Sahana KanabarScience 10B25th February 2015

DNA and its Discovery

Our cells contain the double helix formation of deoxyribonucleic acid (DNA), which hold chromosomes with all of our genetic information. Even before the discovery of DNA familial resemblance and distribution of traits or defects always showed a connection between generations. Even farmers knew enough about genes to breed their best animals to keep the most desirable traits, either for sale or consumption. Advances in the scientific knowledge of DNA have only really taken off over the past century but it has revolutionized the pharmaceutical and agriculture industries.

For many years DNA remained evasive so it was only possible to study the traits that came through. The first genetics experiment discovered the fundamental laws of inheritance. Moravian monk Gregor Mendel pioneered the study in the 1863, with an experiment that took eight years. He determined the Law of Segregation, the Law of Independent Assortment, and the Law of Dominance along with deducting that genes came in pairs and were inherited as distinct units from parents. As BBC Science so eloquently put it, He cultivated nearly 30,000 pea plants, carefully analysing seed and plant characteristics. By following certain traits through the generations, he realised that some traits appeared to be dominant while others would be recessive and fail to show when certain pea plants where crossed (qtd. in Mendels Peas). This was a breakthrough in genetics but it went unappreciated in Mendels time.

The history of DNA is quite an interesting one although it has been somewhat riddled with controversy regarding the credit and identification of the key individuals who discovered DNA (Murnaghan. History of DNA: The Early Days. December 2012). James D. Watson and Francis Crick are generally accredited with the discovery of DNAs molecular structure. Significant contributions made by other scientists are often marginalized although different scientific work enabled such a breakthrough discovery. In 1962 Watson, Crick, and Maurice Wilkins received the Nobel Prize in Physiology or Medicine. Wilkins worked with Rosalind Franklin on X-ray crystallography work in the early 1950s, which contributed to Watson and Cricks derivation of the double helix. Franklin died four years before the prize was given, allowing her part to go ignored for a long time. Even earlier than that Erwin Chargaff discovered the base pairs that create the double helix formation, adenine is always paired with thymine while guanine is paired with cytosine. He was unable to figure out DNAs formation but pioneered work in the development of proteins.

DNA is commonly used in forensics to help solve crimes. Hair, blood, and skin cells can be picked up at the crime site and matched to a persons specific DNA sequence. The first cases of collecting DNA evidence started in the 1980s and by the early 1990s started becoming more widely used in laboratories. In the 1990s DNA was also used to dispute paternity cases and to establish a familial link in immigration or adoption cases. Now databases are being filled with individuals genetic information, making it even easier to use different methods to verify someones identity. Cloning has even become a possibility. In 1996 a sheep, Dolly, became the first mammal to be cloned from an adult somatic[footnoteRef:1] cell using the process of nuclear transfer. While this was a major advance cloning more often happens at a stem cell level. [1: Soma refers to the parts of the organism other than the reproductive cells.]

Fingerprinting was first used in the 1930s by detectives and police labs. Although that is a common use, DNA fingerprinting has many more possibilities. It can be used to diagnose inherited disorders in both prenatal and newborn babies, including cystic fibrosis and thalassemia. Earlier diagnosis allows families to receive proper treatment and learn about managing the disorder. Fingerprinting DNA is contained in every tissue of the body, making it one of the most superior methods of identification. New forensic products are being developed that allow law enforcement to create profiles of criminals based on DNA. Some traits are hard to determine because of the widespread influence of various genes. On the other hand, eye and hair color have proved relatively easy to ascertain from DNA samples, Dr. Kayser said, because a single gene has a large influence on these traits (The New York Times).

Together, our genes are collectively referred to our genome. The goal of the Human Genome Project was to create a detailed map of the human genome. Automation of DNA sequencing became possible in the 1980s, making this seem like the next logical step. It was started in 1990 and completed in 2002. The locations of around 30,000 human genes within our genome were revealed. However, some scientists suggest that the number contained within our body is closer to 70,000. We are nowhere close to discovering all the secrets our DNA holds but good progress is being made.

DateWhat is says

8000 BCLong before the discovery of DNA, early farmers were using selective breeding to improve their crops and livestock. They kept back the best seed and offspring from their farms to begin the next generation.

1859Charles Darwin publishes his theory of evolution through natural selection. It was only long after his death that his ideas finally became widely accepted.

1863Gregor Mendel, an Austria monk, first documents hereditary traits in garden peas.

1953James Watson and Francis Crick accurately describe the molecular structure of DNA as a double helix.

1966The genetic code is revealed. It is established that a sequence of three nucleotide bases corresponds to each of 20 amino acids in the production of proteins. Since then a further two amino acids have been discovered.

1972The DNA composition of humans is found to be 99% similar to chimpanzees and gorillas.

1990The Human Genome Project is launched an international collaborative effort to sequence the entire human genome.

2002The Human Genome Project is completed revealing the location of around 30,000 human genes. The number, however, is currently being debated by scientists who suggest the number is closer to 70,000.

Works Cited:

"An Overview of the Human Genome Project."Genome.gov. National Institutes of Health, 8 Nov. 2012. Web. 16 Feb. 2015.

Betsch, David F. "DNA Fingerprinting in Human Health and Society."Access Excellence. National Health Museum, June 1994. Web. 16 Feb. 2015.

"DNA History Project."ExploreBio. Tangient LLC, 2011. Web. 16 Feb. 2015.

Ferguson, Gillian K. "Mendel's Peas."Mendel's Peas. The Human Genome: Poems on the Book of Life, n.d. Web. 16 Feb. 2015.

Lange, Karen E. "Tales from the Bog."National Geographic. National Geographic Society, Sept. 2007. Web. 16 Feb. 2015.

Pollack, Andrew. "Building a Face, and a Case, on DNA."The New York Times. The New York Times, 23 Feb. 2015. Web. 24 Feb. 2015.

Pray, Leslie A. "Discovery of DNA Structure and Function: Watson and Crick."Nature.com. Nature Publishing Group, 2008. Web. 16 Feb. 2015.

"The Discovery of DNA."BBC GCSE Bitesize. BBC, 2014. Web. 16 Feb. 2015.