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Discovery of Nucleic Acids
The discovery of nucleic acids was a major milestone in biology. Swiss chemist Friedrich Miescher first isolated "nuclein" from white blood cells in 1869. He was born in 1844 in swidden, and he died in 1895 in swidden. He studied at Basilea University. Also, he isolated the genetic material that come from the white blood cell nuclei in 1869. Furthermore, he noted it had an acidic nature, and he called it nuclein with this he prepared a way to identify them as the bearing from the DNA. -
Discovery of DNA Components
He identified the three primary components of DNA. He named these components as nucleotides, which consist of a sugar molecule, a phosphate group, and a nitrogenous base. Levene's work led to a better understanding of the basic structure and composition of DNA, and provided a foundation for future research on the molecular structure of genetic material. -
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 Part 1
Frederick Griffith's transformation experiment in 1928 demonstrated that genetic material could be transferred between bacteria. He observed that a harmless strain of Streptococcus pneumoniae bacteria could be transformed into a virulent, disease-causing strain when mixed with heat-killed virulent strains. The transferred material was found to be heritable and capable of passing on the virulent properties to subsequent generations of bacteria. -
Frederick Griffith and his Transformation Experiment Part 2
This transformation phenomenon provided early evidence for the existence of DNA as the genetic material and paved the way for further research on the structure and function of DNA. Griffith's work was a major milestone in the history of molecular biology and genetics and had far-reaching implications for medicine and biotechnology. -
Griffith's experiment explanation
Determined the cause of the transformation in Griffith's
They took live R and heat-treated S and mixed it with one of two enzymes:
A protease (destroys protein)
A DNAse (destroys DNA) 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! -
Counting Nucleobases
Erwin Chargaff, an Austrian biochemist, used paper chromatography and UV spectroscopy to examine the abundance of nucleobases and noticed something odd. It came to be known as "Chargoff's Rules"
Amounts of Adenine = Amounts of Thymine
Amounts of Cytosine = Amounts of Guanine
This always happened in every single species. -
Hershey-Chase Experiments
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. -
Pualing's Triple Helix
Proposed the idea of a triple helix DNA structure before the discovery of the double helix. He suggested that DNA could form a triple-stranded helix with a backbone made up of three intertwined chains of nucleotides. Each chain would be held together by hydrogen bonds between the nucleotides. Suggested that this structure could be involved in genetic information storage and transmission.
Later on, this structure was demonstrated wrong. -
DNA with Double Helix Part 1
Francis Crick, James Watson, Maurice Wilkins they were working at the Cavendish labs in Cambridge and Rosalind Franklin at King's college in London. Rosalind took a lot of amazing photographs of the B form of DNA, she figures out how to see the wet form which is the form that exists in cells. He took a photo that showed very clearly the X in the middle which is a sign of a double helix Rosalind was not prepared to publish this until she had finished all the calculations, -
DNA with a Double Helix Part 2
but Maurice Wilkins get the photo and manage to get it to Watson and creek in Cambridge, when they see the image they know exactly what it means their model from 1951 was backwards the model based on Rosalind's image, and also we have the paper that exactly describes how DNA looks like. So Watson and Crick's Model was the correct one. So with this, we know that DNA is a double-stranded Helix made of sugar and phosphate groups running anti-parallel.