History of DNA
Have you ever asked yourself “why my eyes are this color?“ Have you questioned why you look the way you do? All of your physical features come from our genetics. Those genetics are family traits that are passed down through our individual bloodline. All of these individualities come from what is considered the fundamental building blocks of life, DNA.
DeoxyriboNucleic Acid is the scientific name for DNA (SITE). A Swiss medical student named Johann Friedrich Miescher discovered DNA in 1868 (SITE). Miescher was investigating the white blood cells of pus from a surgical wound. It was there in these white blood cells that he found the “hot to manual” that defines what we look like. It is important to note, DNA is in every living creature. The discovery of DNA is not new to science, but what do you really know about it.
Even though Miescher discovered DNA in 1868, it would take another 80 years before DNA would be considered actual genetic material. The medical and scientific communities of Miescher’s era felt that DNA was too simple for consideration as genetic material. It was not until the 20th century when James Watson and Francis Crick discovered the double helix through x-rays, that DNA would be recognized.
Watson and Crick looked deeper into the DNA configuration and learned that the structure of DNA is actually is a coiled double helix on a 34 degree pitch (Hallick, 1995). This double helix structure is made from alternating sugar and phosphate bonds. Holding these sugar and phosphate bonds together is hydrogen. The four bases adenine, cytosine, guanine and thymine, attach to the sugar/phosphate bonds forming a complete nucleotide (Simon & Dickey, 2012). The neucleotoid repeats itself creating a ...
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...onucleic acid (dna). (2012, June 13). Retrieved from https://www.genome.gov/25520880
Diseases and conditions copd. (n.d.). Retrieved from http://www.mayoclinic.org/diseases-conditions/copd/basics/definition/con-20032017
Hallick, R. (1995). Introduction to dna structure. Retrieved from http://www.blc.arizona.edu/molecular_graphics/dna_structure/dna_tutorial.html
Protein synthesis. (n.d.). Retrieved from http://www.elmhurst.edu/~chm/vchembook/584proteinsyn.html
Moss, T. (2001). DNA-protein Interactions: Principles and Protocols. Totowa, N.J.: Humana Press
Role of enzymes in biochemical reactions. (n.d.). Retrieved from http://www.elmhurst.edu/~chm/vchembook/570enzymes.html
Simon; Reece; Dickey, E. (2012). Campbell Essential Biology with Physiology [VitalSouce bookshelf version]. Retrieved from http://digitalbookshelf.southuniversity.edu/books/9781256902089/id/ch04bx3
Francis Crick (American) and James D. Watson (Englishman) had a problem with DNA (Deoxyribonucleic Acid) in 1950 because the individual pieces could not be seen. They could be seen with x-ray crystallography which could be done in Kings College, London. They were convinced that DNA was a double helix spiral ladder that contained chemical strands of two to four. It consisted of two strands that were interwoven.
The following is a review of the book, The Double Helix, by James D. Watson that was published in 1968. Here the Norton Critical Edition will be used for page numbering and insights for this review, which was edited by Gunter S. Stent and published in 1980. The Double Helix is a personal recollection of the period of time when the structure of DNA was discovered. James D. Watson (Watson) along with Francis Crick (Crick) were the two scientists who published a paper in 1953 which purposed a structure for DNA. For the most part their structure has stood the test of time, and since that time period many people have wanted to know details of how they discovered DNA’s structure (pp. 3). Therefore Watson’s purpose in writing the book was to describe his personal view of the events that lead to discovery of DNA’s three-dimensional structure, when they happened in 1952-53. He is well qualified to give an account of these things, for he was there in the middle of everything; he was one of the main players. In order to describe the events, apart from his sharp memory, Watson used letters he wrote to his family to help him remember dates and details, as well as suggestions from his associates who reviewed his manuscript. In the following paragraphs I will summarize the text, and follow that with my own review of
The molecule consisted of a double helix with phosphates, deoxyribose sugar molecules, and nitrogenous bases. If the spirals were split, the DNA could replicate, which explained why genes were transferred from parents to their children. Additionally, the order of compounds on the DNA indicated that there was a unique ‘code’ on each strand. Watson and Crick believed that this ‘code’ was translated into specific proteins. , ,
They’re idea was to show that DNA had to copy itself during the cell division process. The point of this idea was that the DNA molecule make exact replicas of itself in order to pass to its “daughter cells”. Though the two groups were working separately, Watson saw the work that Franklin was doing in her lab, from her images they deduced that DNA might consist of two strands of DNA that were connected and shaped much like a spiral staircase. From seeing the images they decided on a model approach to prove their theory. They designed many variations all to no avail until they stumbled upon the right connects. Discovering that DNA was less like a Spiral staircase and more like a twisted ladder, they finally had the right configuration, a double helix. At this point of their experiment they were only missing one final clue. They needed to know how the different components of DNA bonded together. They found this answer with the help of an American named Jerry Donohue, a chemist who found that hydrogen bonding was the key. The hydrogen allowed the different components to bond together from a position on the inside to the structure and phosphates worked from the outside of the structure. Once all the pieces were discovered, Watson and Crick could finally construct their final product and write their paper. They noted the way DNA was constructed that it spoke of
The first and primary contribution to solving the DNA structure was the relationship of Crick and Watson. Without their teamwork and determination, another scientist would have discovered the structure before them. One of Crick’s bigger contributions was discovering the gene is self-replicating. After talking with John Griffith, Crick came up with the idea that the gene is self-replicating, meaning the gene has the ability “to be exactly copied when the chromosome number doubles during cell division”(126). With further discussion with Griffith, Francis believed that DNA replication involved specific attractive forces between the flat surfaces of the bases (128). One of Watson’s major contributions was after seeing the B form of DNA by Franklin, Watson knew that the structure of DNA was two-chained and that led to the building of the model of DNA (171). Also through research, Watson became aware that adenine and thymine pair together and are held by two hydrogen bonds that were identical in shape to the guanine and cytosine pair held together by at least two hydrogen bonds (194). This discovery showed that the two chains of DNA are complementary to each other. With these individual contributions coming together, Watson and Crick successfully were able to piece together the structure of DNA.
DNA is made up of nucleotides, and a strand of DNA is known as a polynucleotide. A nucleotide is made up of three parts: A phosphate (phosphoric acid), a sugar (Deoxyribose in the case of DNA), and an organic nitrogenous base2 of which there are four. The four bases are as followed: Adenine (A), Cytosine
DNA is continuously evolving as it has developed various aspects of illicit cases, as well as playing vital roles in all cellular systems. The discovery of DNA has impacted and will trigger the fuel of new findings later in the future. DNA does not only significantly affect a cell’s function, but it aids the species to develop and reproduce, despite the altering conditions.
It was in 1984 when Alec Jeffreys, a British geneticist, discovered that specific sequences of DNA did not add to the function of a gene but were still constant throughout it. (Britannica). Jeffreys called these minisatellites and determined that each individual organism had a unique arrangement of minisatellites (Britannica). In the early uses of DNA fingerprinting, it was only used for identifying genetic diseases and disorders but people quickly realized that it could be used in many different areas of science (hubpages). Years after the discovery of DNA fingerprinting, it had been used to solve the first immigration case, the first paternity case, and even helped identify the first identical twins (le.ac.uk). The first methods of DNA fingerprinting were accurate, but you would have had needed to acquire a large amount of DNA. Over time, the advancement of science has led to major advances that formed the basis of DNA profiling techniques. These newer methods are still used today and allow scientist to use skin, blood, semen, and hair to gather DNA (le.ac.uk). In 1988 DNA fingerprinting was used for the first time in a criminal investigation. Timothy Spe...
Crick discovered the structure of DNA in 1953 and others discovered the genetic code a few years after. The old idea of genes as beads on a string, chromosomes, seemed to gain its vindication from the Watson and Crick model. Each of the three nucleotides in the DNA codes for an amino acid , a string of amino acids makes a protein. Many genes are separated by DNA sequences of nucleotides that are not transcribed into RNA. Proteins are coded by partial sequences on two or more chromosomes. Only a small percentage of DNA codes for proteins are higher than the organisms. In humans DNA codes for proteins are only one percent but not higher than two percent. Many of the rest contain sequences that are repeated over and over again.
Each of the nucleotides accommodate a phosphate group, sugar group, and a nitrogen base. There is four nitrogen bases in DNA. The four nitrogen bases are; Adenine (A), Thymine (T), Guanine (G), and Cytosine (C). Each of the bases are connected to a sugar molecule and a phosphate molecule. They are then positioned into two long strands that form a spiral called a double helix (DNA). The nitrogen bases are paired up with one another. Adenine and Thymine will always be paired with each other because of the bonds between them. Between A and T, there are two hydrogen bonds. The same goes with Guanine always being paired with Cytosine due. Between both G and C there is three hydrogen bonds. The nitrogen bases Adenine and Guanine won’t pair up with each other because, of their size. Both the nitrogen bases Adenine and Guanine are a purine base. Thymine and Cytosine are both a pyrimidine base. Adenine pairs with Thymine, and Guanine pairs with Cytosine, because they are of opposite
In the late 1860’s, a Swiss chemist named Friedrich Miescher first identified DNA. It can be said that he successfully completed the first part of the gene puzzle. He found what he called nuclein in the pus he extracted from a surgical bandage. He called it “nuclein” because it was found in the nucleus of the cell. The term “nuclein” was later changed to “nucleic acid” and eventually to “Deoxyribonucleic Acid” or “DNA.” At this point, many scientists did not realize how important this information was, therefore many ignored this information. Then, in 1919, an American biochemist named Phoebus Levene laid the groundwork for the future studies of DNA. He was the first to identify and explain how the nucleic acid components, sugar and phosphate, combine to form nucleotides. Next, Erwin Chargaff, a student of Cambridge, fortified the foundation of studies that had already been made. He created a set of rules called “Chargaff’s rules.” The first rule he established is that, in human DNA, the number of adenine components equals the number of thymine components and the number of guanine components equals the number of cytosine components. The second rule he established was that the form of DNA is different in a human compared to in an animal. He found strong ...
DNA – the very molecule that defines who we are. It is still fascinating that a molecule that is so small that is not visible to the naked eye determines not just our physical appearance but also our mental wellbeing. Over 60 years, the discovery of the double helix DNA had impacted various fields relating to Biology and Chemistry, contributing to the advancement of technology and subsequently mankind too.
DNA (deoxyribonucleic acid) is a self-replicating molecule or material present in nearly all living organisms as the main constituent in chromosomes. It encodes the genetic instructions used in the development and functioning of all known living organisms and many viruses. Simply put, DNA contains the instructions needed for an organism to develop, survive and reproduce. The discovery and use of DNA has seen many changes and made great progress over many years. James Watson was a pioneer molecular biologist who is credited, along with Francis Crick and Maurice Wilkins, with discovering the double helix structure of the DNA molecule. The three won the Nobel Prize in Medicine in 1962 for their work (Bagley, 2013). Scientist use the term “double helix” to describe DNA’s winding, two-stranded chemical structure. This shape looks much like a twisted ladder and gives the DNA the power to pass along biological instructions with great precision.
The Double Helix tells a tale of fierce competition, perseverance, and scientific innovation as we follow James Watson and his cohort Francis Crick on their quest to discover the secret to life, the structure of deoxyribonucleic acid. Although already fascinated with DNA, Watson struggled with finding chemistry exciting enough to learn it in depth. He had studied birds in college and thereby managed to avoid any formal chemistry or physics courses. As he later pursued a PhD in biochemistry, he realized he could put it off no longer and attempted to learn organic chemistry at Indiana University. However, after a mishap in the lab, he was encouraged instead to study nucleic acid chemistry with Herman Kalckar in Copenhagen. There, his mind strayed from his work and he began doing unauthorized research in the lab of Ole Maaløe, studying phages. Herman stopped teaching Watson after going through a divorce with his wife, and sent Watson off to a scientific conference in Naples. Although he was bored by many of the lectures, Maurice Wilkins’s talk about X-ray diffraction fascinated Watson. He was struck by an X-ray diffraction picture of DNA that Maurice presented and was determined to study the acid. He later got to know more about Maurice’s colleague, Rosalind Franklin, who was proud, stubborn, and very difficult to work with. Watson greatly admired the lecture given by the renowned Linus Pauling, who had discovered the structure of the alpha-helix and was thought of as the leader in DNA research in the scientific world.
...f the structure of DNA by James Watson and Francis Crick in 1953 that was extremely influential for future researchers. They determined that DNA was a double helix structure composed of base pairings, with a sugar phosphate backbone. This model explained how “genes can duplicate themselves [and] would eventually lead to our current understanding of many things, from genetic disease to genetic engineering” (Salem).