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Discovery of Nucleic Acids
Nucleic acids were discovered in 1869, when the Swiss Friedrich Miescher, that is a Scientific, at the age of 24 years old, isolated the genetic material from white blood cell nuclei. He noted it had an acidic nature and called it nuclein. -
Phobeus levene
Levene was a really famous biologist and russian-american medic that he studied the structure and the function of the nucleic acids. He found the DNA that adenine, guanine, thymine, cytosine, deoxyribose, and a phosphate group contained.
He thought that there were 4 nucleotides per molecule and also that DNA couldn't store the genetic code because it was chemically far too simple. A really important discovery from him is that he defined phostphate-sugar-base units called nutreotides. -
Frederic Griffith
A British scientist, Frederick Griffith, tried to figure out how bacteria made people sick by performing an experiment of injecting a mice with the disease-causing strain of bacteria. This resulted the mice to develop pneumonia and die. But when he injected the mice with harmless strain, the mice didn't get sick at all. To find out, he took heat-killed bateria and injected it into the mice, causing it to survive, which proved that the reason for pneumonia was not from bacteria. -
Frederick Griffith transformation
In Griffith's next experiment, he mixed heat-killed bacteria with live, harmless ones and injected the mixture into the mice. It was thought that the mice stayed neutral but instead, the mice developed pneumonia and died. Examing the lungs of the mice, he found that it was filled with diease-causing bacteria rather than harmless ones. Somehow, thw heat-killed bacteria had passed their disease-causing ability to the harmless strain. Griffith called this transformation. -
Frederick Griffith hipotesis
Frederick Griffith hypthesized that when the live, harmless bacteria and the heat-killed bacteria were mixed, some factor was transferred from the heat-killed cells into the live ones. That factor, which was thought to be gene, must contain information that could transform a harmless bacteria into a disease-causing bacteria. -
Oswald Avery
Together with his collaborator Maclyn McCarty, he discovered that DNA (deoxyribonucleic acid) is the material from which genes and chromosomes are made and how they define human sexuality. Previously it was believed that proteins were the carriers of genes. -
Erwin Chargaff
Chargaff discovered two rules that helped discover the double helix of DNA, he also analyzed the nitrogenous bases of DNA in different forms of life, concluding that the amount of purines were not always in equal proportions to those of pyrimidines, the proportion was the same in all cells of individuals of a given species, but varied from species to species. -
Rosalind Franklin
Before Watson and Crick, Franklin arose with her knowledge of the structure of DNA. While working with college students, she used x-ray diffraction to find more information about the structure DNA. To perform this technique, Franklin had to purify the DNA first, stretch the DNA into thin fibers inside a tube, and then shoot an x-ray beam through the tube to study the findings. After studying the tube, Franklin concluded that DNA was X-shaped or the shape of a helix. -
DNA Discovery
Erwin Chargaff was Counting Nucleobasesm in 1952
Used paper chromatography and UV spectroscopy to examine the abundance of the nucleobases and he started to notice something VERY odd...
Came to be known as "Chargoff's Rules"
Amounts of Adenine = Amounts of Thymine
Amounts of Cytosine = Amounts of Guanine
ALWAYS in EVERY SPECIES!!! -
Martha Chase and Alfred Hershey
They conducted a series of experiments to confirm whether DNA is the basis of genetic material (and not proteins), in what was called the Hershey and Chase experiment. Hershey and Chase found that S-35 lies outside the cell, while P-32 was found inside, indicating that DNA was the physical carrier of hereditary material. S-35 and P-32 are radioactive isotopes. -
Photo 51
Photo 51 is an X-ray based fiber diffraction image of a paracrystalline gel composed of DNA fiber taken by Raymond Gosling, a graduate student working under the supervision of Rosalind Franklin in May 1952 at King's College London, while working in Sir John Randall's group. The image was tagged "photo 51" because it was the 51st diffraction photograph that Franklin and Gosling had taken. It was critical evidence in identifying the structure of DNA. -
James Watson & Francis Crick
Watson and Crick wished to gain knowledge on DNA structure. The two used Franklin’s x-ray to build a model of DNA that was composed of cardboard and wire. Using the model and previous information, it was discovered that DNA was a double helix and the nucleotides were bonded together with hydrogen bonds. Also, the scientists studied complementary base pairing, which added validity to Chargaff’s rule. To summarize, Watson and Crick validated the information from scientists about DNA was true. -
Double Helix
Francis Crick and James Watson were the first people too figure out the double helix structure of DNA. DNA is full of nucleotides, and are made of three parts: a phosphate group linked to a deoxyribose sugar,and turned linked to one of four nitrogenous bases adenine (A), cytosine (C), guanine (G), or thymine (T). Nucleotides are linked in series into a chain, with phosphate and sugar groups alternating. -
Triple Helix
Scientist Pauling told the world the triple-stranded helix. hypothesis. He said it looks the same as a regular DNA strand but has three oligonucleotides wind around each other and form a triple helix. But others said no such thing can exist. -
Linus Pauling
Pauling developed the theory of the molecular clock, which enables one to judge the separation in time between two species by looking at the number of differences in their hemoglobin proteins. -
The genetic code
Scientist Marshall Nirenburg and Har Khorana, cracked the genetic code with their cooperation..They successeded by matching amino acids to synthetic triplet nucleotides.