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Transcript

Pre 1920:

Fun Fact! Before all of this research and 1950 people thought that genes were like beads on a string.

  • 1869: Doctor Friedrich Miescher isolated the first extract of DNA.
  • 1944: Oswald Avery did an experiment where he transfered characteristics from one strand of DNA to another showing that DNA carries hereditary information.

Early 1950s:

1952:

Late 1950s:

1955:

  • Erwin Chargaff found that there were constant quantities of nucleotides in DNA. They were constant in the same species but not in different species. Examples: Adenine=Thymine & Guanine=Cytosine
  • Rosalind Franklin realized that DNA was a helix through x-ray diffraction.
  • Francis Crick realized there must be a way or system (Messenger RNA/ Central Dogma) to get DNA to transfer to RNA. RNA is a copy of DNA.
  • Paul Zamecnik and Mahlon Hoagland found that if they added RNA to an e. coli that was cell-free it stimulated amino acid incorporation into a protein. This means essentially that they found that the template RNA was stimulating protein synthesis cell-free.

  • 1957: Matthew Meselson and Frank Stahl proved DNA replicated semi-conservatively which means that two strands separate, but stay single stranded and become grouped with another new strand at each generation.
  • 1957-...: Arthur Kornberg was big on enzymes (DNA polymerase) and what they helped in the experiment like catalyzing and directing the assembly of the double helix.
  • 1958: Rosalind Franklin dies of ovarian cancer when she is 37

Early 1950s:

1953:

Correct: Double Helix

  • Maurice Wilkins sees crystal spots on an x-ray of DNA, realizing that DNA is crystalline.
  • Linus Pauling believed that DNA was a triple helix. His son and James Watson realized he was wrong.
  • James Watson and Francis Crick realized that when he bases were paired it created a double helix. This caused scientists to know three letters that provided combinations to code for all the twenty amino acids called triplet code.

Wrong: Triple Helix

DNA - Cracking the Code

1960s:

1961 - ... :

By: Seun Kintunde & Stephen Nickisch

  • Sydney Brenner conducted more experiments about the messenger RNA.
  • Matthew Meselson and Frank Stahl's papers were published in an issue of Nature.
  • Francois Jacob and Jacques Monod named the messenger RNA. They created a model of mRNA that could be fumed at different speeds and result in a different speed of the protein.
  • Marshall Nirenberg thought that the three bases in DNA corresponded to a single amino acid so there were 64 possible combinations of the three bases. In nucleic acid, the first codon corresponds to an amino acid in a protein. He created a genetic code.Also, he could separate the complex from the RNA by absorption which helps make assay for other codons.

1960s:

1961:

  • There's a system called the Lac Operon which is a system of feedback and negative regulation that can control the production of proteins.

1962:

  • Watson and Crick and Wilkins win the Nobel Prize.
  • Easy codons allowed scientists to identify exact triplets that could be used to figure out the rest. They realized that a tRNA molecule that matched a mRNA codon would come together and a nucleotide would be added. The tRNA would then read the sequence and when they separate an amino acid could be identified.

1960s:

Late 1960s:

  • Walter Gilbert knew that molecules should interact with the sugar that came into the cell.
  • Benno Muller-Hill modified the bacteria, which had created a mutation that would change the way the repressor would attach to the small molecule.

1970:

  • Scientists realized that DNA is coiled around proteins and packaged as a chromatin. The uncoiling of DNA controls the production of proteins.
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