Why is sexual reproduction so common in nature?
Why is sexual reproduction so common in nature? One of the greatest challenges for evolutionary biology is explaining the widespread occurrence of sexual reproduction, and the associated process of genetic recombination. Sexual reproduction involves one individual combining half its DNA with half of DNA of another individual, so that the offspring is only half genetic copy of each parent. However, in asexual reproduction, the offspring are genetic copies of the parent. Thus, sexual reproduction poses an evolutionary problem because it seems to be half as efficient a method of reproducing as asexual reproduction. Asexual females can potentially produce twice as many daughters as sexual females, so that the ratio of asexual to sexual females should initially double each generation, resulting in the 'two-fold cost of sex'.? In addition to this 50% cost and the dilution of the individual's genome, sexual reproduction also presents other disadvantages in comparison to asexual reproduction. First and foremost there is the cost of recombination - favourable gene combinations that have increased in frequency under the action of natural selection are broken up. Secondly, the process of sexual reproduction requires a significant cellular-mechanical cost as sex requires meiosis, syngamy and karyogamy. A great amount of time is taken up by these three processes alone, and far
Cloning pros and cons
Cloning A group of genetically identical offspring produced by asexual reproduction is called a clone. The nucleus of every cell of an individual contains the genetic information needed to develop the entire organism. It is therefore possible under suitable conditions to produce a whole organism from a single cell. If a cell divides mitotically it will produce a clone. If each cell of the clone is separated and allowed to develop into the complete organism, a group of genetically identical offspring is formed. This is known as cloning. (2). Two very different procedures have been referred to as "cloning": * Embryo cloning has been successfully carried out for years on many species of animals. Some limited experimentation has been done on human embryos. * Adult DNA cloning has been used to clone a sheep, but was not tried on humans until 1998-DEC (3) Humans often think of themselves as being superior to other animals (not to mention plants, fungi, bacteria and so on) and therefore having the "right" to exploit other organisms for their own benefit. (1) The cloning of the sheep, Dolly, in 1997 was an inevitable consequence of the progress being made in genetics and biotechnology. It raises the possibility of breeding many identical copies of animals including transgenic animals, showing desirable features. One of the ethical concerns is that the techniques could be
Embryo Screening. The embryo screening, also referred as PGD (preimplantation genetic diagnosis), is a procedure tested on an embryo to identify any unwanted diseases that is found in the genes of the embryo.
Embryo Screening Settling down and starting a family is what many couples have in mind. It's a life changing decision the many indivisual choose to endure, however, obstacles and complications have delayed couples from fulfilling their goal. Leaving the chances of pregnancy aside, couples try to prevent many issues that occur with their newborns - infectious and complicated diseases, deformities and abnormalities. In many cultures and races, it is customary, or even the norm, to marry close relatives. This scientifically has been proven to increase the chances of having your offspring inherit the diseases that have been in the past generations, such as diabetes, cancer, anemia and leukemia. [8] One type of solution that has been discovered is embryo screening and human genetic engineering. The embryo screening, also referred as PGD (preimplantation genetic diagnosis), is a procedure tested on an embryo to identify any unwanted diseases that is found in the genes of the embryo. This then enables the couples to be aware of the problems that they might be facing if they do get pregnant, and leaving their embryo untouched. After enlightening couples about the genetic diseases found in the genes, they have to whether to go through the PGD and modify the genes to contract the ones that contain the genetic information about the disease, abnormality, or deformity. "PGD involves
Genetically modified crops - Do we know all the answers?
Genetically Modified Crops. Do we know all the answers? Genetic Modification is the method of obtaining individual genes, which are then copied and repositioned into another living organism to modify its genetic code and incorporating or removing particular characteristics into or from an organism.1 There are many viewpoints on the issue genetic modification, some scientifically based on environmental factors and potential economic growth, others concerning ethical, moral and social perspectives. Ever since the breakthrough of genetic modification, deliberation has surrounded all issues involving this controversial topic. Many organizations have published books, videos, and leaflets arguing their side of this debate. Advances in GM biotechnology, such as the incorporation of the gene which stops the Arctic Flounder from freezing, has been placed into the genetic sequence of strawberries to stop them shrivelling in the cold British weather2, these 'modifications' have led to many intrinsic and extrinsic moral issues arising from this "new" technology. Dr Robert Farley of the Monsanto Institute, USA3 believes that genetic modification of crops for human consumption is a much more efficient and effective way of creating more resilient wheat crops than traditional cross-pollination. This is because genetic modification is more specific in changing a particular gene,
Agricultural Issues: Genetic Modification.
Agricultural Issues: Genetic Modification Scientists are developing ways to make new genetically modified (GM) food that could transform the way we feed ourselves. GM crops may enable more food to be produced from less land using less water and fewer chemicals. However, some people question whether this "gene revolution" will really reduce hunger in the world. Others worry that it is being pushed too quickly without enough consideration of its long term impact. Throughout the world there are drastic inequalities in food supply with the emergence of areas of surplus and famine. The cause of such inequalities vary from physical to human and political. Most of the responses to these problems have been driven by high income, high technology MEDC's or trans-national companies. The impacts of the Green Revolution, intensification of farming and the development of genetically-modified foods have varied. Some are economic while others have been social or environmental: some have brought benefits, while others have created problems and some may be focused upon the environment e.g., organic farming. Throughout the world genetic modification has been used freely for more that a decade as a research tool for medical purposes and in food ingredients. It holds exiting promise, not only for conquering disease, eliminating pests and contributing to the knowledge economy but for enhancing
Cloning means making a living thing from another living thing such as a plant or animal. The process uses the genes of the first so they both have identical DNA.
TRANSLATION PRACTICE -1st year CLONING Cloning means making a living thing from another living thing such as a plant or animal. The process uses the genes of the first so they both have identical DNA. Cloning isn't new. Nature has been doing it for billions of years with plants. Things like potatoes and grass send out shoots which can grow into a whole new plant. If you grow a plant from a cutting it's a type of cloning. And identical twins are naturally-occurring clones of each other even though they're genetically different from their parents. In the last few decades scientists have been trying to clone animals. They transplant DNA (the gene pattern which makes living things unique) from the cell of one animal into the cell of another which has had its DNA taken out. Now scientists in America have announced that they have created a clone of a human embryo. In 1997 Dolly the sheep became the first ever cloned mammal. Scientists in Scotland used a new type of technique. When Dolly was born months later, it had taken 276 tries to get it right. Since Dolly, cows, pigs, monkeys, rodents, cats, mules, horses and dogs have been cloned. Animals or plants with special qualities could be mass produced to help in the manufacture of important drugs. You could replace pets which have died or even repopulate endangered or extinct species. In 2001 the first
Cellular Reproduction
Cellular Reproduction Cellular Reproduction is the process by which all living things produce new organisms similar or identical to themselves. This is essential in that if a species were not able to reproduce, that species would quickly become extinct. Always, reproduction consists of a basic pattern: the conversion by a parent organism of raw materials into offspring or cells that will later develop into offspring. (Encarta, 2) In almost all animal organisms, reproduction occurs during or after the period of maximum growth. (Fichter, 16). But in Plants, which continue to grow through out their lifetime, therefore making the process more complex. Plants' reproduction is usually caused by a stimulant, mostly environmental or growth factors. The reproductive process, whether asexual or sexual always involves an exchange in hereditary material from the parent(s) so that the new organism may also be able to reproduce. Reproductive processes can be categorized in many diffrent ways although the most common is to put them into either asexual reproduction or sexual reproduction. Asexual reproduction is the process by which a single organism gives rise to two or more daughter cells. Most single celled organisms reproduce by the asexual process known as fission, which is commonly called mitosis. Fission (or Mitosis) is the division of one cell into two identical daughter cells.
The potential benefits and risks of genetically modifying food.
In this essay I will be looking at the potential benefits and risks of Genetically Modifying Food. The idea of genetically modifying food is, and has been, a subject of great debate for quite a while now, and all over the world GM food is available to buy. The argument for and against GM good is split into 4 main groups, the group that think GM is the way forward, and the way to reduce famine, increase health etc, the group that thinks that GM food is the way forward because it increases efficiency, i.e. no pesticides needed, faster growing, better yields etc, then there are the 2 groups against GM foods, those who fear GM foods to be damaging, and that we should only eat organic, and then there are those who believe that GM foods is playing god. Of course, not everyone fits into a single one of these categories, for example many people are on the fence about the issue, there are people who just don't care about the issue, and there are those who cross between the groups. There are some genuine Health risks that could arise from extensive genetic modification of foods, these risks include; New toxins and allergens in foods, Other damaging effects on health caused by unnatural foods, The creation of herbicide-resistant weeds, The spread of diseases across species barriers, Loss of bio-diversity in crops, The disturbance of ecological balance, Artificially induced
Gregor Mendel
Gregor Mendel Gregor Mendel was born on July 22nd, 1822 in Hyncice, Moravia which is now Czech Republic. He was born Johann Mendel into a poor farming family. His academic abilities were recognized by the local priest, who persuaded his parents to send him away to school at the age of 11. His grammar school studies completed in 1840, Mendel entered a two-year program in philosophy at the Philosophical Institute of the University of Olmütz (Olomouc, Czech Rep.), where he excelled in physics and mathematics, completing his studies in 1843. As his father’s only son, Mendel was expected to take over the small family farm, but he preferred a different solution to his predicament, choosing to enter the brünn monastery as a novitiate of the Augustinian order, where he was given the name Gregor. It was at the monastery where he was introduced to a diverse and intellectual community. However, in 1850, Mendel failed an exam introduced through new legislation for teacher certification and was sent to the University of Vienna for two years to benefit from a new program of scientific instruction. Mendel devoted his time at Vienna to physics and mathematics, working under Austrian physicist Christian Doppler and mathematical physicist Andreas von Ettinghausen. He also studied the anatomy and physiology of plants and the use of the microscope under botanist Franz Unger, an enthusiast
Is genetic modification morally wrong?
Is genetic modification is morally wrong? Genetic modification is methods that make it possible to change the pattern in genetic material. The genetic material found in cells in molecules called DNA, is the design for any living thing. I.e. plant, animals, bacteria, etc. Changing the pattern of DNA molecules ay make it possible to change the characteristics in the living organism. The ability to modify organism's genetic makeup has uses: <> Understanding the basic of plant, animals, including humans. <> Use in agriculture; better yield of crops and better for consumers. <> In animals: better health, livestock and humans. However genetic modification is doing more harm then good. Studies show the disadvantages of genetic modification. These studies show that GM crops and foods are harming the environment and could be harming wildlife and even humans. Crops that have been genetically modified (GM) to produce pharmaceuticals that can contaminate the food supply. There were scares that drugs that are produced by GM crops, were getting into the food supply such as cereal. 'Biopharma' grown for the drug, produced for medicines were getting mistaken for GM crops and ending up in American supermarkets as breakfast cereal. There has been a study that shows that crops that have been genetically modified to resist insects kill not just 'target insects' (borer and weevil) but
