Structure Of Dna Essays - Genetics, Molecular Biology, Nucleic Acids

Structure Of Dna The ?Thread of Life?, is deoxyribonucleic acid, also known as DNA. This molecule which is the bases of life, is spiral shaped and found in the nucleus of cells. DNA has the genetic code for bodies, controls development of embryo's, and is able to repair damage caused to itself. All DNA molecules have linked units called nucleotides. These nucleotides have sub-units that have 5 carbon sugars that are called deoxyribose. DNA is composed of four bases called adenine, thymine, guanine, and cytosine. These are some of the main principles of DNA. What we know today about structure of DNA begins in 1868 when a Swiss biologist Friedrich Miescher did the first experiments on the nuclei of cells. Miescher used the nuclei of pus cells from old medical bandages. In these pus cells he found What We know today about structure of DNA begins in 1868 when a Swiss biologist Friedrich Miescher did the first experiments on the nuclei of cells. Miescher used the nuclei of pus cells from old medical bandages. In these pus cells he found phosphorus with a substance he called nuclein. This nuclein has an acidic portion which is classified as DNA. Another scientist Thomas Hunt Morgan made an important discovery around 1900. He observed that certain characteristics were inherited quickly through numerous generations of fruit flies. So he made the conclusion that these genes must be near one another on the chromosome. In 1943 Oswald Avery, Colin MacLeod, and Maclyn McCarty, three scientists working in the Rockefeller institute, preformed an exper iment by taking DNA from a virulent (disease-causing) strain of Streptococcus pneumonae and transformed a non-virulent (inactive) form back to a virulent form. Avery, MacLeod, and McCarty discovered from their experiments that DNA carried a virulent message that can be transferred into the recipient of non-virulent cells. This proved that DNA was a carrier of genetic information. An important discovery of the 1940's was the discovery by Erwin Chargaff who established that ?heredity's alphabet? which are the four bases adenine (A), guanine (G), thymine (T), and cytosine(C) can occur in different orders in different organisms. In 1953 James Watson and Francis Crick put forth a radical new idea about DNA. Their idea suggested that the DNA molecule was made up of two helical chains instead of three intertwined chains as previously thought. Today we have a strong knowledge of DNA and scientists are applying that knowledge to a three billion dollar project called the human genome project. This project will examine the structure of human DNA and map out every single gene in the human body and will take 15 years. The strong knowledge that we have of DNA allows the scientist to map out the genes at about 1 to 2 per day. This may not seem to be a very fast rate but scientists have already found the genes that cause diseases such as Hunnington's, Lou Gerhig's, and the ?Bubble-Boy? disease. Another way that we use our strong knowledge of DNA is in criminal identification. This plays a major role in today's society. Because each person's DNA is different (except in identical twins) police officers can take blood or semen samples from a crime scene and take them to the lab for identification. This can insure the guilt or innocence of a suspect. An example of this is the O.J. Simpson case where investigators tried to match O.J.'s DNA to the DNA at the scene of the crime. Another way scientists apply their knowledge of DNA today is by using special enzymes called restriction enzymes that cut through the phosphate of DNA and these cut ends are called ?sticky ends? because they easily attract other tails from other DNA. Scientist use these restriction enzymes for genetic engineering by removing a gene from one organism to another. In the future DNA has great possibilities for the betterment of mankind and also the detriment. The most obvious and controversial possibility would be the cloning of humans. Scientists have already cloned sheep and other such organisms but have yet to take the step for cloning a human even though the technology is in place, the ethics of this may not be. The method to arrive at is quite

GRE General Test Essay Topics

GRE General Test Essay TopicsGRE General Test Essay Topics is the topics you must study in your preparation for the test. If you have not studied these topics or had to read them off of the board, then you will be shocked at what they cover. This makes GRE General Test Essay Topics an important aspect of a test prep course, whether or not you decide to take it for your exam.The first part of GRE General Test Essay Topics is their focus on the content of the exam. In general the questions are not designed to force you to memorize, but rather to force you to think and use your reasoning skills. This is one reason why it is so important to study every section of the test. You will not want to do well on the first section because you did not really study the subject matter.By studying every section thoroughly you will know exactly what you need to study and you will understand that every content you need to know is covered in the previous sections. You will then be able to determine how well you studied for the different sections and if you would want to include the ones you struggled with in your score. However, if you think you have already done enough studying and would like to see if you have a low score, you can choose to take GRE General Test Essay Topics in both verbal and math.You should also pay attention to the different areas of the language. You will be asked a lot of vocabulary and grammar questions. These topics are always fairly easy, but it will be a good idea to study these topics since they are a huge part of your score. To help you with this, make sure that you bring a pen and paper along with you on the test day and that you keep a high quality dictionary handy at all times.The second part of GRE General Test Essay Topics is their focus on essay and analytical essay writing. Thesetwo writing styles are important to know about if you plan to take the test. They should be part of your test prep course in order to understand the difference between essays in written form. Since the Essay Topic includes essays and the Writing Essay is one of the few sections where you will likely be called upon to write, you should spend some time studying and practicing writing strategies in both essay and written form.The third part of GRE General Test Essay Topics focuses on the content of your essays. Your essay topics should include your research and experience, as well as you personal opinions. It is not enough that you simply agree with the topic, but you should also state your reasoning and further elaboration in support of your arguments.Overall, GRE General Test Essay Topics is a great way to prepare for the test. The exam itself is not easy, but knowing what you should expect can really help you prepare for the exam. If you have not practiced writing essays, now is the time to do so.