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
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
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
Huether, S.E. & McCance, K.L. (2008). Understanding pathophysiology (4th ed.). St. Philadelphia, PA: Mosby Elsevier
Deoxyribo Nucleic Acid (DNA) is a chromosome found in the nucleus of a cell, which is a double-stranded helix (similar to a twisted ladder). DNA is made up of four bases called adenine (A), thymine (T), guanine (G), and cytosine (C), that is always based in pairs of A with T and G with C. The four bases of A, C, G, and T were discovered by Phoebus Levene in 1929, which linked it to the string of nucleotide units through phosphate-sugar-base (groups). As mention in Ananya Mandal research paper, Levene thought the chain connection with the bases is repeated in a fix order that make up the DNA molecu...
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.
Chemistry dictates the structure of DNA. DNA is a polymer of monomers called nucleic acids. These are made of a nitrogenous base, a phosphate group and a sugar. It is the negative charge on the phosphate group that makes DNA an acid. There are 4 different bases: adenine, thymine, guanine and cytosine. In groups of three, these four bases can code for any protein coded for in an organism’s genome. Two strands of nucleic acids stack on top of each other in a double helix. The backbone of the nucleic acids consists of the interaction between phosphate groups and the hydroxide groups of nucleic acids. These are held together by covalent bonds called phosphodiester bonds. The helix itself is held together by hydrogen bonds. Although h...
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...
Deoxyribonucleic acid (DNA) is an acclaimed extraordinary discovery that has contributed great benefits in several fields throughout the world. DNA evidence is accounted for in the majority of cases presented in the criminal justice system. It is known as our very own unique genetic fingerprint; “a chromosome molecule which carries genetic coding unique to each person with the only exception of identical twins (that is why it is also called 'DNA fingerprinting ')” (Duhaime, n.d.). DNA is found in the nuclei of cells of nearly all living things.
Cain, M. L., Urry, L. A., & Reece, J. B. (2010). Campbell Biology. Benjamin Cummings.
"The discovery of the structure by Crick and Watson, with all its biological implications, has been one of the major scientific events of this century." (Bragg, The Double Helix, p1) In the story of The Double Helix, James Watson tells of the road that led to the discovery of life's basic building block-DNA. This autobiography gives insight into science and the workings within a professional research laboratory that few members of society will ever be able to experience. It also gives the reader an idea of the reality of life for one scientist and how he struggled with the problem of DNA. However, the author's style is marked by his lack of objectivity and inclusion of many biased opinions and personal prejudices.
Hoehn, K. & Marieb, E. N. (2007). Human Anatomy & Physiology, Seventh Ed. San Francisco, CA: Pearson Education, Inc.
Firstly, in order to compresence the complexity of our debate, we have to take in mind the definition of nature and nurture. Yes, is true that some of our characteristics are inherited by our ancestors, most of our physical characteristics, such as hair color and type; the pigmentation of our skin, those are a product of our genes thus our DNA (Jewel, 2007).
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.
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.