is a complex, multistage process, usually involving more than one genetic change. Other epigenetic factors responsible for carcinogenesis involve epige netic factors, such as level of hormones in the body, exposure to carcinogens and tumor promoting agents. These epigenetic factors do not produce cancer by themselves but enhances the likelihood of genetic mutation(s) resulting in cancer (Katzang et al. 2009). These genetic changes are categorized as - A. The activation of proto-oncogenes to oncogenes: Proto-oncogenes are the normal genes present in the cells and are responsible for controlling cell division, cell differentiation and apoptosis. A triggering factor such as a virus or exposure to any carcinogen brings malignant changes in the cell. B. The inactivation of tumor suppressor genes: A cell has the mechanism to protect itself from uncontrolled proliferation and tumor formation due to expression of genes called tumor suppressor genes. These genes possess the ability to suppress malignant changes and are also referred as antioncogenes. Mutation in proto-oncogenes or tumor suppressor genes results in the proliferation of tumor . Thus, a loss of function of tumor suppressor genes can be the critical event in carcinogenesis (Rang et al. 2007; Katzang 2009). More than 30 tumor suppressor genes as well as more than 100 dominant oncogenes have been found to be associated with various types of cancers (Rang et al. 2007). Characteristics of Cancer cells The genetic basis of cancer has been revealed through numerous animal models. The Cancer Genome Atlas aims at methodically differentiating the configurational source of cancer, through recognition of the genomic mutations linked with every cancer form. A corresponding progress and description forms the basis of understanding growth and external appearance of the cancer or tumor called the phenotype of the cancer, is essential for designing drugs that can