Common Assessment Topics - Essay Example

Common Assessment Topics Gene Therapy for Cancer Cancer results when a cell undergoes multiple mutations, which cause it to begin proliferating in an unregulated manner. Cancer cells differ from normal neighboring cells by several types of phenotypic changes the most significant of which are rapid rate of division, invasion of new tissue, elevated metabolic rate, and abnormal shape. Some cancer-promoting mutations may be transmitted to the germ line, whereas others spontaneously arise in the lineage of a particular somatic cell. Several techniques exist for identifying cancer-promoting mutations. After identification, cells bearing such mutations can be cloned in order to be studied in an attempt to learn how to control them (Peacock, 2010). For decades now, radiotherapy, chemotherapy, and surgery have been the only effective methods of treating cancers. However, these methods fail to eliminate cancerous cells in some patients. Such patients may be helped by gene therapy, a new and promising way of treating cancer. Gene therapy is the insertion of a foreign functional gene into specific cells of a patient to repair an acquired mutation, correct an inborn metabolic error, or provide a cell with a new function. The understanding of cancer at the molecular level has improved tremendously. Among the promising approaches to emerge in this area is the possibility of utilizing gene therapy to target and destroy selective tumor cells. This can be achieved by using this technique to correct an abnormality in tumor suppressor genes, especially P53, and prevent over expression of oncogenes such as K-RAS, which has been established to be a characteristic of various malignancies. Correction of an abnormality in a tumor suppressor gene can be accomplished using gene therapy by inserting a copy of the wild-type gene into the DNA. Insertion of the wild-type P53 gene into tumor cells that are deficient of P53 has been shown to induce death of tumor cells. The implications of this discovery are enormous. Alterations in P53 are the most common type of mutations in human cancers. It is possible to block the over expression of an oncogene at the genetic level by integrating it with an antisense gene with a transcript that selectively binds to the oncogene RNA. This impairs the oncogene’s capacity to direct the production of protein. Scientists have verified the effectiveness of this procedure by both in vivo and in vitro experiments, which have demonstrated that when an antisense vector of K-RAS is integrated into lung cancer cells over expressing their K-RAS, their tumor activity decreases (Peacock, 2010). Unfortunately, the use of gene therapy to treat cancer is not yet fully effective due to a number of difficulties which are yet to be overcome. The most important of these difficulties is the lack of efficient systems of gene delivery. Gene therapy can only be effective if a normal gene is successfully delivered into several million cells in a tissue. These cells have to be the targeted tumor cells in the correct tissue. On achievement of a successful gene delivery, the genes must then be activated to produce the protein it encodes. Gene delivery and activation have turned out to be the most complicated parts of the gene therapy process. Although a number of gene delivery techniques exist, including viral and non-viral, none of them is completely reliable. Researchers need to conduct further studies to come up with better techniques of gene delivery and activation (Peacock, 2010). Paternity Testing Paternity testing refers to genetic analysis carried out to establish whether or not two individuals have a biological father-child relationship. There are various reasons for carrying out a paternity test. A man may seek to have a paternity test carried out, when he learns that a relationship he was in many years back resulted in the birth of a child. In this case, they conduct the paternity test to confirm whether they truly are the biological father of the child. A man may also have a paternity test when he suspects his wife of infidelity or when he reunites with a child he was separated from many years back, and wants conclusive DNA evidence of the relationship. On the other hand, a mother may request for a paternity test in order to establish paternity and, therefore, obtain financial or emotional support for the child’s upbringing (Lowenthal, 2012). Paternity testing is carried out through DNA profiling. An individual derives his genetic material from that of both his parents. Therefore, comparing the DNA sequences of two individuals can show whether one was derived from the other. This is established by looking at certain sequences to determine whether one was copied verbatim from the other. If certain similarities are present, then this provides absolute proof that the two individuals have a biological father-child relationship. The testing process begins once the laboratory team receives all the specimens required for testing. Various techniques are used for analysis, but the most common is the Polymerase Chain Reaction (PCR) testing. In this procedure, the lab removes all the proteins and other contents of the cell in order to isolate pure DNA. The lab then examines locations called loci on each sample of DNA. This will provide two readings for each locus since all individuals bear two copies of every chromosome. On completion of loci testing, the readings obtained are compared. For each tested individual, the readings have two numbers. A child’s numbers for each locus must match one of the numbers from the mother for that locus. The other number of the child’s locus will match that of his biological father. Comparison of the Y chromosome can be carried out to establish the paternity of a male child. This is because the Y chromosome is transferred directly from father to son. Samples for the DNA profiling can be obtained by buccal swab, blood, or umbilical cord collection (Lowenthal, 2012). Genetically Modified Foods Genetically Modified Foods are crop plants produced for human and animal consumption by using genetic engineering techniques. These plants have undergone modification in the lab to enhance desired traits such as improved nutritional content or increased resistance to herbicides. Traditionally, enhancement of desired traits was carried out through selective breeding, mutation breeding, and somaclonal variation. In mutation breeding, scientists expose an organism to radiation or chemical mutagens in a bid to induce a non-specific but stable change (Peacock, 2010). However, conventional methods of plant breeding are often inaccurate and time-consuming. In contrast, genetic engineering techniques can result in the production of plants bearing the exact desired trait in a much shorter time than conventional breeding techniques and with great levels of accuracy. For example, plant geneticists isolated a gene that imparts drought tolerance and incorporate it into a different plant which gains the desired trait of drought tolerance, as well. In addition to genetic engineering involving plant to plant transfer, geneticists can also transfer genetic material from non-plant organisms to plants. For example, genes from Bacillus thuringiensis (B.t.), a naturally occurring bacterium, can be transferred to corn plants to induce pest resistance. These genes code for crystal proteins that are toxic to insect larvae, enabling a plant to acquire protection against harmful insects, especially the European corn borer. The issue of GMOs has raised a lot of controversy. The scientific community is in broad consensus that the risk GMOs pose to human health is roughly equal to that posed by conventional foods. Some of these risks include the development of new allergens and lack of information regarding the long-term effects of GM foods on human health. For example, plans to insert a Brazil nut gene into soybeans were abandoned for fear of inducing allergic reactions. However, critics still object to GM foods based on several grounds, the most significant of which are ecological concerns such as the interference of ecological relationships among organisms. For example, pollen from B.t. corn has been shown to result in elevated mortality rates of monarch butterfly caterpillars. Another concern is the possibility of cross-breeding between weeds and plants engineered for herbicide tolerance. This may result in the transfer of herbicide resistance genes to the weeds, which in turn become herbicide resistant as well. In addition, critics have raised concerns about the economic implications of GM foods, in particular, the fact that many GM crops are subject to international property law (Peacock, 2010). Fat Substitutes A fat substitute is a food product bearing the same stability, functions, chemical and physical characteristics as regular fat, but with fewer kilocalories than regular fat. This is because they lack the energy-dense fat granules that fats contain. Fat substitutes are used to produce low calorie and low fat foods. Fat substitutes are used in place of regular fat in a bid to avoid the detrimental effects that excessive fat has on health. Diet high in fat increases the potential risk for weight gain, heart disease, and some cancers. High levels of cholesterol in the blood are more prevalent in individuals that consume diets rich in saturated fats. This elevates the risk of developing coronary heart disease. The replacement of fat with fat substitutes in food enables the maintenance of its original quality without the risk of fat consumption (Coulston & Boushey, 2008). Fat substitutes are divided into four classes depending on their nutrient source. The first category comprises carbohydrate-based fat substitutes. These fat substitutes contain plant polysaccharides instead of fat. They can be further classified into cellulose, fruit-based fiber, dextrins, hydrocolloid gums, grain-based fiber, pectin, and maltodextrin. The second category of fat substitutes comprises protein-based substitutes. They include microparticulate proteins such as simplesse and modified whey protein concentrate. The third category comprises fat-based fat substitutes such as modified triglycerides and sucrose polyesters such as olean. The last category comprises fat substitutes that are a combination of more than one food type. The most common are combinations of carbohydrate and protein such as Mimix, and combinations of carbohydrate and fats such as Optamax. Despite the potential benefits that fat substitutes provide, they have not escaped controversy. Critics have been calling for their ban citing negative impacts on health. For example, the approval of Proctor & Gambles’ Olestra by the FDA was met by massive opposition by numerous health advocacy groups and the public. Their main concern is that Olestra is neither digested nor absorbed. Therefore, it does not liberate fat-soluble vitamins A, D, E, and K. These vitamins are crucial factors in the body’s ability to fight cancer. Therefore, deficiency of these vitamins can increase the risk of developing cancer as well as that of developing various diseases of the liver and blood. Some studies have revealed that ingestion of fat substitutes may lead to intestinal cramps and diarrhea. All these research revelations indicate that not enough studies have been carried out to ascertain the safety of fat substitutes. Therefore, further research is necessary before fat substitutes can be considered entirely safe (Coulston & Boushey, 2008). Sugar Substitutes Sugar substitutes are food additives that impart the taste of sugars to food, but often liberate less energy than sugar when metabolized in the body. Sugar substitutes can be classified into natural and synthetic. Synthetic sugar substitutes are commonly known as artificial sweeteners. There are several reasons why sugar substitutes are used in food and drinks. Firstly, they assist individuals to lose weight since they replace high energy sugar with other sweeteners that have little energy. Secondly, sugar substitutes such as xylitol assist in dental care. They are tooth-friendly because the microflora of dental plaque does not ferment them. Thirdly, sugar substitutes assist individuals with diabetes mellitus to regulate their blood sugar levels easily. Sugar substitutes enable them to enjoy a varied diet while simultaneously limiting their sugar intake. Sugar substitutes that are commonly used in food are aspartame, cyclamate, saccharine, stevia, sucralose, lead acetate, and mogrosides. Mogrosides and stevia are natural sugar substitutes whereas aspartame, cyclamate, saccharin, sucralose and lead acetate are artificial sweeteners. Aspartame is protein-based since it is derived from amino acids phenylalanine and aspartic acid. It is a white powder with a crystalline form and is 200 times as sweet as sugar. It is quite unstable and breaks down into its constituents at high temperature. This property makes aspartame unsuitable for use as a baking sweetener. Its stability is increased by acidity, making it suitable for use in soft drinks. A lot of research has been carried out to establish the safety of aspartame and other sweeteners. Critics have made multiple claims against its safety, including psychiatric and neurological side-effects as well as links to cancer. This has led to extensive research that has made aspartame the most rigorously studied food ingredient. However, multiple reviews by governmental regulatory authorities and peer-reviewed articles have analyzed the results of research conducted on this issue and concluded that there is no health hazard in the consumption of aspartame at current levels. Producing Transgenic Plants Transgenic plants are plants whose genetic make-up has been altered in order to introduce new traits using recombinant DNA technology. They contain an insertion of DNA from a separate organism. This genetic modification enables the plant to acquire a specific desired trait such as improved nutritional content and resistance to pesticides and diseases. The first step in the production of transgenic plants is the isolation of DNA that codes for the protein which brings about the desired trait. The isolated DNA is inserted into a plasmid, which is a segment of DNA that can duplicate itself. Bacteria are used to develop plasmids because they readily accept them even if they contain DNA that they cannot recognize. The plasmid is inserted into bacteria, which is then grown in large numbers. The bacterium most commonly used for this purpose is Agrobacterium tumefaciens. The next step is to dip the targeted plant in a large amount of these genetically modified bacteria. The plant must be flowering in order to ensure that the plant’s egg cells acquire the plasmid. This ensures that the new genetic make-up will be transferred to the offspring so that they may acquire the desired trait. Agrobacterium tumefaciens possesses the natural ability to insert DNA into plant cells (Peacock, 2010). The desired traits that recombinant DNA enable transgenic plants to obtain include improved nutritional quality, disease resistance, insect resistance, herbicide resistance and salt tolerance. In addition, transgenic plants can also be used to produce biopharmaceuticals. Genes encoding for proteins to be used in human medicine are inserted into plants which express them. The production of transgenic plants has also been faced with controversy. Transgenes in commercial plants may pose a risk to non-target species. For example, a gene for herbicide resistance inserted into corn may end up in weed species, which would in turn become much more difficult to control. There is also the risk of transgenic crops mixing with non-transgenic food crops. However, there is no scientific evidence that this occurrence poses a threat to human health. A potential future development in transgenic plant technology includes the ability to insert DNA fragments with more than one gene to modify complex traits (Peacock, 2010). References Coulston, A. M. & Boushey, C. J. (2008). Nutrition in the prevention and treatment of disease. London: Elsevier Academic Press. Lowenthal, M. (2012). The paternity test. Madison: Terrace Books. Peacock, K. W. (2010). Biotechnology and genetic engineering. New York: Infobase Publishing. Read More