-
Discovery of Nucleic Acids - Friedrich Miescher
Friedrich Miescher discovered DNA itself through his studying of white blood cells when after the experiment there’s was snotty gray stuff of biological substance he called nucleic but didn’t know it’s role or what it look like -
Period: to
History of the DNA
-
Levene's Tetranucleotide
Levene proposed that there were four nucleotides per molecule.
Said DNA could not store the genetic code because it was chemically far too simple -
Frederick Griffith and his Transformation Experiment
Studied the epidemiology and pathology of 2 strains of Streptococcus pneumoniae. In January 1928 reported the first widely accepted demonstrations of bacterial transformation. Griffith used two strains of Streptococcus:
Type S: virulent (deadly)
Type R: non-virulent (harmless)
Observed bacterial transformation but did not understand the mechanism -
Component of the DNA - Phoebus Levene
Determined the components of DNA:
adenine, guanine, thymine, cytosine, deoxyribose phosphate.He Also fined phosphate-sugar-base units called nucleotides, (1869-1940) -
Avery, MacLeod and McCarty
Studies on the Chemical Nature of the Substance Inducing Transformation of Pneumococcal Types: Induction of Transformation by a Deoxyribonucleic Acid Fraction Isolated from Pneumococcus Type III
DNA not protein was responsible for the bacterial transformation Griffith observed! -
Studies on the Chemical Nature
On February, 1944, studies on the Chemical Nature of the Substance Inducing Transformation of Pneumococcal Types: Induction of Transformation by a Deoxyribonucleic Acid Fraction Isolated from Pneumococcus Type III
DNA not protein was responsible for the bacterial transformation Griffith observed! -
1951 James Watson and Francis Crick
In 1951, ames Watson and Francis Crick proposed a double helix structure for DNA, which was later found to be incorrect. Rosalind Franklin's work revealed the nucleobases were located in the center of the molecule. This allowed Watson and Crick to revise their model and gain a better understanding of genetic information storage and transmission. Their discovery remains important in molecular biology and is still studied today. -
Hershey-Chase Experiments (1952)
Used phages and radiolabeled phosphorus and sulfur
Hershey and Chase concluded that DNA, not protein, was the genetic material.
A protective protein coat was formed around the bacteriophage, but the internal DNA is what conferred its ability to produce progeny inside bacteria -
Erwin Chargoff was Counting Nucleobasesm (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!!! -
Triple Helix (1952)
In 1953, Linus Pauling and Robert Corey made a groundbreaking proposal in the field of molecular biology - they suggested that DNA, the genetic material of living organisms, had a triple helix structure. This theory was in direct contrast to the existing understanding of DNA, which held that it had a double helix structure.
Pauling and Corey based their hypothesis on their extensive knowledge of the chemical properties of molecules, and they used X-ray crystallography to support their claims. -
Rosalind Franklin photo 51
Rosalind Franklin's famous photograph "Photo 51" is an X-ray diffraction image of DNA that was taken in 1952. The image provided crucial information about the structure of DNA, which was later used by James Watson and Francis Crick to propose the double helix model of DNA. Although Franklin did not receive full credit for her contribution to the discovery, her photograph remains an important milestone in the history of molecular biology. -
Francis Crick, James Watson, Maurice Wilkins, and Rosalind Franklin
Francis Crick, James Watson, Maurice Wilkins, and Rosalind Franklin were all key contributors to the discovery of DNA's double helix structure. On April 25, 1953, three papers were published in Nature that described the structure of DNA. Watson and Crick wrote the first paper, while Wilkins and Franklin authored the second and third papers, respectively. These publications were a major milestone in molecular biology and laid the foundation for future research in genetics.