Monday, October 20, 2014
DNA Profiling
Modern DNA technology methods have rapidly transformed the field of forensics. Forensics is the scientific analysis of evidence for crime scene investigations and other legal proceedings. The most important application of forensics is DNA profiling. DNA profiling is the analysis of DNA samples to determine whether they came from the same individual. First, DNA samples are isolated from the crime scene, suspects, victims, or other evidence. Second, selected markers from each DNA sample are copied many times, producing a large sample of DNA fragments. And last, the amplified DNA markers are compared, providing data about which samples are from the same individual. -Biology book pg. 242
Genetically Modified Organisms
For many years, scientists have selectively bred agricultural crops to make them more useful. In recent years, DNA technology has quickly replaced traditional breeding programs. Genetic engineers have produced many different varieties of genetically modified organisms. GMO's are organisms that have acquired one or more genes by artificial means. A common vector used to introduce new genes into plant cells is a plasmid from the soil bacterium Agrobacterium tumefaciens called the Ti plasmid. With the help of a restriction enzyme and a DNA ligase, the gene for the desired trait is inserted into a modified version of the plasmid. Then the recombinant plasmid is put into a plant cell, where the DNA carrying the new gene integrates into one of the plant's chromosomes. Finally, the recombinant cell is cultured and grown into a plant. With an estimated one billion people facing malnutrition, GMO crops may be able to help many hungry people by improving food production, shelf life, pest resistance, and the nutritional value of crops. -Biology book pg. 239
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Sunday, October 19, 2014
Gene Cloning
To start off the process of gene cloning, biologists isolate two kinds of DNA, a bacterial plasmid and the DNA from another organism that includes the gene that codes for protein V. The DNA containing gene V could come from different bacterium, a plant, a nonhuman animal, or even human tissue cells. Both the plasmid and the gene V source DNA are treated with an enzyme that cuts. The cells DNA is cut with the same enzyme. The cut DNA from both sources are mixed. DNA ligase is added joining the two DNA molecules by way of covalent bonds. The recombinant plasmid is taken up by a bacterium through transformation. The recombinant bacterium then reproduces to form a clone of cells, each carrying a copy of gene V. This step is actual gene cloning. This process can be used to create a number of products. Copies of gene itself can be the immediate product, used in plants. Other times, the protein product of the cloned gene is harvested and used, to make "stoned-washed" blue jeans. A protein can also be used to dissolve blood clots in heart attack therapy.
Colon Cancer
In just one year alone, more than 100,000 Americans will get colon cancer. The colon is the main part of the large intestine. It takes more than one somatic mutation to produce a full-fledged cancer cell. Colon cancer begins when an oncogene arises or is activated through mutation, causing unusually frequent division of apparently normal cells in the colon lining. Later, additional DNA mutations cause the growth of a small benign tumor in the colon wall. Still more mutations eventually lead to formation of a spreading tumor. The requirement for several mutations explains why cancers can take a long time to develop. The actual number of mutations is usually around six. Multiple changes must occur at the DNA level for a cell to become fully cancerous. Once a cancer promoting mutation occurs, it is passed to all the descendants of the cell carrying it. The fact that more than one somatic mutation is generally needed to produce a full-fledged cancer cell may help explain why the incidence of cancer increases with age.
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Thursday, October 16, 2014
Rosalind Franklin
Rosalind Franklin was born in London England in 1920. As a little girl she was astoundingly smart for her age. Her parents sent her to St. Paul's Girls School where she graduated a year early and went to Cambridge University to major in physics and chemistry in 1938. There, she was introduced to x-ray crystallography. She then joined the war effort doing research on coal. Her research led to better gas masks, publishing five landmark papers, and being awarded her PhD. After the war she landed a research position in Paris and took on x-ray diffraction. She spoke in conferences and published articles in journals. Over a short period of time, she exceeded unsafe levels of x-ray radiation and was put out of the lab for a few months. So she decided to attend King College London where she was hired by JT Randall to discover DNA in January 1951. When she went in she was supposed to be Maurice Wilkins' assistant but he was away on vacation. He come back to find that Franklin took over his lab as well as his PhD student, Raymond Gosling, which was all due to miscommunication from the leader Randall.
James Watson comes to London to study DNA where he teams up with Francis Crick to make a model of the DNA structure. Meanwhile, Franklin discovered two distinct forms of DNA, A and B. In November 1951, Crick sent Watson to Franklin's lecture about her A and B discovery to try and get information to help them build they're DNA model. Within a week after her lecture, they invite her to see they're model at Cambridge University where they were embarrassed after she told them it was completely wrong. So Lawrence Bragg, the head of the Cavendish Laboratory, told them they couldn't make anymore models because they humiliated him.
In May 1952, Franklin sets up an x-ray diffractometer to take a better picture of the B form. In her results, she gets a clearer, sharper image of B and labels it Photo 51 and puts it safely away while she works on form A. At the end of the year, she decides to leave Cambridge University due to the rude people but kept up her work and study. Some how in the mix of her leave, her Photo 51 gets leaked to Wilkins. Linus and his son Peter Pauling did model building and knew almost as much as Franklin did. Watson warned Franklin that Pauling was going to beat them to the DNA secret if she didn't go in with him and Crick and publish it but she said no. Wilkins shows Watson Photo 51 and Watson shows Crick and they begin making another model with permission from Bragg on February 4th, 1953. On February 28th, 1953, the model was complete. Franklin was amazed and didn't understand how they knew without her detailed photos. Articles were released in Nature on April 25th, 1953 stating Crick and Watson's untruthful discovery and gave no mention of Franklin's photo.
After leaving Cambridge, Franklin attended Birkbeck University of London where she led the virus research lab from 1953-1958. There, she collaborated with Aaron Klug working out the complex structure of a virus and locating it's infectious element. Together, they won a Nobel Prize. In 1956, she celebrated her 36th birthday by visiting universities in California and climbing Mt. Whitney. At the end of her trip, she began to suffer from severe abdominal pains. When she returned home, she was diagnosed with cancer believed to be caused from years of x-ray radiation. Even with the disease, she still studied every day, feeling as if she were too busy to die. She soon died on April 16th, 1958.
In 1962, James Watson, Francis Crick, and Maurice Wilkins won the Nobel Prize for the discovery of the structure of DNA. None of the three acknowledged Rosalind Franklin for her unknowing contribution to the discovery. In 1968, James Watson published a best seller book entitled The Double Helix. In the book, he admits he wouldn't have ben able to finish his work without her findings and that he used them without permission. When Aaron Krug was awarded the Nobel Prize, he honored her contribution to the study of DNA in mentioning her name and her hard work.
James Watson comes to London to study DNA where he teams up with Francis Crick to make a model of the DNA structure. Meanwhile, Franklin discovered two distinct forms of DNA, A and B. In November 1951, Crick sent Watson to Franklin's lecture about her A and B discovery to try and get information to help them build they're DNA model. Within a week after her lecture, they invite her to see they're model at Cambridge University where they were embarrassed after she told them it was completely wrong. So Lawrence Bragg, the head of the Cavendish Laboratory, told them they couldn't make anymore models because they humiliated him.
In May 1952, Franklin sets up an x-ray diffractometer to take a better picture of the B form. In her results, she gets a clearer, sharper image of B and labels it Photo 51 and puts it safely away while she works on form A. At the end of the year, she decides to leave Cambridge University due to the rude people but kept up her work and study. Some how in the mix of her leave, her Photo 51 gets leaked to Wilkins. Linus and his son Peter Pauling did model building and knew almost as much as Franklin did. Watson warned Franklin that Pauling was going to beat them to the DNA secret if she didn't go in with him and Crick and publish it but she said no. Wilkins shows Watson Photo 51 and Watson shows Crick and they begin making another model with permission from Bragg on February 4th, 1953. On February 28th, 1953, the model was complete. Franklin was amazed and didn't understand how they knew without her detailed photos. Articles were released in Nature on April 25th, 1953 stating Crick and Watson's untruthful discovery and gave no mention of Franklin's photo.
After leaving Cambridge, Franklin attended Birkbeck University of London where she led the virus research lab from 1953-1958. There, she collaborated with Aaron Klug working out the complex structure of a virus and locating it's infectious element. Together, they won a Nobel Prize. In 1956, she celebrated her 36th birthday by visiting universities in California and climbing Mt. Whitney. At the end of her trip, she began to suffer from severe abdominal pains. When she returned home, she was diagnosed with cancer believed to be caused from years of x-ray radiation. Even with the disease, she still studied every day, feeling as if she were too busy to die. She soon died on April 16th, 1958.
In 1962, James Watson, Francis Crick, and Maurice Wilkins won the Nobel Prize for the discovery of the structure of DNA. None of the three acknowledged Rosalind Franklin for her unknowing contribution to the discovery. In 1968, James Watson published a best seller book entitled The Double Helix. In the book, he admits he wouldn't have ben able to finish his work without her findings and that he used them without permission. When Aaron Krug was awarded the Nobel Prize, he honored her contribution to the study of DNA in mentioning her name and her hard work.
Tuesday, October 14, 2014
Charles Darwin
Charles Darwin introduced the theory of evolution to the world more than 200 years ago. He published a book entitled On the Origin of Species by Means of Natural Selection. In 1841 Charles Darwin set out on a ship called the Beagle to explore the South American coast. On his voyage he took detailed notes and collected fossils, bones, plants, insects, and many other things. From his studies, he came to realize that the world isn't just 6,000 years old, as the book of Genesis states in the bible, but that it is over hundreds of thousands of years old. When he returns home, he put all of his evidence that he collected over his 5 year trip and seen that he discovered 69 different species of beetles as well as different species of butterflies, dragon flies, birds, and many other organisms including plants. He gave a skull head he found to Richard Owen he informed him that his finding was the skull of a ground sloth that is a species that is now extinct that lived over 10,000 years ago.
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