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Discovery of nucleo acids
Friedrich Miescher that was an swiss physican/biologist, in 1869 disovered the nucleic acids. He isolated the genetic material form white blood cell nuclei and noted it had an acidi nature and callet it nuclein. -
Discovery the DNA components
Phoebus Levene determinated the components of DNA:
-adenine, guanine, thymine, cytosine, deoxyribose phosphate.
-Defined phosphate-sugar-base units called nucleotoides. -
Levane's Tetranucleotide
The main idea oh Levene was that there were 4 nucleotides per molecule. In contrast, he thoughted that DNA could not store the genetic code becasue it was chemically far too simple. -
Frederick Griffith
Studied the epidemiology and pathology of 2 strains of Streptococcus pneumoniae.
In january 1928 reported the first widely accepted demonstrations of bacterials trasnformation. -
Griffith's Transformation Experiment
This experiment was performed using two strains of Streptococcus pneumoniae, a bacterium that causes pneumonia.One of the strains was virulent, meaning it was able to cause disease, while the other was non-virulent. When Griffith mixed the two strains together and injected the mixture into mice, he found that the mice developed pneumonia and died. Upon examination of the bacteria from the infected mice, Griffith found that the non-virulent strain had been transformed into the virulent strain. -
Avery, MacLeod and McCarty
Oswald Avery, Colin MacLeod, and Maclyn McCarty were three scientists who performed a series of experiments in the 1940s that helped to confirm that DNA is the genetic material.They conducted a series of experiments using a strain of Streptococcus pneumoniae and purified different components of the bacterium, including DNA, RNA, and protein, to determine which component was responsible for the transfer of genetic information. -
Double helix
Watson and Crick's discovery of the double helix structure of DNA revolutionized our understanding of genetics and biochemistry. Prior to their discovery, scientists believed that DNA was a simple linear molecule, but Watson and Crick's research showed that it was a complex, double-stranded molecule that could store and transmit genetic information. But later this idea was denied. -
Erwin Chargraff
Chargaff began his research on DNA in the 1940s and was one of the first scientists to isolate and analyze DNA from various species. He used a technique known as chromatography to separate and quantify the different components of DNA. Through his experiments, he discovered that the amount of adenine in DNA always matched the amount of thymine, and the amount of cytosine always matched the amount of guanine. -
Chargaff rules
The rules state that:
In any given DNA sample, the amount of adenine (A) is equal to the amount of thymine (T).
In any given DNA sample, the amount of cytosine (C) is equal to the amount of guanine (G).
These rules helped to establish the concept of complementary base pairing in DNA and played a crucial role in the discovery of the structure of DNA by James Watson and Francis Crick. The rules also led to a deeper understanding of the nature of genetic information and the way it is encoded in DNA -
Hershey-Chase Experiment
The Hershey-Chase experiments were a series of experiments conducted by American virologists Alfred Hershey and Martha Chase in 1952. These experiments helped to establish the fundamental nature of the genetic material in viruses and to confirm that DNA, and not protein, is the genetic material of life. -
Hershey-Chase results
The results showed that the radioactive phosphorus was found in the newly formed phages within the infected bacteria, while the radioactive sulfur was not. This provided strong evidence that the genetic material of the virus was DNA and not protein. The experiments demonstrated that DNA, and not protein, is the genetic material of life, a finding that helped to establish the central role of DNA in the transmission of genetic information. -
Double Helix?
Watson and Crick's discovery of the double helix structure of DNA revolutionized our understanding of genetics and biochemistry. Prior to their discovery, scientists believed that DNA was a simple linear molecule, but Watson and Crick's research showed that it was a complex, double-stranded molecule that could store and transmit genetic information. -
Triple Helix?
Linus Pauling and Robert Corey proposed a triple helix structure for DNA. But it was proven wrong, what they probably saw were the two helix but not clearly so they thought there was a third one. -
Actual structure, Noble Prize and Rosalind Franklin
Rosalind took photo 51 of the actual structure of DNA that proved that there were just two helix but placed in the oposite way that Watson and Crick thought. Wilkins took the picture from Rosalind and gave it to them so they could publish it and get the credit as well as finish their papers. The three of them; Watson, Crick and Wilkins, got the Noble prize. Rosalind didn't get it because she was already dead but none of them gave her any credit for all the research she did.