-
Friedrick Meischer Continued
He studied medicine in Basel and Göttingen. After his graduation in 1868, he decided to pursue physiological chemistry due to a hearing impairment caused by a severe attack of typhoid fever. -
Friedrick Meischer
As a doctor, he had a supply of white blood cells, from the pus-filled bandages at the hospital where he worked. He added some chemicals to these cells and isolated a white precipitate he called nuclein. He assumed, correctly, that the precipitate was from the large nuclei of the white blood cells. Although not recognized at the time, he had isolated the first crude extract of DNA. He also determined that nuclein was made out of, Hydrogen, Oxygen, Nitrogen, and Phosphorus. -
Fredrick Griffith Continued
The remain of III-S were mixed with III-R. Both of the strains of bacteria were harmless to the mice separate but when they were put together they killed the mice. Griffith concluded that III-R transformed into a deadly III-S. He attended Liverpool University where he studied genetics. Before he worked for Liverpool Royal Infirmary. -
Fredrick Griffith
Griffiths experiment demonstrated experimental transformations, where a bacterium distinctly changes its form and function. In this experiment Griffith used two strains of Streptococcus pneumonia, these bacteria infect mice. He used type III-S and III-R. The S strain is surrounded by a polysaccharide capsule that protects is from the hosts immune system. This means the host will die. The R strain is not protected and is killed by the host. Bacteria from the III-S were killed by heat. Continued-> -
Oswald Avery, Maclyn McCarthy, and Colin McCleod Continued
This could produce a heritable change in organisms. He proved that DNA is the material from which genes are made. They had emigrated because Joseph, a Baptist minister, felt a spiritual calling to do God’s work in North America. The couple’s three sons were all born in Canada; Oswald was the second son. -
Oswald Avery, Maclyn McCarthy, and Colin McCleod
Their experiment pretty much purified and expanded on Griffiths idea that DNA is a substance that causes bacterial transformation. They proved that DNA (not proteins) can transform the properties of cells, clarifying the chemical nature of genes. Avery observed that proteases - enzymes that degrade proteins - did not destroy the transforming principle. They also found that the transforming principle had a high molecular weight. They has isolated DNA. -
Linus Pauling Continued
He was awarded the Nobel prize in chemistry two year on in 1954 and 1962. He is the only person to receive two unshared Nobel awards. He was poor growing up but he was a Chemist, Biochemist, and a peace activist. Linus's experiment contributed to Watson and Cricks breakthrough of the double helix. -
Linus Pauling
Founder of molecular biology due to his discovery of the spiral structure of proteins. Founder of quantum chemistry. He made it possible for geneticists to crack DNA code of organisms. He develop techniques in order to help prevent the inherence of genetic disorders. He had the idea that globular proteins are made up of polypeptide chains that are folded to make balls. He found the structure of the alpha helix. He also discovered hydrogen bonds. The amino acid and proteins form a helix . -
Erwin Chargaff
He discovered two rules that led to the double helix. His first rule was the number of guanine units is equal to the number of cytosine units. And the number of adenine units is equal the number of thymine units. His second rule is the composition of DNA varies from one species to another, in the relative amount of Adenine, Guanine, Thymine and Cytosine bases. He was professor of biochemistry at Columbia University medical school. Him and his family moved to Vienna durning the outbreak of WW1. -
Barbara McClintock
McClintock discovered genetic transposition. This is when genes change to different positions on chromosomes. This theory is also known as "jumping genes," and it explained how when genes move into a different position, the order of the bases change causing specific characteristics to be turned on or off by the genes(to be passed along or not). Fact: Barbara McClintock was the first woman to ever receive the Nobel Prize solo in 1983.
She worked on this from the 1940s into the 1950s. -
Alfred Hershey and Martha Chase Continued
Hershey and Chase studied bacteriophage, or viruses that attack bacteria. The phages they used were simple particles composed of protein and DNA, with the outer structures made of protein and the inner core consisting of DNA. Hershey and Chase prepared two different batches of phage. In each batch, the phage were produced in the presence of a specific radioactive element, which was incorporated into the macromolecules (DNA and protein) that made up the phage. -
Alfred Hershey and Martha Chase Continued 2
American bacteriologist and geneticist who won the 1969 Noble Prize in Medicine. -
Rosalind Franklin and Maurice Wilkins
Franklin and Wilkins worked to find the structure of DNA.These scientists both worked with a technique called x-ray crystallography which they used to purify crystals of DNA viewed using x-rays. They light is diffracted by a crystal making it possible to see the DNA double helix and make electron density maps of the molecules. The model they used was an x-ray picture of DNA called "Photograph 51" taken by Franklin. Fact: Wilkins is that he participated in creating the first atomic bomb (WW2). -
Alfred Hershey and Martha Chase
One was produced with a radioactive isotope of sulfur. The other sample was produced with radioactive phosphorus. Each sample was used to infect a different bacteria. It was then put in a blender to remove remaining phage parts from the outside of the bacteria cells. They measured the radioactivity in the pellet which was phosphorus. Almost all of the sulfur was in the supernatant. They concluded that DNA (not protein) was injected into host cells and made up the genetic material. -
James Watson and Frances Crick
Watson and Crick worked to create the first model of DNA. They failed their first attempt, but when they tried again, they were able to create the DNA double helix with the help of R Franklin's Photo 51. The model consisted of a polymer with 2 sugar-phosphate backbones and pairs of bases connecting them like a ladder. They showed that the sequence of the bases determines the DNA code. Fact: Crick announced their new discovery by going to a pub and saying "We have found the secret of life!" -
Matthew Meselson and Franklin Stahl
Meselson and Stahl worked to prove that when a DNA molecule duplicates, each daughter molecule contains one new daughter subunit and 1 subunit converted from the parent. Their experiment gave the base for how hereditary traits and diseases are transmitted during replication. Fact: They used an ultracentrifuge to separate the parent and daughter cells because of their different densities. The ultracentrifuge spun so fast that the separation happened at a force 144,000 times the force of gravity. -
Paul Berg
Berg is the first person to create Recombinant DNA which combines DNA from two different sources to create something new. The method he used is called gene splicing where he took one gene from a virus and put it into the DNA of a different virus. Fact: Berg convinced the whole world to stop working with Recombinant DNA, until they understood the dangers of it and create safety procedures. -
Frederick Sanger
Sanger was the first scientist to create a method of Rapid DNA Sequencing. DNA sequencing shows the order of bases in strands of DNA. This helped by enabling other scientists study and decipher the functions of different DNA sequences quicker. He inserted enzymes into DNA being synthesized, and used radioactive markers to be able to identify individual bases, allowing him to map the order of the bases to describe their patterns. Fact: He's one of three to ever receive the Nobel Prize twice. -
Kary Mullis
Mullis created the Polymerase Chain Reaction which multiplies one strand of DNA millions of times in a few hours. He came up with the idea of using 2 opposite primers on each strand of DNA, then he used multiple processes to exponentially copy the DNA between the 2 primers. PCR makes an almost unlimited supply of DNA for scientists to use. Fact: A whole new scientific field was created using this method. Paleobiology is using DNA from fossils and PCR to copy that DNA and study it multiple times. -
J. Craig Venter
Venter developed the EST method of finding genes, and promoted it as cheaper and faster than the Human Genome Project that was just getting started. Project administrators disagreed, but in the meantime, the NIH decided to patent Venter's gene fragments. The Patent Office eventually rejected the patents, but the applications sparked an international controversy over patenting genes whose functions were still unknown. He is 72 years old and is a CEO at J. Craig Venter Institute
