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DNA Discovery Timeline
Transcript of DNA Discovery Timeline
- Looked at the segregation of parental genes and their appearance in the offspring.
- Mendel's Laws of Heredity are:
1)The Law of Segregation
2)The Law of Independent Assortment
3) The Law of Dominance - Miescher isolated the nuclei from white blood cells and ended up with a substance that contained nitrogen & phosphorus.
- He named it "nuclein" but later the name was changed to "nucleic acid".
-Miescher had discovered DNA. Many researchers worked to determine whether or not DNA or proteins were the agents of heredity and others continued on with Miescher's work. 1 1 1 2 3 3 1866 1869 1928 - Griffith experimented with mice with the use of a bacterium that was causes pneumonia.
- In his experiment, he used deadly and non-deadly pneumonia. The mice that were injected with non-deadly pneumonia lived.
- The killed deadly bacteria passed on characteristics to the non-deadly making it a deadly bacteria. He claimed this to be in the inheritance molecule and called this a transformation. 4 5 6 Some bacteria was heated
and some was not. Walther Flemming - Flemming developed a staining technique to identify chromosomes and the structure of the cell nucleus.
- He also discovered mitosis and took it really far. He is said to be the first to use this term for cell division. Flemming also came up with the word chromatin which has its roots in a Greek word.
- Walther Flemming is known as the father of cytogenetics. 7 7 7 1879 Phoebus Levene - Levene seperated two types of nucleic acid of which one was named "ribose nucliec acid". This was based on the fact that ribose was present (5-C sugar).
- The other nucleic acide was same structurally but had one less oxygen atom. Levene named this "deoxyribose nucleic acid".
- Also brought forth the fact that RNA & DNA are made up of individual units known as nucleotides. early 1900s changed to :
ribonucleic acid (RNA) changed to :
(DNA) composed of 4 N-containing bases,
sugar molecule & P group 1 1 1 Avery, MacLeod & McCarty - These three scientists published a study that supported the hypothesis that DNA was the hereditary material.
- After performing an experiment, it was shown that DNA caused transformations.
- These scientists aslso developed methods to isolate and characterize (chemically) the transforming principle. Erwin Chargaff 1944 1944 - Chargaff was inspired by the discovery made by Avery and his colleagues so he started his own research program to study the chemistry of nucleic acids.
- He determined how genetic information was kept in DNA.
- Chargaff came down to two conclusions which were:
1) There is a variation in composition of nucleotides among species
2) All DNA maintains certain properties although compositions vary. It was found that the amount of adenine in any sample is equivalent to the amount of thymine. The same applies to cytosine and guanine, they are both equivalent to one another. Hershey & Chase - Hershey and Chase designed the most famous experiments in which protein was ruled out in favour of DNA as being the hereditary material.
- Their experiments settled the matter of which molecule is the genetic material. The results provided evidence that viral DNA was transferred to the bacterial cells and held the genetic info needed for viruses to reproduce.
- The experiment aimed to determine which part of the virus enters calls and directs the production of more viruses. 1952 1 1 1 A=T
C=G - known as Chargaff's rule *All had to do with genes,offspring, dominant,recessive,etc 1 1 1 1 1 1 Rosalind Franklin - Rosalind worked on the X-Ray diffraction of DNA which led to the discovery of the double helix.
- She discovered the beta form of the helix and the location of the phosphate groups on the structure.
- Her work was not accounted for in that time but her discoveries play a huge role on how we see DNA today. 1952 5 5 5 Watson & Crick - These two scientists were trying to make a model of DNA and the x-ray diffraction images that belonged to Rosalind Franklin came in really handy because it was highly accurate.
- They published their discovery and their model represented how DNA is replicated and how hereditary information is coded on it.
- In 1962, Watson, Crick & Wilkins won the Nobel Prize in Medicine. Franklin could not receive this prize because she had passed away. 6 8 8 Matthew Meselson & Franklin Stahl - The two scientists wanted to find a way to prove or disapprove Watson and Crick's model for semi-conservative replication.
- They invented a new technique that was called density gradient centrifugation which uses this force to separate molecules based on their densities.
- Their paper was published in 1958. -proved Watson & Crick's
model of semi-conservative
replication 1957 1953 3 3 3 George Beadle & Edward Tatum - Through there experiments they have shown how genes direct the synthesis of enzymes that control metabolic processes.
- Conducted an experiment with a mold called, Neurospora, and it went through many processes. These processes included recombination, mutant genes, and replication.
- They were both award the Nobel Prize in Physiology/Medicine in 1958. 1941 9 9 9 Arthur Kornberg - Arthur isolated DNA polymerase I to show that DNA could be made in a test tube.
- Kornberg was award the Nobel Prize in Physiology and Medicine along with another scientist.
- Arthur's son isolated DNA polymerase III. 3 3 3 1958 Frederick Sanger - Sanger developed methods for studying proteins and many other enzymes.
- Began studying RNA and DNA and developed methods to determine the sequences in RNA. He also found the method in determining sequences in DNA.
- This method was used to determine the DNA sequence of nucleotides in the human mitochondrial DNA. This method was later revised and used in human genome. 1958 or 1960 10 10 10 Sydney Brenner - Brenner worked on the genetic code and the role of RNA in information transfer.
- He sent a paper to the RNA tie club stating that 3 nucleotides code for one amino acid.
- By connecting genetic mutations with amino acid sequences, these scientists were able to prove the relation between the genetic message and the protein product. 1956 3 3 3 Barbara McClintock - Barbara McClintonk discovered that genes have the ability to change position on the chromosome.
- Her theories of genetic control were similar to the theories of 2 other French beauties.
- Barbara also received the Nobel prize for her discovery of mobile genetic genes. 1931 11 11 11 Mullis, Wilmut and Campbell - Mullis invented the polymerase chain reaction, which is a method of cloning DNA fragments.
- Ian Wilmut was the first embryologist that cloned a sheep(mammal) named Dolly.
- Keith Campbell assisted him in his later experiments. Their experiments led them to believe that any cell could be cloned. 1983, 1997 12 13 13 Allan Maxam & Walter Gilbert 1976 - They developed a DNA sequencing method that was based on chemical modifications.
- This method originated from the study of DNA- protein interactions.
- Their method was more popular because purified DNA could be used directly. Okazaki Smith & Hutchison Cohen and Boyer Ruddle, Constantini & Lacy Archibald Garrod -Discovered the way the lagging strand of DNA is replicated through fragments.
-This experiment was conducted using E.Coli.
-Okazaki and his wife concluded that RNA primer is removed by the use of DNA polymerase I and bases are joined together by DNA ligase (enzyme). -Hamilton Smith isolated the first restriction enzyme.
-This enzyme (HindII) could cut DNA molecules that are in specific recognition sites. -Herb Boyer and Paul Berg produced the very first DNA recombinant molecule.
-Stanley Cohen experimented and came to the conclusion that these recombinant DNA molecules could be maintained and replicated.
-They were experimented with the enzyme, E.Coli. -Ruddle and a number of other scientists injected cloned DNA into the nucleus of a fertilized egg to create the first transgenic mice.
-These 3 scientists performed a lab in which they injected DNA into a single-celled mouse embryo.
-This showed the transfer of genetic material into the later generations. -Garrod connected Mendel’s Law of Inheritance to a human disorder.
-He also came up with the idea that disease come from a metabolic route that leads to molecular basis of inheritance.
-He published books on both of his findings. 1902 16 16 16 1966 15 15 15 2 2 1970 1972-1973 2 2 2 12 14 14 1981 The End Gregor Mendel DNA Molecule
Structure Process of the experiment done by Griffith along with its conclusion. Hershey & Chase Ian Wilmut along side Dolly, the sheep he had cloned. Replication model A & C were other experimented models but model B, the Semi-conservative model was considered true. Example of where okazaki fragments would lie on a DNA replication fork. By: Jasdeep Lally