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Friedrich Meischer
Friedrich Meischer was a chemist who first discovered the substance we now call DNA. He was successfully extracted it from the cell nuclei. He determined that it was not a protein. He also discovered that it had lots of nitrogen and phosphorus. But he was never able to identify DNA's function. -
Linus Pauling
Linus Pauling greatly contributed to Watson and Crick's theory of the double helix structure of DNA. Linus Pauling studied the use of crystallography. He soon became very skilled at crystallography. Pauling was able to use it to determine the shapes of proteins. This knowledge helped a lot because then people knew they may be able to do the same thing with DNA and was later named the founder of molecular biology. -
Frederick Griffith
Fredrick Griffith uncovered an important clue to discovering the function of DNA. He had been studying pnumonia-causing bacteria in hopes of finding a cure. He was able to isolate a harmless strand(R) and a lethal one(S). He had used these strands to infect mice. He discovered that heat destroyed the lethal strands ability to infect the mice. But the hereditary information could not be destroyed so it could be put in the non lethal strand and the harmless strand became lethal to the mice. -
Oswald Avery, Maclyn McCarty and Colin McCloed
They tried to identify the substance they called the "Transforming Principle", with the process of elimination. They made an extract of cells that only contained lipids, proteins and nucleic acids. After being treated with lipid and protein killing enzymes, the cells could still transform other cells so it had to be a nucleic acid. DNA destroying enzymes took out the cells ability to transform other cells and RNA degrading enzymes didn't. That means that DNA must be the transforming principle -
Barbara McClintock
She observed different colored maize kernels. When using the maize she discovered that genetic information cannot/ will not be stationary. She traced the pigmentation in the kernels, to find the plants large chromosome. She isolated 2 genes which she called "controlling elements". She found that the control genes controlled the genes that control pigmentation. She found that the controlling elements could move along the chromosome, these changes affected neighboring genes. -
Erwin Chirgaff
Erwin Chirgaff discovered two very important rules for DNA. The first is that the amount of adenine and thymine in DNA were the same. Same with cytosine and guanine. This helped discover the base pair makeup of DNA. The second law he came up with was that the amounts of adenine, cytosine, guanine, and thymine varied from species to species. These two rules greatly helped researchers find the structure of DNA. -
Rosalind Franklin and Maurice Wilkins.
Rosalind Franklin and Maurice Wilkins used crystallography. Crystallography is used crystals to scatter molecules and get a better look at them. They were able to perfect this method. Using these skills they took a photo of DNA. With this picture, Watson and Crick were able to finally make a complete and correct model of DNA. They concluded that was shaped in a helix shape. Without their skills in crystallography, Watson and Crick would not have been able to find the structure of DNA. -
Alfred Hershey and Martha Chase
They proved that DNA satisfies the first property of hereditary material. They specialized in bacteriophage, a type of virus that infects bacteria. These particle carry hereditary information about how to make new viruses. After one cell has this material, it makes more material and it spreads. Hershey and Chase did many experiments to prove that DNA was that hereditary material. -
James Watson & Frances Crick
They determined that DNA was a double helix structure. They used Franklins and Wilikins picture to finalize their research on the DNA structure. They determined that DNA replicated itself by seperating into individual strands, becoming a new template. -
Matthew Meselson & Franklin Stahl
They experimented the fact that each daughter cell contains one daughter subunits. One subunit conserved from the parental DNA molecule. This experiment confirmed Watsons and Cricks "double helix". They also explained how DNA replicates. They mainly used Watson's and Crick's model. -
Frederick Sanger
Federick Sanger studied the composition of insulin. He used amino acids to break the insulin molecule into smaller parts to really study the makeup of the protein. As he kept studying he determined the amino acid sequence. He also identified how chains were linked together. -
Paul Berg
He conducted the "gene splicing" experiment. Berg split part of the DNA of a bacterial virus known as Lambda into a different virus. When broken, the virus were opened loops. To close the loops, Berg mixed 2 types of DNA to join the loops. His experiment resulted in the invention of rDNA (manmade DNA). -
Kary Mullis
He developed the Polymerase Chain Reaction (PCR). He found that it uses four ingredients (double-stranded DNA, 2 nucleotide primers, nucleotides, and polymerase). He said that when you heat these materials that the DNA splits. When the mixture cools the primers attach themselves to the complementary sites on the template strands. Mullis then states that the polymerase begins to copy the template by adding nucleotides. -
J. Craig Venter
He began the sequencing of the Human Genome Project. Venter relied on "shotgun sequencing" which he invented. He used this technique to decode 2,000-10,000 base pairs of an organism's genome. In 2000 Venter announced the rough draft sequence of the genome.
