Who was the first person to discover DNA?
James Dewey Watson (1928–): Co-discoverer of the structure of DNA
What was the first attempt at cracking the structure of DNA?
Following the seminar, Watson and Crick presented their first attempt at cracking the structure of DNA – a helix with the phosphate and sugar backbone inside of the helix. Franklin, however, saw a flaw in their model. She understood that the hydrophilic phosphate and sugar backbones of the nucleotide chains should be positioned outside of the molecule so as to interact with water, and the hydrophobic bases should be on the interior. The head of the Cavendish laboratory, Sir Lawrence Bragg, was embarrassed by Watson and Crick’s blunder and put a halt to their work. Fortunately, a series of events caused Bragg to change his mind. Franklin was leaving Wilkins’ lab for another post, and it was unclear who would take her place in DNA research. Meanwhile, Linus Pauling was hot on the trail in the race to decipher DNA structure. He had proposed a model for DNA in early 1953, although the model incorrectly contained three helices. Since he and Pauling were bitter rivals, Bragg permitted Watson and Crick to resume their DNA work. Crick’s advisor, Max Perutz, allowed him to read a summary report of Franklin’s data. Although Watson had seen the same data back in 1951, when he had attended Franklin’s lecture at King’s College, he lacked the background in X-ray crystallography necessary to interpret Franklin’s data. With Crick’s background in X-ray diffraction, he understood the data as providing evidence for a double helix (’twisted ladder’ configuration), with two nucleotide chains running in opposite directions.
What is the name of the scientific paper that Watson and Crick published in 1953?
Their hypothesis of DNA structure was published in the journal Naturein 1953. The title by Watson and Crick was modest: ’Molecular structure of nucleic acids: A structure for deoxyribose nucleic acid’, barely suggesting that they had solved a secret of life. For their momentous finding, they shared the 1962 Nobel Prize with Wilkins.
What did Watson do after the discovery of the human genome?
Under his leadership, CSHL rose to its current status as a world-class institute of science in tackling cancer, neurological disease and other causes of human suffering. In 1989, he was appointed to head the Human Genome Project at the National Institutes of Health, but left in 1992 due to conflict with Dr Bernadine Healy, its new director. Watson had opposed attempts to patent gene sequences, which he believed were not subject to ownership because they were ’laws of nature’. Watson also published the fully sequenced human genome online after it was presented to him on 31 May 2007 and authored The Double Helix, which became one of Modern Library’s 100 best non-fiction books. In addition to countless honorary degrees and awards, he also wrote the classic textbook, Molecular Biology of the Gene.
Who were the key players in the DNA story?
The key players in the DNA story were Watson, Crick, Maurice Wilkins, Rosalind Franklin and Linus Pauling. Wilkins was the first investigator to take on the study of DNA and had been working painstakingly for years at King’s College in London, United Kingdom. Franklin was a postdoctoral fellow in Wilkins’ lab. Her data and insights were crucial for disproving Watson and Crick’s first DNA model proposed in 1951 and informing their revised model. Finally, Linus Pauling, the great American chemist, was portrayed in Watson’s book as their greatest competitor, and some believed he would have beaten Watson and Crick to their conclusion if he had had access to Franklin’s data.
Who wrote the book The Double Helix?
Watson JD. The Double Helix:A Personal Account of the Discovery of the Structure of DNA.1st paperback ed. New York: Atheneum; 1980. [Google Scholar]
Did Watson and Crick see Franklin's report?
It is debatable whether Watson and Crick should have seen Franklin’s summary report without her permission. In Watson’s book, The Double Helix, he admits that he and Crick obtained Franklin’s data from her progress report to the Medical Research Council in 1952 and that she was not aware of it. Ethics aside, the pieces of the puzzle were rapidly falling into place. Franklin’s X-ray diffraction data suggested to Crick the double helical form of the DNA molecule. Thanks again to Franklin, the investigators also now believed that the sugar-phosphate backbone was oriented on the outside, and the base pairs on the inside, of the double helix. The correct structures of the bases were revealed to them by an American chemist named Jerry Donohue, who just happened to share an adjoining office. The bases came in four flavours: adenine, guanine, thymine and cytosine, or A, G, T and C for short. Adenine and guanine shared a similar structure and were called purines, while thymine and cytosine were also similar and were called pyrimidines. Then, in 1952, Erwin Chargaff visited England and alerted them to the fact that in his experiments on DNA extracts, the ratios of A to T and G to C were near unity. In contrast, the amounts of other combinations of the bases were highly variable. To Watson and Crick, this finding – known as Chargaff’s ratios – suggested a consistent pairing of the bases (A-T and G-C). Even more importantly, this pairing feature explained how a molecule of DNA could replicate itself, a feature that was crucial for any molecule designed to copy genetic information from cell to cell and from organism to organism. In their landmark paper, they wrote, “It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material.”
When was the sequencing of DNA completed?
With Fred Sanger and colleagues’ publication 16 of an efficient method for sequencing DNA in 1977, the way was open for the complete reading of the genetic information in any species. The task was completed for the human genome by 2003, another milestone in the history of DNA.
Which scientist discovered that DNA has the same amount of guanine as cytosine?
This explained biochemist Erwin Chargaff ’s discovery that the DNA of any species has the same amount of guanine as of cytosine, and of adenine as of thymine 6. It also showed that each DNA chain in a helix provides a perfect template for the other, reading the base sequence in opposite directions.
What is the shape of guanine bonded to cytosine?
Once Watson had made cutouts of the alternative keto isomers, he had the blinding revelation that when guanine bonded to cytosine, it made an identical shape to that of adenine bonded to thymine, and that the shapes fitted perfectly into the helical frame provided by the backbones of each DNA chain.
What was the key to the gene?
He was convinced that the nature of the gene was the key problem in biology, and that the key to the gene was DNA. The Cavendish was a physics lab, but also housed the Medical Research Council’s Unit for Research on the Molecular Structure of Biological Systems, headed by chemist Max Perutz.
Why was everyone interested in the structure of proteins back in the 30s?
Everybody was interested in the structure of proteins back in the 30s because nobody thought that DNA could possibly be complicated enough to be the molecule of life. That wasn’t really discovered until the mid-40s and then, obviously, it became very important to study its structure.
When did Watson and Wilkins combine their theory?
In late 1951 , he and Watson combined that theory with what they knew about the chemistry of DNA, and what they remembered of talks given by Wilkins and Franklin, to build a model of the DNA structure. They got it badly wrong: Wilkins and Franklin quickly demolished it.
When did X-ray crystallography start?
At the time, X-ray crystallography of large molecules – the sort of molecules that you get in living bodies – was still a very, very small field. It had really started in the 1930s. Everybody was interested in the structure of proteins back in the 30s because nobody thought that DNA could possibly be complicated enough to be the molecule of life. That wasn’t really discovered until the mid-40s and then, obviously, it became very important to study its structure.
When was DNA discovered?
The double helix structure of DNA was first discovered in 1953 by James Watson, Francis Crick, and Rosalind Franklin. DNA molecules are found in the nucleus and store the genetic code; that is, all the information required for an organism to function. What is the structure of DNA?
What was the first image of DNA?
Franklin was an expert in an imaging technique called X-ray crystallography, which she used to produce the first ever image of the helical shape of DNA. Watson and Crick were awarded the Nobel Prize for their work in 1962.
What is the Structure of DNA?
DNA molecules are polymers, which means they are large molecules made up of many smaller molecules. The small molecules that make up DNA are called nucleotides. Each nucleotide contains a phosphate group, a sugar molecule (called deoxyribose ), and a nitrogenous base.
What is DNA Replication?
DNA replication is a process in which two identical DNA replicas are produced from a single DNA molecule. It is an essential part of cell division, which is necessary for the growth and repair of damaged tissues.
How are DNA and RNA similar?
DNA and RNA are very similar molecules. Both are types of nucleic acid, both contain genetic information, and both can be found in the nuclei of cells. The structure of RNA nucleotides are also similar to those of DNA; both contain a phosphate group, a sugar molecule, and a nitrogenous base.
What is the difference between DNA and RNA?
Whereas DNA contains deoxyribose, RNA contains a different type of sugar molecule, called ribose.
What is DNA made of?
DNA molecules are polymers and are made up of many smaller molecules, called nucleotides. Each nucleotide contains a phosphate group, a sugar molecule, and a nitrogenous base.
When did DNA become the defining unit of heredity?
However, it wasn't until 1944 that deoxyribonucleic acid (DNA) was identified as the 'transforming principle' .
Who discovered the nucleus?
Friedrich Miescher identifies "nuclein". In 1869, Swiss physiological chemist Friedrich Miescher first identified what he called "nuclein" in the nuclei of human white blood cells, which we know today as deoxyribonucleic acid (DNA).
What is epigenetics in biology?
Essentially, the term epigenetics means 'on genetics' and refers to the biological markers which influence what 'comes out' of the DNA sequence. Image by Wikimedia Commons.
What did Mendel discover about pea plants?
He identified seven characteristics: plant height, pod shape and colour, seed shape and colour , and flower position and colour.
Why is mapping the human genome important?
Many organisations had a long-standing interest in mapping the human genome for the sake of advancing medicine, but also for purposes such as the detection of mutations that nuclear radiation might cause.
How many base pairs are in the human genome?
In 2001, the Human Genome Project had published a 'rough draft' of the human genome, which included a 90% sequence of all three billion base pairs .
How many genes are in a fruit fly?
During their research, the scientists discovered that every fruit fly cell contains 13,601 genes, making it by far the most complex organism decoded at the time. However, by contrast, human cells contain 70,000 genes. Whilst the Human Genome Project still had a long way to go to achieve its ultimate objective, this was an important milestone along the way.
When did Astbury use the images to propose a structure for DNA?
In 1938 , Astbury used the images to propose a structure for DNA in which the bases are stacked on top of each other, but the pictures weren’t detailed enough for him to get much further.
What is DNA made of?
He also discovered that DNA is made up of units that he called nucleotides. Each of these is made up of a sugar, phosphate group and base, and they are linked by bonds between the phosphate groups of one nucleotide and the sugar of the next, forming a so-called backbone. But this was as far as his correct findings went.
What were the names of the bases in DNA?
Working under Hoppe-Seyler in the late 1800s, he discovered DNA’s ‘bases’ (the chemical opposite of acids) and named them thymine (T), adenine (A), cytosine (C) and guanine (G).
How many nucleotides are in a DNA molecule?
He thought that each DNA molecule contained only four nucleotides, one with each type of base, linked together in a ringhe called a ‘tetranucleotide’. Levene’s tetranucleotides were too simple to carry a genetic code, and so reinforced the idea that proteins must be the hereditary agent.
What are some interesting facts about DNA?
Read more about DNA: 1 Instant Genius: DNA 2 The origin of life 3 A genetic mutation could help us understand how to stop pain 4 Growing up poor can affect your DNA as well as your health
What is Friedrich Miescher's lab?
The lab studies the composition of cells, and Friedrich Miescher is analysing relatively simple white blood cells, which he extracts from the pus in a local clinic’s discarded bandages. Having exhausted his efforts in classifying the cell’s proteins, Miescher turns his attention to another substance that keeps appearing in his samples.
How do you study crystals?
This is the study of the structure of crystals by firing X-rays at them. The X-rays bounce off the regular arrangements of atoms in crystals, and the patterns they make are captured on film. An equation is then used to work out the crystal’s structure.
